mirror of https://github.com/Icinga/icinga2.git
86 lines
2.9 KiB
Markdown
86 lines
2.9 KiB
Markdown
## <a id="hosts-services"></a> Hosts and Services
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Icinga 2 can be used to monitor the availability of hosts and services. Services
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can be virtually anything which can be checked in some way:
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* Network services (HTTP, SMTP, SNMP, SSH, etc.)
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* Printers
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* Switches / Routers
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* Temperature Sensors
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* Other local or network-accessible services
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Host objects provide a mechanism to group services that are running
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on the same physical device.
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Here is an example of a host object which defines two child services:
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object Host "my-server1" {
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macros.address = "10.0.0.1",
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check = "ping4"
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}
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apply Service "ping4" {
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check_command = "ping4"
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assign where host.name == "my-server1"
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}
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apply Service "http" {
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check_command = "http_ip"
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assign where host.name == "my-server1"
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}
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The example host `my-server1` creates two services which belong to this host:
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`ping4` and `http`.
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It also specifies that the host should inherit its availability state from the
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`ping4` service.
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> **Note**
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>
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> In Icinga 1.x hosts had their own check command, check interval and
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> notification settings. Instead, in Icinga 2 hosts inherit their state
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> from one of its child services. No checks are performed for the host
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> itself.
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The `address` macro is used by check commands to determine which network
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address is associated with the host object.
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### <a id="host-states"></a> Host States
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Hosts inherit their state from the host check service that is specified using
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the `check` attribute.
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Hosts can be in any of the following states:
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Name | Description
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------------|--------------
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UP | The host is available.
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DOWN | The host is unavailable.
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UNREACHABLE | At least one of the host's dependencies (e.g. its upstream router) is unavailable causing the host to be unreachable.
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### <a id="service-states"></a> Service States
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Services can be in any of the following states:
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Name | Description
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------------|--------------
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OK | The service is working properly.
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WARNING | The service is experiencing some problems but is still considered to be in working condition.
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CRITICAL | The service is in a critical state.
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UNKNOWN | The check could not determine the service's state.
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### <a id="hard-soft-states"></a> Hard and Soft States
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When detecting a problem with a service Icinga re-checks the service a number of
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times (based on the `max_check_attempts` and `retry_interval` settings) before sending
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notifications. This ensures that no unnecessary notifications are sent for
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transient failures. During this time the service is in a `SOFT` state.
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After all re-checks have been executed and the service is still in a non-OK
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state the service switches to a `HARD` state and notifications are sent.
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Name | Description
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------------|--------------
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HARD | The host/service's state hasn't recently changed.
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SOFT | The host/service has recently changed state and is being re-checked.
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