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Distributed Monitoring with Master, Satellites, and Clients

This chapter will guide you through the setup of a distributed monitoring environment, including high-availability clustering and setup details for the Icinga 2 client.

Roles: Master, Satellites, and Clients

Icinga 2 nodes can be given names for easier understanding:

A master node which is on top of the hierarchy.
A satellite node which is a child of a satellite or master node.
A client node which works as an agent connected to master and/or satellite nodes.

Rephrasing this picture into more details:

A master node has no parent node.
- A masternode is where you usually install Icinga Web 2.
- A master node can combine executed checks from child nodes into backends and notifications.
A satellite node has a parent and a child node.
- A satellite node may execute checks on its own or delegate check execution to child nodes.
- A satellite node can receive configuration for hosts/services, etc. from the parent node.
- A satellite node continues to run even if the master node is temporarily unavailable.
A client node only has a parent node.
- A client node will either run its own configured checks or receive command execution events from the parent node.

The following sections will refer to these roles and explain the differences and the possibilities this kind of setup offers.

Tip: If you just want to install a single master node that monitors several hosts (i.e. Icinga 2 clients), continue reading -- we'll start with simple examples. In case you are planning a huge cluster setup with multiple levels and lots of clients, read on -- we'll deal with these cases later on.

The installation on each system is the same: You need to install the Icinga 2 package and the required plugins.

The required configuration steps are mostly happening on the command line. You can also automate the setup.

The first thing you need learn about a distributed setup is the hierarchy of the single components.

Zones

The Icinga 2 hierarchy consists of so-called zone objects. Zones depend on a parent-child relationship in order to trust each other.

Have a look at this example for the satellite zones which have the master zone as a parent zone:

object Zone "master" {
   //...
}

object Zone "satellite region 1" {
  parent = "master"
  //...
}

object Zone "satellite region 2" {
  parent = "master"
  //...
}

There are certain limitations for child zones, e.g. their members are not allowed to send configuration commands to the parent zone members. Vice versa, the trust hierarchy allows for example the master zone to send configuration files to the satellite zone. Read more about this in the security section.

client nodes also have their own unique zone. By convention you can use the FQDN for the zone name.

Endpoints

Nodes which are a member of a zone are so-called Endpoint objects.

Here is an example configuration for two endpoints in different zones:

object Endpoint "icinga2-master1.localdomain" {
  host = "192.168.56.101"
}

object Endpoint "icinga2-satellite1.localdomain" {
  host = "192.168.56.105"
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ]
}

object Zone "satellite" {
  endpoints = [ "icinga2-satellite1.localdomain" ]
  parent = "master"
}

All endpoints in the same zone work as high-availability setup. For example, if you have two nodes in the master zone, they will load-balance the check execution.

Endpoint objects are important for specifying the connection information, e.g. if the master should actively try to connect to a client.

The zone membership is defined inside the Zone object definition using the endpoints attribute with an array of Endpoint names.

If you want to check the availability (e.g. ping checks) of the node you still need a Host object.

ApiListener

In case you are using the CLI commands later, you don't have to write this configuration from scratch in a text editor. The ApiListener object is used to load the SSL certificates and specify restrictions, e.g. for accepting configuration commands.

It is also used for the Icinga 2 REST API which shares the same host and port with the Icinga 2 Cluster protocol.

The object configuration is stored in the /etc/icinga2/features-enabled/api.conf file. Depending on the configuration mode the attributes accept_commands and accept_config can be configured here.

In order to use the api feature you need to enable it and restart Icinga 2.

icinga2 feature enable api

Conventions

By convention all nodes should be configured using their FQDN.

Furthermore, you must ensure that the following names are exactly the same in all configuration files:

Host certificate common name (CN).
Endpoint configuration object for the host.
NodeName constant for the local host.

Setting this up on the command line will help you to minimize the effort. Just keep in mind that you need to use the FQDN for endpoints and for common names when asked.

Security

While there are certain mechanisms to ensure a secure communication between all nodes (firewalls, policies, software hardening, etc.), Icinga 2 also provides additional security:

SSL certificates are mandatory for communication between nodes. The CLI commands help you create those certs automatically.
Child zones only receive updates (check results, commands, etc.) for their configured objects.
Zones cannot interfere with other zones and influence each other. Each checkabke host or service object is assigned to one zone only.
All nodes in a zone trust each other.
Config sync and remote command endpoint execution is disabled by default.

The underlying protocol is using JSON-RPC events sent over TLS secured connections. In case you are interested in specific details, please check the source code.

Master Setup

This section explains how to install a central single master node using the node wizard command. If you prefer to do an automated installation, please refer to the automated setup section.

Install the Icinga 2 package and setup the required plugins if you haven't done so already.

Note: Windows is not supported for a master node setup.

The next step is to run the node wizard CLI command. Prior to that ensure to collect the required information:

Parameter	Description
Common name (CN)	Required. By convention this should be the host's FQDN. Defaults to the FQDN.
API bind host	Optional. Allows to specify the address the ApiListener is bound to. For advanced usage only.
API bind port	Optional. Allows to specify the port the ApiListener is bound to. For advanced usage only (requires changing the default port 5665 everywhere).

The setup wizard will ensure that the following steps are taken:

Enable the api feature.
Generate a new certificate authority (CA) in /var/lib/icinga2/ca if it doesn't exist.
Create a certificate signing request (CSR) for the local node.
Sign the CSR with the local CA and copy all files to the /etc/icinga2/pki directory.
Update the zones.conf file with the new zone hierarchy.
Update /etc/icinga2/features-enabled/api.conf and constants.conf.

Here is an example of a master setup for the icinga2-master1.localdomain node on CentOS 7:

[root@icinga2-master1.localdomain /]# icinga2 node wizard
Welcome to the Icinga 2 Setup Wizard!

We'll guide you through all required configuration details.

Please specify if this is a satellite setup ('n' installs a master setup) [Y/n]: n
Starting the Master setup routine...
Please specify the common name (CN) [icinga2-master1.localdomain]: icinga2-master1.localdomain
Checking for existing certificates for common name 'icinga2-master1.localdomain'...
Certificates not yet generated. Running 'api setup' now.
information/cli: Generating new CA.
information/base: Writing private key to '/var/lib/icinga2/ca/ca.key'.
information/base: Writing X509 certificate to '/var/lib/icinga2/ca/ca.crt'.
information/cli: Generating new CSR in '/etc/icinga2/pki/icinga2-master1.localdomain.csr'.
information/base: Writing private key to '/etc/icinga2/pki/icinga2-master1.localdomain.key'.
information/base: Writing certificate signing request to '/etc/icinga2/pki/icinga2-master1.localdomain.csr'.
information/cli: Signing CSR with CA and writing certificate to '/etc/icinga2/pki/icinga2-master1.localdomain.crt'.
information/cli: Copying CA certificate to '/etc/icinga2/pki/ca.crt'.
Generating master configuration for Icinga 2.
information/cli: Adding new ApiUser 'root' in '/etc/icinga2/conf.d/api-users.conf'.
information/cli: Enabling the 'api' feature.
Enabling feature api. Make sure to restart Icinga 2 for these changes to take effect.
information/cli: Dumping config items to file '/etc/icinga2/zones.conf'.
information/cli: Created backup file '/etc/icinga2/zones.conf.orig'.
Please specify the API bind host/port (optional):
Bind Host []:
Bind Port []:
information/cli: Created backup file '/etc/icinga2/features-available/api.conf.orig'.
information/cli: Updating constants.conf.
information/cli: Created backup file '/etc/icinga2/constants.conf.orig'.
information/cli: Updating constants file '/etc/icinga2/constants.conf'.
information/cli: Updating constants file '/etc/icinga2/constants.conf'.
information/cli: Updating constants file '/etc/icinga2/constants.conf'.
Done.

Now restart your Icinga 2 daemon to finish the installation!

[root@icinga2-master1.localdomain /]# systemctl restart icinga2

As you can see, the CA public and private key are stored in the /var/lib/icinga2/ca directory. Keep this path secure and include it in your backups.

In case you lose the CA private key you have to generate a new CA for signing new client certificate requests. You then have to also re-create new signed certificates for all existing nodes.

