## Macros > **Note** > > There is a limited set of special [global constants](#global-constants) which can be re-used and > also partly overridden such as `IcingaEnableChecks`. ### Runtime Macros Macros may be used in command definitions to dynamically change how the command is executed. Additionally there are Icinga 2 features for example the `PerfDataWriter` using the available runtime macros for output formatting. > **Note** > > Macros are evaluated at runtime when executing a command. These macros cannot be > used inside the configuration objects to add references or similar unless > stated otherwise. Here is an example of a command definition which uses user-defined macros: object CheckCommand "my-ping" inherits "plugin-check-command" { command = [ "$plugindir$/check_ping", "-4", "-H", "$address$", "-w", "$wrta$,$wpl$%", "-c", "$crta$,$cpl$%", "-p", "$packets$", "-t", "$timeout$" ], macros = { wrta = 100, wpl = 5, crta = 200, cpl = 15, packets = 5, timeout = 0 } } > **Note** > > If you have previously used Icinga 1.x you may already be familiar with > user and argument macros (e.g., `USER1` or `ARG1`). Unlike in Icinga 1.x macros > may have arbitrary names and arguments are no longer specified in the > `check_command` setting. Macro names must be enclosed in two `$` signs, e.g. `$plugindir$`. When using the `$` sign as single character, you need to escape it with an additional dollar sign (`$$`). ### Runtime Macro Evaluation Order When executing commands Icinga 2 checks the following objects in this order to look up macros: 1. User object (only for notifications) 2. Service object 3. Host object 4. Command object 5. Global macros in the IcingaMacros constant This execution order allows you to define default values for macros in your command objects. The `my-ping` command shown above uses this to set default values for some of the latency thresholds and timeouts. When using the `my-ping` command you can override all or some of the macros in the service definition like this: object Host "my-server1" { services["ping"] = { check_command = "my-ping", macros["packets"] = 10 // Overrides the default value of 5 given in the command }, macros["address"] = "10.0.0.1" } If a macro isn't defined anywhere an empty value is used and a warning is emitted to the Icinga 2 log. > **Note** > > Macros in capital letters (e.g. `HOSTNAME`) are reserved for use by Icinga 2 > and should not be overwritten by users. > **Best Practice** > > By convention every host should have an `address` macro. Hosts > which have an IPv6 address should also have an `address6` macro. The `plugindir` macro should be set to the path of your check plugins. The `/etc/icinga2/conf.d/macros.conf` file is usually used to define global macros including this one. #### Custom Variables as Runtime Macros Custom variables are made available as macros using an underscore and the object type in uppercase characters as additional prefix. For example `_HOST`name "_HOST" where is the name of the custom variable. #### Runtime Macro Evaluation Order in Cluster Mode These macros are evaluated and calculated upon command execution on each node. If a cluster node defines additional macros overriding the default tuples, the calculated macro values will be different and affect only the node executing the command. Node 1: const IcingaMacros = { plugindir = "/usr/lib/icinga/plugins" } Node 2: const IcingaMacros = { plugindir = "/usr/lib/monitoring/plugins" } CheckCommand definition: object CheckCommand "whatever" inherits "plugin-check-command" { command = "$plugindir$/check_whatever" } On Node 1, this will be evaluated into `/usr/lib/icinga/plugins/check_whatever`. On Node 2, Icinga 2 will attempt to execute `/usr/lib/icinga/monitoring/check_whatever` instead. ### Host Runtime Macros The following host macros are available in all commands that are executed for hosts or services: Name | Description -----------------------|-------------- HOSTNAME | The name of the host object. HOSTDISPLAYNAME | The value of the `display_name` attribute. HOSTALIAS | This is an alias for the `HOSTDISPLAYNAME` macro. HOSTSTATE | The host's current state. Can be one of `UNREACHABLE`, `UP` and `DOWN`. HOSTSTATEID | The host's current state. Can be one of `0` (up), `1` (down) and `2` (unreachable). HOSTSTATETYPE | The host's current state type. Can be one of `SOFT` and `HARD`. HOSTATTEMPT | The current check attempt number. MAXHOSTATTEMPT | The maximum number of checks which are executed before changing to a hard state. LASTHOSTSTATE | The host's previous state. Can be one of `UNREACHABLE`, `UP` and `DOWN`. LASTHOSTSTATEID | The host's previous state. Can be one of `0` (up), `1` (down) and `2` (unreachable). LASTHOSTSTATETYPE | The host's previous state type. Can be one of `SOFT` and `HARD`. LASTHOSTSTATECHANGE | The last state change's timestamp. HOSTDURATIONSEC | The time since the last state change. HOSTLATENCY | The host's check latency. HOSTEXECUTIONTIME | The host's check execution