Once the master setup is complete, you can also use this node as primary CSR auto-signing master. The following section will explain how to use the CLI commands in order to fetch their signed certificate from this master node.

Client/Satellite Setup

This section describes the setup of a satellite and/or client connected to an existing master node setup. If you haven't done so already, please run the master setup.

Icinga 2 on the master node must be running and accepting connections on port 5665.

CSR Auto-Signing

The node wizard command will set up a satellite/client using CSR auto-signing. This involves that the setup wizard sends a certificate signing request (CSR) to the master node. There is a security mechanism in place which requires the client to send in a valid ticket for CSR auto-signing.

This ticket must be generated beforehand. The ticket_salt attribute for the ApiListener must be configured in order to make this work.

There are two possible ways to retrieve the ticket:

CLI command executed on the master node.
REST API request against the master node.

Required information:

Parameter	Description
Common name (CN)	Required. The common name for the satellite/client. By convention this should be the FQDN.

The following example shows how to generate a ticket on the master node icinga2-master1.localdomain for the client icinga2-client1.localdomain:

[root@icinga2-master1.localdomain /]# icinga2 pki ticket --cn icinga2-client1.localdomain

Querying the Icinga 2 API on the master requires an ApiUser object with at least the actions/generate-ticket.

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/conf.d/api-users.conf

object ApiUser "client-pki-ticket" {
  password = "bea11beb7b810ea9ce6ea" //change this
  permissions = [ "actions/generate-ticket" ]
}

[root@icinga2-master1.localdomain /]# systemctl restart icinga2

Retrieve the ticket on the master node icinga2-master1.localdomain with curl, for example:

 [root@icinga2-master1.localdomain /]# curl -k -s -u client-pki-ticket:bea11beb7b810ea9ce6ea -H 'Accept: application/json' \
 -X POST 'https://icinga2-master1.localdomain:5665/v1/actions/generate-ticket' -d '{ "cn": "icinga2-client1.localdomain" }'

Store that ticket number for the satellite/client setup below.

Note: Never expose the ticket salt and/or ApiUser credentials to your client nodes. Example: Retrieve the ticket on the Puppet master node and send the compiled catalog to the authorized Puppet agent node which will invoke the automated setup steps.

Client/Satellite Linux Setup

Please ensure that you've run all the steps mentioned in the client/satellite section.

Install the Icinga 2 package and setup the required plugins if you haven't done so already.

The next step is to run the node wizard CLI command. Prior to that ensure to collect the required information:

Parameter	Description
Common name (CN)	Required. By convention this should be the host's FQDN. Defaults to the FQDN.
Master common name	Required. Use the common name you've specified for your master node before.
Establish connection to the master	Optional. Whether the client should attempt to connect the to master or not. Defaults to `y`.
Master endpoint host	Required if the the client needs to connect to the master. The master's IP address or FQDN. This information is included in the `Endpoint` object configuration in the `zones.conf` file.
Master endpoint port	Optional if the the client needs to connect to the master. The master's listening port. This information is included in the `Endpoint` object configuration.
Add more master endpoints	Optional. If you have multiple master nodes configured, add them here.
Master connection for CSR auto-signing	Required. The master node's IP address or FQDN and port where the client should request a certificate from. Defaults to the master endpoint host.
Certificate information	Required. Verify that the connecting host really is the requested master node.
Request ticket	Required. Paste the previously generated ticket number.
API bind host	Optional. Allows to specify the address the ApiListener is bound to. For advanced usage only.
API bind port	Optional. Allows to specify the port the ApiListener is bound to. For advanced usage only (requires changing the default port 5665 everywhere).
Accept config	Optional. Whether this node accepts configuration sync from the master node (required for config sync mode). For security reasons this defaults to `n`.
Accept commands	Optional. Whether this node accepts command execution messages from the master node (required for command endpoint mode). For security reasons this defaults to `n`.

The setup wizard will ensure that the following steps are taken:

Enable the api feature.
Create a certificate signing request (CSR) for the local node.
Request a signed certificate with the provided ticket number on the master node.
Allow to verify the master's certificate.
Store the signed client certificate and ca.crt in /etc/icinga2/pki.
Update the zones.conf file with the new zone hierarchy.
Update /etc/icinga2/features-enabled/api.conf (accept_config, accept_commands) and constants.conf.

In this example we're generating a ticket on the master node icinga2-master1.localdomain for the client icinga2-client1.localdomain:

[root@icinga2-master1.localdomain /]# icinga2 pki ticket --cn icinga2-client1.localdomain
4f75d2ecd253575fe9180938ebff7cbca262f96e

The following example shows a client setup for the icinga2-client1.localdomain node on CentOS 7. This client is configured to accept configuration and commands from the master:

[root@icinga2-client1.localdomain /]# icinga2 node wizard
Welcome to the Icinga 2 Setup Wizard!

We'll guide you through all required configuration details.

Please specify if this is a satellite setup ('n' installs a master setup) [Y/n]:
Starting the Node setup routine...
Please specify the common name (CN) [icinga2-client1.localdomain]: icinga2-client1.localdomain
Please specify the master endpoint(s) this node should connect to:
Master Common Name (CN from your master setup): icinga2-master1.localdomain
Do you want to establish a connection to the master from this node? [Y/n]:
Please fill out the master connection information:
Master endpoint host (Your master's IP address or FQDN): 192.168.56.101
Master endpoint port [5665]:
Add more master endpoints? [y/N]:
Please specify the master connection for CSR auto-signing (defaults to master endpoint host):
Host [192.168.56.101]: 192.168.2.101
Port [5665]:
information/base: Writing private key to '/etc/icinga2/pki/icinga2-client1.localdomain.key'.
information/base: Writing X509 certificate to '/etc/icinga2/pki/icinga2-client1.localdomain.crt'.
information/cli: Fetching public certificate from master (192.168.56.101, 5665):

Certificate information:

 Subject:     CN = icinga2-master1.localdomain
 Issuer:      CN = Icinga CA
 Valid From:  Feb 23 14:45:32 2016 GMT
 Valid Until: Feb 19 14:45:32 2031 GMT
 Fingerprint: AC 99 8B 2B 3D B0 01 00 E5 21 FA 05 2E EC D5 A9 EF 9E AA E3

Is this information correct? [y/N]: y
information/cli: Received trusted master certificate.

Please specify the request ticket generated on your Icinga 2 master.
 (Hint: # icinga2 pki ticket --cn 'icinga2-client1.localdomain'): 4f75d2ecd253575fe9180938ebff7cbca262f96e
information/cli: Requesting certificate with ticket '4f75d2ecd253575fe9180938ebff7cbca262f96e'.

information/cli: Created backup file '/etc/icinga2/pki/icinga2-client1.localdomain.crt.orig'.
information/cli: Writing signed certificate to file '/etc/icinga2/pki/icinga2-client1.localdomain.crt'.
information/cli: Writing CA certificate to file '/etc/icinga2/pki/ca.crt'.
Please specify the API bind host/port (optional):
Bind Host []:
Bind Port []:
Accept config from master? [y/N]: y
Accept commands from master? [y/N]: y
information/cli: Disabling the Notification feature.
Disabling feature notification. Make sure to restart Icinga 2 for these changes to take effect.
information/cli: Enabling the Apilistener feature.
information/cli: Generating local zones.conf.
information/cli: Dumping config items to file '/etc/icinga2/zones.conf'.
information/cli: Updating constants.conf.
information/cli: Updating constants file '/etc/icinga2/constants.conf'.
information/cli: Updating constants file '/etc/icinga2/constants.conf'.
Done.

Now restart your Icinga 2 daemon to finish the installation!

[root@icinga2-master1.localdomain /]# systemctl restart icinga2

As you can see, the certificate files are stored in the /etc/icinga2/pki directory.

Now that you've successfully installed a satellite/client, please proceed to the configuration modes.

Client/Satellite Windows Setup

Download the MSI-Installer package from http://packages.icinga.org/windows/.

Requirements:

Windows Vista/Server 2008 or higher
Microsoft .NET Framework 2.0

The installer package includes the NSClient++ so that Icinga 2 can use its built-in plugins. You can find more details in this chapter. The Windows package also installs native monitoring plugin binaries to get you started more easily.

The graphical installer will offer to run the Icinga 2 setup wizard after the installation. You can also manually run the Icinga 2 setup wizard from the Start menu.

On a fresh installation the setup wizard will guide you through the initial configuration and offer to use CSR auto-signing for generating the SSL certificate. You'll need the following configuration details:

Parameter	Description
Common name (CN)	Required. By convention this should be the host's FQDN. Defaults to the FQDN.
Request ticket	Required. Paste the previously generated ticket number.

Fill in the required information and click Add to add a new master connection.

Add the following details:

Parameter	Description
Instance name	Required. The master endpoint name.
Master endpoint host	Required if the the client needs to connect to the master. The master's IP address or FQDN. This information is included in the `Endpoint` object configuration in the `zones.conf` file.
Master endpoint port	Optional if the the client needs to connect to the master. The master's listening port. This information is included in the `Endpoint` object configuration.

Optionally, you can enable the following settings:

Parameter	Description
Accept config	Optional. Whether this node accepts configuration sync from the master node (required for config sync mode). For security reasons this is disabled by default.
Accept commands	Optional. Whether this node accepts command execution messages from the master node (required for command endpoint mode). For security reasons this is disabled by default.
Install NSClient++	Optional. The Windows installer bundles the NSClient++ installer for additional plugin checks.

The next step allows you to verify the CA presented by the master.

If you have chosen to install/update the NSClient++ package, the Icinga 2 setup wizard will ask you to do so.

Finish the setup wizard.

After the installation and configuration Icinga 2 is automatically started as a Windows service.

The Icinga 2 configuration is stored inside the C:\ProgramData\icinga2 directory. If you click Examine Config in the setup wizard, it will open a new Explorer window.

The configuration files can be modified with your favorite editor.

To validate the configuration on Windows open a terminal and enter the following command:

C:> icinga2.exe daemon -C

Note: You have to run this command in a shell with administrator privileges.

In case you want to restart the Icinga 2 service, run services.msc and restart the icinga2 service. Alternatively, you can use the net {start,stop} CLI commands.

Now that you've successfully installed a satellite/client, please proceed to the configuration modes.

Configuration Modes

There are different ways to ensure that the Icinga 2 cluster nodes execute checks, send notifications, etc.

Two different modes are available for synchronizing the host/service object's configuration between nodes and for executing checks:

Top down: This mode sends the configuration and commands from the master to the child zones.
Bottom up: This mode leaves the configuration on the child nodes and requires an import on the parent nodes.

The next sections describe the differences and how to set up the two modes. Read them carefully before you decide on one of the two options -- do not mix them, as this will make things unnecessarily complicated.

Note: Check results are always sent from the child nodes to the parent nodes. This happens automatically and is ensured by the cluster protocol.

Top Down

According to feedback that we've received from the community, this is the most commonly used mode.

There are two different behaviors with check execution:

Send a command execution event remotely: The scheduler still runs on the parent node.
Sync the host/service objects directly to the child node: Checks are executed locally.

Again, technically it does not matter whether this is a client or a satellite which is receiving configuration or command execution events.

Top Down Command Endpoint

This mode will force the Icinga 2 node to execute commands remotely on a specified endpoint. The host/service object configuration is located on the master/satellite and the client only needs the CheckCommand object definitions being used there.

Advantages:

No local checks need to be defined on the child node (client).
Light-weight remote check execution (asynchronous events).
No replay log is necessary for the child node.
Pin checks to specific endpoints (if the child zone consists of 2 endpoints).

Disadvantages:

If the child node is not connected, no more checks are executed.
Requires additional configuration attribute specified in host/service objects.
Requires local CheckCommand object configuration. Best practice is to use a global config zone.

To make sure that all nodes involved will accept configuration and/or commands, you need to configure the Zone and Endpoint hierarchy on all nodes.

icinga2-master1.localdomain is the configuration master in this scenario.
icinga2-client2.localdomain acts as client which receives command execution messages via command endpoint from the master. In addition, it receives the global check command configuration from the master.

Include the endpoint and zone configuration on both nodes in the file /etc/icinga2/zones.conf.

The endpoint configuration could look like this, for example:

object Endpoint "icinga2-master1.localdomain" {
  host = "192.168.56.101"
}

object Endpoint "icinga2-client2.localdomain" {
  host = "192.168.56.112"
}

Next, you need to define two zones. There is no naming convention, best practice is to either use master, satellite/client-fqdn or to choose region names for example Europe, USA and Asia, though.

Note: Each client requires its own zone and endpoint configuration. Best practice is to use the client's FQDN for all object names.

The master zone is a parent of the icinga2-client2.localdomain zone:

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ] //array with endpoint names
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "master" //establish zone hierarchy
}

In addition, add a global zone for syncing check commands later:

object Zone "global-templates" {
  global = true
}

Edit the api feature on the client icinga2-client2.localdomain in the /etc/icinga2/features-enabled/api.conf file and make sure to set accept_commands and accept_config to true:

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/features-enabled/api.conf

object ApiListener "api" {
   //...
   accept_commands = true
   accept_config = true
}

Now it is time to validate the configuration and to restart the Icinga 2 daemon on both nodes.

Example on CentOS 7:

[root@icinga2-client2.localdomain /]# icinga2 daemon -C
[root@icinga2-client2.localdomain /]# systemctl restart icinga2

[root@icinga2-master1.localdomain /]# icinga2 daemon -C
[root@icinga2-master1.localdomain /]# systemctl restart icinga2

Once the clients have successfully connected, you are ready for the next step: execute a remote check on the client using the command endpoint.

Include the host and service object configuration in the master zone -- this will help adding a secondary master for high-availability later.

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/master

Add the host and service objects you want to monitor. There is no limitation for files and directories -- best practice is to sort things by type.

By convention a master/satellite/client host object should use the same name as the endpoint object. You can also add multiple hosts which execute checks against remote services/clients.

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/master
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim hosts.conf

object Host "icinga2-client2.localdomain" {
  check_command = "hostalive" //check is executed on the master
  address = "192.168.56.112"

  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

Given that you are monitoring a Linux client, we'll add a remote disk check.

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim services.conf

apply Service "disk" {
  check_command = "disk"

  //specify where the check is executed
  command_endpoint = host.vars.client_endpoint

  assign where host.vars.client_endpoint
}

If you have your own custom CheckCommand definition, add it to the global zone:

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/global-templates
[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.d/global-templates/commands.conf

object CheckCommand "my-cmd" {
  //...
}

Save the changes and validate the configuration on the master node:

[root@icinga2-master1.localdomain /]# icinga2 daemon -C

Restart the Icinga 2 daemon (example for CentOS 7):

[root@icinga2-master1.localdomain /]# systemctl restart icinga2

The following steps will happen:

Icinga 2 validates the configuration on icinga2-master1.localdomain and restarts.
The icinga2-master1.localdomain node schedules and executes the checks.
The icinga2-client2.localdomain node receives the execute command event with additional command parameters.
The icinga2-client2.localdomain node maps the command parameters to the local check command, executes the check locally, and sends back the check result message.

As you can see, no interaction from your side is required on the client itself, and it's not necessary to reload the Icinga 2 service on the client.

You have learned the basics about command endpoint checks. Proceed with the scenarios section where you can find detailed information on extending the setup.

Top Down Config Sync

This mode syncs the object configuration files within specified zones. It comes in handy if you want to configure everything on the master node and sync the satellite checks (disk, memory, etc.). The satellites run their own local scheduler and will send the check result messages back to the master.

Advantages:

Sync the configuration files from the parent zone to the child zones.
No manual restart is required on the child nodes, as syncing, validation, and restarts happen automatically.
Execute checks directly on the child node's scheduler.
Replay log if the connection drops (important for keeping the check history in sync, e.g. for SLA reports).
Use a global zone for syncing templates, groups, etc.

Disadvantages:

Requires a config directory on the master node with the zone name underneath /etc/icinga2/zones.d.
Additional zone and endpoint configuration needed.
Replay log is replicated on reconnect after connection loss. This might increase the data transfer and create an overload on the connection.