time. HOSTOUTPUT | The last check's output. HOSTPERFDATA | The last check's performance data. LASTHOSTCHECK | The timestamp when the last check was executed. HOSTADDRESS | This is an alias for the `address` macro. If the `address` macro is not defined the host object's name is used instead. HOSTADDRESS6 | This is an alias for the `address6` macro. If the `address` macro is not defined the host object's name is used instead. > **Note** > > `HOSTADDRESS` and `HOSTADDRESS6` macros are available as legacy macros. The > Icinga 2 Template Library (`ITL`) examples use the `$address$` macro instead > requiring that macro key to be defined. Custom variables are made available as macros with the name "_HOST" where is the name of the custom variable. ### Service Runtime Macros The following service macros are available in all commands that are executed for services: Name | Description -----------------------|-------------- SERVICEDESC | The short name of the service object. SERVICEDISPLAYNAME | The value of the `display_name` attribute. SERVICECHECKCOMMAND | This is an alias for the `SERVICEDISPLAYNAME` macro. SERVICESTATE | The service's current state. Can be one of `OK`, `WARNING`, `CRITICAL` and `UNKNOWN`. SERVICESTATEID | The service's current state. Can be one of `0` (ok), `1` (warning), `2` (critical) and `3` (unknown). SERVICESTATETYPE | The service's current state type. Can be one of `SOFT` and `HARD`. SERVICEATTEMPT | The current check attempt number. MAXSERVICEATTEMPT | The maximum number of checks which are executed before changing to a hard state. LASTSERVICESTATE | The service's previous state. Can be one of `OK`, `WARNING`, `CRITICAL` and `UNKNOWN`. LASTSERVICESTATEID | The service's previous state. Can be one of `0` (ok), `1` (warning), `2` (critical) and `3` (unknown). LASTSERVICESTATETYPE | The service's previous state type. Can be one of `SOFT` and `HARD`. LASTSERVICESTATECHANGE | The last state change's timestamp. SERVICEDURATIONSEC | The time since the last state change. SERVICELATENCY | The service's check latency. SERVICEEXECUTIONTIME | The service's check execution time. SERVICEOUTPUT | The last check's output. SERVICEPERFDATA | The last check's performance data. LASTSERVICECHECK | The timestamp when the last check was executed. TOTALHOSTSERVICES | Number of services associated with the host. TOTALHOSTSERVICESOK | Number of services associated with the host which are in an `OK` state. TOTALHOSTSERVICESWARNING | Number of services associated with the host which are in a `WARNING` state. TOTALHOSTSERVICESUNKNOWN | Number of services associated with the host which are in an `UNKNOWN` state. TOTALHOSTSERVICESCRITICAL | Number of services associated with the host which are in a `CRITICAL` state. Custom variables are made available as macros with the name "_SERVICE" where is the name of the custom variable. ### User Runtime Macros The following macros are available in all commands that are executed for users: Name | Description -----------------------|-------------- USERNAME | The name of the user object. USERDISPLAYNAME | The value of the display_name attribute. USEREMAIL | This is an alias for the `email` macro. USERPAGER | This is an alias for the `pager` macro. Custom variables are made available as macros with the name "_USER" and "_CONTACT" where is the name of the custom variable. "_CONTACT" ### Notification Runtime Macros Custom variables are made available as macros with the name "_NOTIFICATION" where is the name of the custom variable. ### Global Runtime Macros The following macros are available in all executed commands: Name | Description -----------------------|-------------- TIMET | Current UNIX timestamp. LONGDATETIME | Current date and time including timezone information. Example: `2014-01-03 11:23:08 +0000` SHORTDATETIME | Current date and time. Example: `2014-01-03 11:23:08` DATE | Current date. Example: `2014-01-03` TIME | Current time including timezone information. Example: `11:23:08 +0000` ### Runtime Macros as Environment Variables The `export_macros` command object attribute requires a list of macros which should be exported as environment variables prior to executing the command. This is useful for example for hiding sensitive information on the command line output when passing credentials to database checks: object CheckCommand "mysql-health" inherits "plugin-check-command" { command = "$plugindir$/check_mysql -H $address$ -d $db$", /* default macro values */ macros = { "MYSQLUSER" = "icinga_check", "MYSQLPASS" = "1c1ng42r0xx" }, export_macros = [ "MYSQLUSER", "MYSQLPASS" ] } ### Configuration Macros Icinga 2 allows you to define constants which can be used in a limited scope. For example, constant expressions can reference a pre-defined global constant variable and calculate a value for the service check interval. Example: const MyCheckInterval = 10m ... { check_interval = MyCheckInterval / 2.5 } More details in the chapter [Constant Expressions](#constant-expressions).