To make sure that all involved nodes accept configuration and/or commands, you need to configure the Zone and Endpoint hierarchy on all nodes.

icinga2-master1.localdomain is the configuration master in this scenario.
icinga2-client1.localdomain acts as client which receives configuration from the master.

Include the endpoint and zone configuration on both nodes in the file /etc/icinga2/zones.conf.

The endpoint configuration could look like this:

object Endpoint "icinga2-master1.localdomain" {
  host = "192.168.56.101"
}

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.56.111"
}

Note: Each client requires its own zone and endpoint configuration. Best practice is to use the client's FQDN for all object names.

The master zone is a parent of the icinga2-client1.localdomain zone:

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ] //array with endpoint names
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "master" //establish zone hierarchy
}

Edit the api feature on the client icinga2-client1.localdomain in the /etc/icinga2/features-enabled/api.conf file and set accept_config to true.

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/features-enabled/api.conf

object ApiListener "api" {
   //...
   accept_config = true
}

Now it is time to validate the configuration and to restart the Icinga 2 daemon on both nodes.

Example on CentOS 7:

[root@icinga2-client1.localdomain /]# icinga2 daemon -C
[root@icinga2-client1.localdomain /]# systemctl restart icinga2

[root@icinga2-master1.localdomain /]# icinga2 daemon -C
[root@icinga2-master1.localdomain /]# systemctl restart icinga2

Tip: Best practice is to use a global zone for common configuration items (check commands, templates, groups, etc.).

Once the clients have connected successfully, it's time for the next step: execute a local check on the client using the configuration sync.

Navigate to /etc/icinga2/zones.d on your master node icinga2-master1.localdomain and create a new directory with the same name as your satellite/client zone name:

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/icinga2-client1.localdomain

Add the host and service objects you want to monitor. There is no limitation for files and directories -- best practice is to sort things by type.

By convention a master/satellite/client host object should use the same name as the endpoint object. You can also add multiple hosts which execute checks against remote services/clients.

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/icinga2-client1.localdomain
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/icinga2-client1.localdomain]# vim hosts.conf

object Host "icinga2-client1.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.111"
  zone = "master" //optional trick: sync the required host object to the client, but enforce the "master" zone to execute the check
}

Given that you are monitoring a Linux client we'll just add a local disk check.

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/icinga2-client1.localdomain]# vim services.conf

object Service "disk" {
  host_name = "icinga2-client1.localdomain"

  check_command = "disk"
}

Save the changes and validate the configuration on the master node:

[root@icinga2-master1.localdomain /]# icinga2 daemon -C

Restart the Icinga 2 daemon (example for CentOS 7):

[root@icinga2-master1.localdomain /]# systemctl restart icinga2

The following steps will happen:

Icinga 2 validates the configuration on icinga2-master1.localdomain.
Icinga 2 copies the configuration into its zone config store in /var/lib/icinga2/api/zones.
The icinga2-master1.localdomain node sends a config update event to all endpoints in the same or direct child zones.
The icinga2-client1.localdomain node accepts config and populates the local zone config store with the received config files.
The icinga2-client1.localdomain node validates the configuration and automatically restarts.

Again, there is no interaction required on the client itself.

You can also use the config sync inside a high-availability zone to ensure that all config objects are synced among zone members.

Note: You can only have one so-called "config master" in a zone which stores the configuration in the zones.d directory. Multiple nodes with configuration files in the zones.d directory are not supported.

Now that you've learned the basics about the configuration sync, proceed with the scenarios section where you can find detailed information on extending the setup.

Bottom Up Import

This mode requires that you manage the configuration on the client itself. Edit the configuration files in /etc/icinga2/conf.d or any other directory included in the icinga2.conf file.

The client will send information about the configured objects to the parent zone members where they can generate configuration objects.

Advantages:

Each child node comes configured with the most common local checks in the conf.d directory.
Central repository for zones, endpoints, hosts, and services with configuration repository import.

Disadvantages:

No object attribute sync. Parent nodes cannot filter specific attributes in assign expressions.
Does not reliably work with a HA parent zone (single master preferred).
Configuration management of many client nodes is hard or impossible if you don't have access to them.

On the master node, you can list and import the configuration sent from all the clients. This example shows all client services on the master node icinga2-master1.localdomain:

[root@icinga2-master1.localdomain /]# icinga2 node list
Node 'icinga2-client1.localdomain' (last seen: Sun Aug 14 11:19:14 2016)
    * Host 'icinga2-client1.localdomain'
        * Service 'disk'
        * Service 'disk /'
        * Service 'http'
        * Service 'icinga'
        * Service 'load'
        * Service 'ping4'
        * Service 'ping6'
        * Service 'procs'
        * Service 'ssh'
        * Service 'swap'
        * Service 'users'

Node 'icinga2-client2.localdomain' (last seen: Sun Aug 14 11:19:14 2016)
    * Host 'icinga2-client2.localdomain'
        * Service 'disk'
        * Service 'disk C:'
        * Service 'icinga'
        * Service 'load'
        * Service 'ping4'
        * Service 'ping6'
        * Service 'procs'
        * Service 'swap'
        * Service 'users'

The object configuration must exist on the master node as well in order to receive check results from the clients. Therefore you need to invoke the node update-config command:

[root@icinga2-master1.localdomain /]# icinga2 node update-config
information/cli: Updating node configuration for
...

The generated configuration objects are located in /etc/icinga2/repository.d. If you have accidentally added specific hosts or services, you can safely purge them from this directory and restart Icinga 2.

The generated host object uses the cluster-zone check command as health check.

Tip: In case you want to blacklist or whitelist certain hosts and/or services on the master, use the icinga2 node {black,white}list commands.

In this example we're first putting all ping* services on all hosts on the blacklist. With the next command we allow the host probe to run the service ping4:

# icinga2 node blacklist add --zone "*" --host "*" --service "ping*"
# icinga2 node whitelist add --zone "*" --host "probe" --service "ping4"

You can list and remove existing blacklists:

# icinga2 node blacklist list
Listing all blacklist entries:
blacklist filter for Node: '*' Host: '*' Service: 'ping*'.

# icinga2 node whitelist list
Listing all whitelist entries:
whitelist filter for Node: '*' Host: 'probe' Service: 'ping4'.

There are certain limitations with this mode. Currently the repository does not sync object attributes (custom attributes, group memberships) from the client to the master.

You can manually edit the configuration in /etc/icinga2/repository.d and fix it. This will help with additional notification apply rules or group memberships required for Icinga Web 2 and addons.

Scenarios

The following examples should give you an idea on how to build your own distributed monitoring environment. We've seen them all in production environments and received feedback from our community and partner support channels:

Single master with clients.
HA master with clients as command endpoint.
Three level cluster with config HA masters, satellites receiving config sync, and clients checked using command endpoint.

Master with Clients

icinga2-master1.localdomain is the primary master node.
icinga2-client1.localdomain and icinga2-client2.localdomain are two child nodes as clients.

Setup requirements:

Set up icinga2-master1.localdomain as master.
Set up icinga2-client1.localdomain and icinga2-client2.localdomain as client.

Edit the zones.conf configuration file on the master:

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
}

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.56.111" //the master actively tries to connect to the client
}

object Endpoint "icinga2-client2.localdomain" {
  host = "192.168.56.112" //the master actively tries to connect to the client
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ]
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "master"
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

The two client nodes do not necessarily need to know about each other. The only important thing is that they know about the parent zone and their endpoint members (and optionally the global zone).

If you specify the host attribute in the icinga2-master1.localdomain endpoint object, the client will actively try to connect to the master node. Since we've specified the client endpoint's attribute on the master node already, we don't want the clients to connect to the master. Choose one connection direction.

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-client1.localdomain" {
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ]
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

[root@icinga2-client2.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-client2.localdomain" {
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain" ]
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

Now it is time to define the two client hosts and apply service checks using the command endpoint execution method on them. Note: You can also use the config sync mode here.

Create a new configuration directory on the master node:

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/master

Add the two client nodes as host objects:

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/master
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim hosts.conf

object Host "icinga2-client1.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.111"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

object Host "icinga2-client2.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.112"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

Add services using command endpoint checks:

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim services.conf

apply Service "ping4" {
  check_command = "ping4"
  //check is executed on the master node
  assign where host.address
}

apply Service "disk" {
  check_command = "disk"

  //specify where the check is executed
  command_endpoint = host.vars.client_endpoint

  assign where host.vars.client_endpoint
}

Validate the configuration and restart Icinga 2 on the master node icinga2-master1.localdomain.

Open Icinga Web 2 and check the two newly created client hosts with two new services -- one executed locally (ping4) and one using command endpoint (disk).

High-Availability Master with Clients

This scenario is similar to the one in the previous section. The only difference is that we will now set up two master nodes in a high-availablity setup. These nodes must be configured as zone and endpoints objects.

The setup uses the capabilities of the Icinga 2 cluster. All zone members replicate cluster events amongst each other. In addition to that, several Icinga 2 features can enable HA functionality.

Note: All nodes in the same zone require that you enable the same features for high-availability (HA).

Overview:

icinga2-master1.localdomain is the config master master node.
icinga2-master2.localdomain is the secondary master master node without config in zones.d.
icinga2-client1.localdomain and icinga2-client2.localdomain are two child nodes as clients.

Setup requirements:

Set up icinga2-master1.localdomain as master.
Set up icinga2-master2.localdomain as client (we will modify the generated configuration).
Set up icinga2-client1.localdomain and icinga2-client2.localdomain as clients (when asked for adding multiple masters, set to y and add the secondary master icinga2-master2.localdomain).

In case you don't want to use the CLI commands, you can also manually create and sync the required SSL certificates. We will modify and discuss all the details of the automatically generated configuration here.

Since there are now two nodes in the same zone, we must consider the high-availability features.

Checks and notifiations are balanced between the two master nodes. That's fine, but it requires check plugins and notification scripts to exist on both nodes.
The IDO feature will only be active on one node by default. Since all events are replicated between both nodes, it is easier to just have one central database.

One possibility is to use a dedicated MySQL cluster VIP (external application cluster) and leave the IDO feature with enabled HA capabilities. Alternatively, you can disable the HA feature and write to a local database on each node. Both methods require that you configure Icinga Web 2 accordingly (monitoring backend, IDO database, used transports, etc.).

The zone hierarchy could look like this. It involves putting the two master nodes icinga2-master1.localdomain and icinga2-master2.localdomain into the master zone.

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  host = "192.168.56.101"
}

object Endpoint "icinga2-master2.localdomain" {
  host = "192.168.56.102"
}

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.56.111" //the master actively tries to connect to the client
}

object Endpoint "icinga2-client2.localdomain" {
  host = "192.168.56.112" //the master actively tries to connect to the client
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "master"
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

The two client nodes do not necessarily need to know about each other. The only important thing is that they know about the parent zone and their endpoint members (and optionally about the global zone).

If you specify the host attribute in the icinga2-master1.localdomain and icinga2-master2.localdomain endpoint objects, the client will actively try to connect to the master node. Since we've specified the client endpoint's attribute on the master node already, we don't want the clients to connect to the master nodes. Choose one connection direction.

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-master2.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-client1.localdomain" {
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

[root@icinga2-client2.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-master2.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
}

object Endpoint "icinga2-client2.localdomain" {
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

Now it is time to define the two client hosts and apply service checks using the command endpoint execution method. Note: You can also use the config sync mode here.

Create a new configuration directory on the master node icinga2-master1.localdomain. Note: The secondary master node icinga2-master2.localdomain receives the configuration using the config sync mode.

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/master

Add the two client nodes as host objects:

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/master
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim hosts.conf

object Host "icinga2-client1.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.111"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

object Host "icinga2-client2.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.112"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

Add services using command endpoint checks:

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim services.conf

apply Service "ping4" {
  check_command = "ping4"
  //check is executed on the master node
  assign where host.address
}

apply Service "disk" {
  check_command = "disk"

  //specify where the check is executed
  command_endpoint = host.vars.client_endpoint

  assign where host.vars.client_endpoint
}

Validate the configuration and restart Icinga 2 on the master node icinga2-master1.localdomain.

Open Icinga Web 2 and check the two newly created client hosts with two new services -- one executed locally (ping4) and one using command endpoint (disk).

Tip: It's a good idea to add health checks to make sure that your cluster notifies you in case of failure.

Three Levels with Master, Satellites, and Clients

This scenario combines everything you've learned so far: High-availability masters, satellites receiving their config from the master zone, and clients checked via command endpoint from the satellite zones.

Tip: It can get complicated, so grab a pen and paper and bring your thoughts to life. Play around with a test setup before using it in a production environment!

Overview:

icinga2-master1.localdomain is the config master master node.
icinga2-master2.localdomain is the secondary master master node without configuration in zones.d.
icinga2-satellite1.localdomain and icinga2-satellite2.localdomain are satellite nodes in a master child zone.
icinga2-client1.localdomain and icinga2-client2.localdomain are two child nodes as clients.

Setup requirements:

Set up icinga2-master1.localdomain as master.
Set up icinga2-master2.localdomain, icinga2-satellite1.localdomain and icinga2-satellite2.localdomain as clients (we will modify the generated configuration).
Set up icinga2-client1.localdomain and icinga2-client2.localdomain as clients.

When being asked for the master endpoint providing CSR auto-signing capabilities, please add the master node which holds the CA and has the ApiListener feature configured and enabled. The parent endpoint must still remain the satellite endpoint name.

Example for icinga2-client1.localdomain:

Please specify the master endpoint(s) this node should connect to:

Master is the first satellite icinga2-satellite1.localdomain:

Master Common Name (CN from your master setup): icinga2-satellite1.localdomain
Do you want to establish a connection to the master from this node? [Y/n]: y
Please fill out the master connection information:
Master endpoint host (Your master's IP address or FQDN): 192.168.56.105
Master endpoint port [5665]:

Add the second satellite icinga2-satellite2.localdomain as master:

Add more master endpoints? [y/N]: y
Master Common Name (CN from your master setup): icinga2-satellite2.localdomain
Do you want to establish a connection to the master from this node? [Y/n]: y
Please fill out the master connection information:
Master endpoint host (Your master's IP address or FQDN): 192.168.56.106
Master endpoint port [5665]:
Add more master endpoints? [y/N]: n

Specify the master node icinga2-master2.localdomainwith the CA private key and ticket salt:

Please specify the master connection for CSR auto-signing (defaults to master endpoint host):
Host [192.168.56.106]: icinga2-master1.localdomain
Port [5665]:

In case you cannot connect to the master node from your clients, you'll manually need to generate the SSL certificates and modify the configuration accordingly.

We'll discuss the details of the required configuration below.

The zone hierarchy can look like this. We'll define only the directly connected zones here.

You can safely deploy this configuration onto all master and satellite zone members. You should keep in mind to control the endpoint connection direction using the host attribute.

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-master1.localdomain" {
  host = "192.168.56.101"
}

object Endpoint "icinga2-master2.localdomain" {
  host = "192.168.56.102"
}

object Endpoint "icinga2-satellite1.localdomain" {
  host = "192.168.56.105"
}

object Endpoint "icinga2-satellite2.localdomain" {
  host = "192.168.56.106"
}

object Zone "master" {
  endpoints = [ "icinga2-master1.localdomain", "icinga2-master2.localdomain" ]
}

object Zone "satellite" {
  endpoints = [ "icinga2-satellite1.localdomain", "icinga2-satellite2.localdomain" ]

  parent = "master"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

Note: The master nodes do not need to know about the indirectly connected clients. Since we want to use command endpoint check configuration, we must configure the client endpoint and zone objects. In order to minimize the effort, we'll sync the client zone and endpoint config to the satellites where the connection information is needed as well.

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/{master,satellite,global-templates}
[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/satellite

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/satellite]# vim icinga2-client1.localdomain.conf

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.33.111" //the satellite actively tries to connect to the client
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "satellite"
}

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/satellite]# vim icinga2-client2.localdomain.conf

object Endpoint "icinga2-client2.localdomain" {
  host = "192.168.33.112" //the satellite actively tries to connect to the client
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "satellite"
}

The two client nodes do not necessarily need to know about each other, either. The only important thing is that they know about the parent zone and their endpoint members (and optionally the global zone).

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-satellite1.localdomain" {
  //do not actively connect to the satellite by leaving out the 'host' attribute
}

object Endpoint "icinga2-satellite2.localdomain" {
  //do not actively connect to the satellite by leaving out the 'host' attribute
}

object Endpoint "icinga2-client1.localdomain" {
}

object Zone "satellite" {
  endpoints = [ "icinga2-satellite1.localdomain", "icinga2-satellite2.localdomain" ]
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]

  parent = "satellite"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

[root@icinga2-client2.localdomain /]# vim /etc/icinga2/zones.conf

object Endpoint "icinga2-satellite1.localdomain" {
  //do not actively connect to the satellite by leaving out the 'host' attribute
}

object Endpoint "icinga2-satellite2.localdomain" {
  //do not actively connect to the satellite by leaving out the 'host' attribute
}

object Endpoint "icinga2-client2.localdomain" {
}

object Zone "satellite" {
  endpoints = [ "icinga2-satellite1.localdomain", "icinga2-satellite2.localdomain" ]
}

object Zone "icinga2-client2.localdomain" {
  endpoints = [ "icinga2-client2.localdomain" ]

  parent = "satellite"
}

/* sync global commands */
object Zone "global-templates" {
  global = true
}

Now it is time to define the two client hosts on the master, sync them to the satellites and apply service checks using the command endpoint execution method to them. Add the two client nodes as host objects to the satellite zone.

We've already created the directories in zones.d, the files for the zone and endpoint configuration for the clients.

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/satellite
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/satellite]# vim icinga2-client1.localdomain.conf

object Host "icinga2-client1.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.111"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/satellite]# vim icinga2-client2.localdomain.conf

object Host "icinga2-client2.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.112"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
}

Add services using command endpoint checks. Pin the apply rules to the satellite zone only.

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/satellite]# vim services.conf

apply Service "ping4" {
  check_command = "ping4"
  //check is executed on the satellite node
  assign where host.zone == "satellite" && host.address
}

apply Service "disk" {
  check_command = "disk"

  //specify where the check is executed
  command_endpoint = host.vars.client_endpoint

  assign where host.zone == "satellite" && host.vars.client_endpoint
}

Validate the configuration and restart Icinga 2 on the master node icinga2-master1.localdomain.

Open Icinga Web 2 and check the two newly created client hosts with two new services -- one executed locally (ping4) and one using command endpoint (disk).

Tip: It's a good idea to add health checks to make sure that your cluster notifies you in case of failure.

Best Practice

We've put together a collection of configuration examples from community feedback. If you like to share your tips and tricks with us, please join the community channels!

Global Zone for Config Sync

Global zones can be used to sync generic configuration objects to all nodes depending on them. Common examples are:

Templates which are imported into zone specific objects.
Command objects referenced by Host, Service, Notification objects.
Apply rules for services, notifications, dependencies and scheduled downtimes.
User objects referenced in notifications.
Group objects.
TimePeriod objects.

Plugin scripts and binaries cannot be synced, this is for Icinga 2 configuration files only. Use your preferred package repository and/or configuration management tool (Puppet, Ansible, Chef, etc.) for that.

Note: Checkable objects (hosts and services) cannot be put into a global zone. The configuration validation will terminate with an error.

The zone object configuration must be deployed on all nodes which should receive the global configuration files:

object Zone "global-templates" {
  global = true
}

Similar to the zone configuration sync you'll need to create a new directory in /etc/icinga2/zones.d:

[root@icinga2-master1.localdomain /]# mkdir -p /etc/icinga2/zones.d/global-templates

Next, add a new check command, for example:

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.d/global-templates/commands.conf

object CheckCommand "my-cmd" {
  //...
}

Restart the client(s) which should receive the global zone before before restarting the parent master/satellite nodes.

Then validate the configuration on the master node and restart Icinga 2.

Tip: You can copy the example configuration files located in /etc/icinga2/conf.d into your global zone.

Example:

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/conf.d
[root@icinga2-master1.localdomain /etc/icinga2/conf.d]# cp {commands,downtimes,groups,notifications,templates,timeperiods,users}.conf /etc/icinga2/zones.d/global-templates

Health Checks

In case of network failures or other problems, your monitoring might either have late check results or just send out mass alarms for unknown checks.

In order to minimize the problems caused by this, you should configure additional health checks.

The cluster check, for example, will check if all endpoints in the current zone and the directly connected zones are working properly:

object Service "cluster" {
    check_command = "cluster"
    check_interval = 5s
    retry_interval = 1s

    host_name = "icinga2-master1.localdomain"
}

The cluster-zone check will test whether the configured target zone is currently connected or not:

apply Service "child-health" {
  check_command = "cluster-zone"

  /* This follows the convention that the client zone name is the FQDN which is the same as the host object name. */
  vars.cluster_zone = host.name

  assign where host.vars.has_client
}

In case you cannot assign the cluster_zone attribute, add specific checks to your cluster:

object Service "cluster-zone-satellite" {
  check_command = "cluster-zone"
  check_interval = 5s
  retry_interval = 1s
  vars.cluster_zone = "satellite"

  host_name = "icinga2-master1.localdomain"
}

If you are using top down checks with command endpoint configuration, you can add a dependency which prevents notifications for all other failing services:

apply Dependency "health-check" to Service {
  parent_service_name = "child-health"

  states = [ OK ]
  disable_notifications = true

  assign where host.vars.has_client
  ignore where service.name == "child-health"

}

Windows Firewall

By default ICMP requests are disabled in the Windows firewall. You can change that by adding a new rule.

C:\WINDOWS\system32>netsh advfirewall firewall add rule name="ICMP Allow incoming V4 echo request" protocol=icmpv4:8,any dir=in action=allow

If your master/satellite nodes should actively connect to the Windows client you'll also need to ensure that port 5665 is enabled.

C:\WINDOWS\system32>netsh advfirewall firewall add rule name="Open port 5665 (Icinga 2)" dir=in action=allow protocol=TCP localport=5665

Windows Client and Plugins

The Icinga 2 package on Windows already provides several plugins. Detailed documentation is available for all check command definitions.

Add the following include statement on all your nodes (master, satellite, client):

vim /etc/icinga2/icinga2.conf

include <windows-plugins>

Based on the master with clients scenario we'll now add a local disk check.

First, add the client node as host object:

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/master
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim hosts.conf

object Host "icinga2-client2.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.112"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
  vars.os_type = "windows"
}

Next, add the disk check using command endpoint checks (details in the disk-windows documentation):

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim services.conf

apply Service "disk C:" {
  check_command = "disk-windows"

  vars.disk_win_path = "C:"

  //specify where the check is executed
  command_endpoint = host.vars.client_endpoint

  assign where host.vars.os_type == "windows" && host.vars.client_endpoint
}

Validate the configuration and restart Icinga 2.

[root@icinga2-master1.localdomain /]# icinga2 daemon -C
[root@icinga2-master1.localdomain /]# systemctl restart icinga2

Open Icinga Web 2 and check your newly added Windows disk check :)

If you want to add your own plugins please check this chapter for the requirements.

Windows Client and NSClient++

The Windows setup already allows you to install the NSClient++ package. In addition to the Windows plugins you can use the nscp-local commands provided by the Icinga Template Library (ITL).

Add the following include statement on all your nodes (master, satellite, client):

vim /etc/icinga2/icinga2.conf

include <nscp-local>

The CheckCommand definitions will automatically determine the installed path to the nscp.exe binary.

Based on the master with clients scenario we'll now add a local nscp check querying a given performance counter.

First, add the client node as host object:

[root@icinga2-master1.localdomain /]# cd /etc/icinga2/zones.d/master
[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim hosts.conf

object Host "icinga2-client1.localdomain" {
  check_command = "hostalive"
  address = "192.168.56.111"
  vars.client_endpoint = name //follows the convention that host name == endpoint name
  vars.os_type = "windows"
}

Next, add a performance counter check using command endpoint checks (details in the nscp-local-counter documentation):

[root@icinga2-master1.localdomain /etc/icinga2/zones.d/master]# vim services.conf

apply Service "nscp-local-counter-cpu" {
  check_command = "nscp-local-counter"
  command_endpoint = host.vars.client_endpoint

  vars.nscp_counter_name = "\\Processor(_total)\\% Processor Time"
  vars.nscp_counter_perfsyntax = "Total Processor Time"
  vars.nscp_counter_warning = 1
  vars.nscp_counter_critical = 5

  vars.nscp_counter_showall = true

  assign where host.vars.os_type == "windows" && host.vars.client_endpoint
}

Validate the configuration and restart Icinga 2.

[root@icinga2-master1.localdomain /]# icinga2 daemon -C
[root@icinga2-master1.localdomain /]# systemctl restart icinga2

Open Icinga Web 2 and check your newly added Windows NSClient++ check :)

Advanced Hints

You can find additional hints in this section if you prefer to go your own route with automating setups (setup, certificates, configuration).

High-Availability for Icinga 2 Features

All nodes in the same zone require that you enable the same features for high-availability (HA).

By default, the following features provide advanced HA functionality:

Checks (load balanced, automated failover).
Notifications (load balanced, automated failover).
DB IDO (Run-Once, automated failover).

High-Availability with Checks

All instances within the same zone (e.g. the master zone as HA cluster) must have the checker feature enabled.

Example:

# icinga2 feature enable checker

All nodes in the same zone load-balance the check execution. If one instance shuts down, the other nodes will automatically take over the remaining checks.

High-Availability with Notifications

All instances within the same zone (e.g. the master zone as HA cluster) must have the notification feature enabled.

Example:

# icinga2 feature enable notification

Notifications are load-balanced amongst all nodes in a zone. By default this functionality is enabled. If your nodes should send out notifications independently from any other nodes (this will cause duplicated notifications if not properly handled!), you can set enable_ha = false in the NotificationComponent feature.

High-Availability with DB IDO

All instances within the same zone (e.g. the master zone as HA cluster) must have the DB IDO feature enabled.

Example DB IDO MySQL:

# icinga2 feature enable ido-mysql

By default the DB IDO feature only runs on one node. All other nodes in the same zone disable the active IDO database connection at runtime. The node with the active DB IDO connection is not necessarily the zone master.

Note: The DB IDO HA feature can be disabled by setting the enable_ha attribute to false for the IdoMysqlConnection or IdoPgsqlConnection object on all nodes in the same zone.

All endpoints will enable the DB IDO feature and connect to the configured database and dump configuration, status and historical data on their own.

If the instance with the active DB IDO connection dies, the HA functionality will automatically elect a new DB IDO master.

The DB IDO feature will try to determine which cluster endpoint is currently writing to the database and bail out if another endpoint is active. You can manually verify that by running the following query command:

icinga=> SELECT status_update_time, endpoint_name FROM icinga_programstatus;
   status_update_time   | endpoint_name
------------------------+---------------
 2016-08-15 15:52:26+02 | icinga2-master1.localdomain
(1 Zeile)

This is useful when the cluster connection between endpoints breaks, and prevents data duplication in split-brain-scenarios. The failover timeout can be set for the failover_timeout attribute, but not lower than 60 seconds.

Endpoint Connection Direction

Nodes will attempt to connect to another node when its local Endpoint object configuration specifies a valid host attribute (FQDN or IP address).

Example for the master node icinga2-master1.localdomain actively connecting to the client node icinga2-client1.localdomain:

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.conf

//...

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.56.111" //the master actively tries to connect to the client
  log_duration = 0
}

Example for the client node icinga2-client1.localdomain not actively connecting to the master node icinga2-master1.localdomain:

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/zones.conf

//...

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
  log_duration = 0
}

It is not necessary that both the master and the client node establish two connections to each other. Icinga 2 will only use one connection and close the second connection if established.

Tip: Choose either to let master/satellite nodes connect to client nodes or vice versa.

Disable Log Duration for Command Endpoints

The replay log is a built-in mechanism to ensure that nodes in a distributed setup keep the same history (check results, notifications, etc.) when nodes are temporarily disconnected and then reconnect.

This functionality is not needed when a master/satellite node is sending check execution events to a client which is purely configured for command endpoint checks only.

The Endpoint object attribute log_duration can be lower or set to 0 to fully disable any log replay updates when the client is not connected.

Configuration on the master node icinga2-master1.localdomain:

[root@icinga2-master1.localdomain /]# vim /etc/icinga2/zones.conf

//...

object Endpoint "icinga2-client1.localdomain" {
  host = "192.168.56.111" //the master actively tries to connect to the client
  log_duration = 0
}

object Endpoint "icinga2-client2.localdomain" {
  host = "192.168.33.112" //the master actively tries to connect to the client
  log_duration = 0
}

Configuration on the client icinga2-client1.localdomain:

[root@icinga2-client1.localdomain /]# vim /etc/icinga2/zones.conf

//...

object Endpoint "icinga2-master1.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
  log_duration = 0
}

object Endpoint "icinga2-master2.localdomain" {
  //do not actively connect to the master by leaving out the 'host' attribute
  log_duration = 0
}

CSR auto-signing with HA and multiple Level Cluster

If you are using two masters in a High-Availability setup it can be necessary to allow both to sign requested certificates. Ensure to safely sync the following details in private:

TicketSalt constant in constants.conf.
var/lib/icinga2/ca directory.

This also helps if you are using a three level cluster and your client nodes are not able to reach the CSR auto-signing master node(s). Make sure that the directory permissions for /var/lib/icinga2/ca are secure (not world readable).

Do not expose these private keys to anywhere else. This is a matter of security.

Manual Certificate Creation

Choose the host which should store the certificate authority (one of the master nodes).

The first step is the creation of the certificate authority (CA) by running the following command as root user:

[root@icinga2-master1.localdomain /root]# icinga2 pki new-ca

Create a certificate signing request (CSR) for each node:

[root@icinga2-master1.localdomain /root]# icinga2 pki new-cert --cn icinga2-master1.localdomain \
  --key icinga2-master1.localdomain.key \
  --csr icinga2-master1.localdomain.csr

Sign the CSR with the previously created CA:

[root@icinga2-master1.localdomain /root]# icinga2 pki sign-csr --csr icinga2-master1.localdomain.csr --cert icinga2-master1.localdomain

Copy the host's certificate files and the public CA certificate to /etc/icinga2/pki:

[root@icinga2-master1.localdomain /root]# mkdir -p /etc/icinga2/pki
[root@icinga2-master1.localdomain /root]# cp icinga2-master1.localdomain.{crt,key} /etc/icinga2/pki
[root@icinga2-master1.localdomain /root]# cp /var/lib/icinga2/ca/ca.crt /etc/icinga2/pki

Ensure that proper permissions are set (replace icinga with the Icinga 2 daemon user):

[root@icinga2-master1.localdomain /root]# chown -R icinga:icinga /etc/icinga2/pki
[root@icinga2-master1.localdomain /root]# chmod 600 /etc/icinga2/pki/*.key
[root@icinga2-master1.localdomain /root]# chmod 644 /etc/icinga2/pki/*.crt

The CA public and private key are stored in the /var/lib/icinga2/ca directory. Keep this path secure and include it in your backups.

Example for creating multiple certificates at once:

[root@icinga2-master1.localdomain /etc/icinga2/pki]# for node in icinga2-master1.localdomain icinga2-master2.localdomain icinga2-satellite1.localdomain; do icinga2 pki new-cert --cn $node --csr $node.csr --key $node.key; done
information/base: Writing private key to 'icinga2-master1.localdomain.key'.
information/base: Writing certificate signing request to 'icinga2-master1.localdomain.csr'.
information/base: Writing private key to 'icinga2-master2.localdomain.key'.
information/base: Writing certificate signing request to 'icinga2-master2.localdomain.csr'.
information/base: Writing private key to 'icinga2-satellite1.localdomain.key'.
information/base: Writing certificate signing request to 'icinga2-satellite1.localdomain.csr'.

[root@icinga2-master1.localdomain /etc/icinga2/pki]# for node in icinga2-master1.localdomain icinga2-master2.localdomain icinga2-satellite1.localdomain; do sudo icinga2 pki sign-csr --csr $node.csr --cert $node.crt; done
information/pki: Writing certificate to file 'icinga2-master1.localdomain.crt'.
information/pki: Writing certificate to file 'icinga2-master2.localdomain.crt'.
information/pki: Writing certificate to file 'icinga2-satellite1.localdomain.crt'.

Automation

These hints should get you started with your own automation tools (Puppet, Ansible, Chef, Salt, etc.) or custom scripts for automated setup.

These are collected best practices from various community channels.

Silent Windows setup
Node Setup CLI command with parameters

If you prefer an alternate method, we still recommend leaving all the Icinga 2 features intact (e.g. icinga2 feature enable api). You should also use well known and documented default configuration file locations (e.g. zones.conf). This will tremendously help when someone is trying to help in the community channels.

Silent Windows Setup

If you want to install the client silently/unattended, use the /qn modifier. The installation should not trigger a restart, but if you want to be completly sure, you can use the /norestart modifier.

C:> msiexec /i C:\Icinga2-v2.5.0-x86.msi /qn /norestart

Once the setup is completed you can use the node setup cli command too.

Node Setup using CLI Parameters

Instead of using the node wizard CLI command, there is an alternative node setup command available which has some prerequisites.

Note: The CLI command can be used on Linux/Unix and Windows operating systems. The graphical Windows setup wizard actively uses these CLI commands.

Node Setup on the Master Node

In case you want to setup a master node you must add the --master parameter to the node setup CLI command. In addition to that the --cn can optionally be passed (defaults to the FQDN).

Parameter	Description
Common name (CN)	Optional. Specified with the `--cn` parameter. By convention this should be the host's FQDN. Defaults to the FQDN.
Listen on	Optional. Specified with the `--listen` parameter. Syntax is `host,port`.

Example:

[root@icinga2-master1.localdomain /]# icinga2 node setup --master

In case you want to bind the ApiListener object to a specific host/port you can specify it like this:

--listen 192.68.56.101,5665

Node Setup with Satellites/Clients

Make sure that the /etc/icinga2/pki exists and is owned by the icinga user (or the user Icinga 2 is running as).

[root@icinga2-client1.localdomain /]# mkdir -p /etc/icinga2/pki
[root@icinga2-client1.localdomain /]# chown -R icinga:icinga /etc/icinga2/pki

First you'll need to generate a new local self-signed certificate. Pass the following details to the pki new-cert CLI command:

Parameter	Description
Common name (CN)	Required. By convention this should be the host's FQDN. Defaults to the FQDN.
Client certificate files	Required. These generated files will be put into the specified location (--key and --file). By convention this should be using `/etc/icinga2/pki` as directory.

Example:

[root@icinga2-client1.localdomain /]# icinga2 pki new-cert --cn icinga2-client1.localdomain \
--key /etc/icinga2/pki/icinga2-client1.localdomain.key \
--cert /etc/icinga2/pki/icinga2-client1.localdomain.crt

Request the master certificate from the master host (icinga2-master1.localdomain) and store it as trusted-master.crt. Review it and continue.

Pass the following details to the pki save-cert CLI command:

Parameter	Description
Client certificate files	Required. Pass the previously generated files using the `--key` and `--cert` parameters.
Trusted master certicate	Required. Store the master's certificate file. Manually verify that you're trusting it.
Master host	Required. FQDN or IP address of the master host.

Example:

[root@icinga2-client1.localdomain /]# icinga2 pki save-cert --key /etc/icinga2/pki/icinga2-client1.localdomain.key \
--cert /etc/icinga2/pki/icinga2-client1.localdomain.crt \
--trustedcert /etc/icinga2/pki/trusted-master.crt \
--host icinga2-master1.localdomain

Continue with the additional node setup step. Specify a local endpoint and zone name (icinga2-client1.localdomain) and set the master host (icinga2-master1.localdomain) as parent zone configuration. Specify the path to the previously stored trusted master certificate.

Pass the following details to the node setup CLI command:

Parameter	Description
Request ticket	Required. Add the previously generated ticket number.
Trusted master certicate	Required. Add the previously fetched trusted master certificate (this step means that you've verified its origin).
Master endpoint	Required. Specify the master's endpoint name.
Client zone name	Required. Specify the client's zone name.
Master host	Required. FQDN or IP address of the master host.
Accept config	Optional. Whether this node accepts configuration sync from the master node (required for config sync mode).
Accept commands	Optional. Whether this node accepts command execution messages from the master node (required for command endpoint mode).

Example:

[root@icinga2-client1.localdomain /]# icinga2 node setup --ticket ead2d570e18c78abf285d6b85524970a0f69c22d \
--endpoint icinga2-master1.localdomain \
--zone icinga2-client1.localdomain \
--master_host icinga2-master1.localdomain \
--trustedcert /etc/icinga2/pki/trusted-master.crt \
--accept-commands --accept-config

In case the client should connect to the master node, you'll need to modify the --endpoint parameter using the format cn,host,port:

--endpoint icinga2-master1.localdomain,192.168.56.101,5665

Restart Icinga 2 afterwards:

# service icinga2 restart

You can find additional best practices below.

Add an additional global zone. Please note the >> append mode.

[root@icinga2-client1.localdomain /]# cat <<EOF >>/etc/icinga2/zones.conf
object Zone "global-templates" {
  global = true
}
EOF

If this client node is configured as remote command endpoint execution you can safely disable the checker feature. The node setup CLI command already disabled the notification feature.

[root@icinga2-client1.localdomain /]# icinga2 feature disable checker

Disable "conf.d" inclusion if this is a top down configured client.

[root@icinga2-client1.localdomain /]# sed -i 's/include_recursive "conf.d"/\/\/include_recursive "conf.d"/g' /etc/icinga2/icinga2.conf

Optional: Add an ApiUser object configuration for remote troubleshooting.

[root@icinga2-client1.localdomain /]# cat <<EOF >/etc/icinga2/conf.d/api-users.conf
object ApiUser "root" {
  password = "clientsupersecretpassword"
  permissions = ["*"]
}
EOF

In case you've previously disabled the "conf.d" directory only add the file file conf.d/api-users.conf:

[root@icinga2-client1.localdomain /]# echo 'include "conf.d/api-users.conf"' >> /etc/icinga2/icinga2.conf

Finally restart Icinga 2.

[root@icinga2-client1.localdomain /]# systemctl restart icinga2

Your automation tool must then configure master node in the meantime. Add the global zone global-templates in case it did not exist.

# cat <<EOF >>/etc/icinga2/zones.conf
object Endpoint "icinga2-client1.localdomain" {
  //client connects itself
}

object Zone "icinga2-client1.localdomain" {
  endpoints = [ "icinga2-client1.localdomain" ]
  parent = "master"
}

object Zone "global-templates" {
  global = true
}
EOF

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Distributed Monitoring with Master, Satellites, and Clients

Roles: Master, Satellites, and Clients

Zones

Endpoints

ApiListener

Conventions

Security

Master Setup

Client/Satellite Setup

CSR Auto-Signing

Client/Satellite Linux Setup

Client/Satellite Windows Setup

Configuration Modes

Top Down

Top Down Command Endpoint

Top Down Config Sync

Bottom Up Import

Scenarios

Master with Clients

High-Availability Master with Clients

Three Levels with Master, Satellites, and Clients

Best Practice

Global Zone for Config Sync

Health Checks

Windows Firewall

Windows Client and Plugins

Windows Client and NSClient++

Advanced Hints

High-Availability for Icinga 2 Features

High-Availability with Checks

High-Availability with Notifications

High-Availability with DB IDO

Endpoint Connection Direction

Disable Log Duration for Command Endpoints

CSR auto-signing with HA and multiple Level Cluster

Manual Certificate Creation

Automation

Silent Windows Setup

Node Setup using CLI Parameters

Node Setup on the Master Node

Node Setup with Satellites/Clients

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