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Language Reference

Object Definition

Icinga 2 features an object-based configuration format. You can define new objects using the object keyword:

object Host "host1.example.org" {
  display_name = "host1"

  address = "192.168.0.1"
  address6 = "::1"
}

In general you need to write each statement on a new line. Expressions started with {, ( and [ extend until the matching closing character and can be broken up into multiple lines.

Alternatively you can write multiple statements on a single line by separating them with a semicolon:

object Host "host1.example.org" {
  display_name = "host1"

  address = "192.168.0.1"; address6 = "::1"
}

Each object is uniquely identified by its type (Host) and name (host1.example.org). Some types have composite names, e.g. the Service type which uses the host_name attribute and the name you specified to generate its object name.

Exclamation marks (!) are not permitted in object names.

Objects can contain a comma-separated list of property declarations. Instead of commas semicolons may also be used. The following data types are available for property values:

Expressions

The following expressions can be used on the right-hand side of assignments.

Numeric Literals

A floating-point number.

Example:

27.3

Duration Literals

Similar to floating-point numbers except for the fact that they support suffixes to help with specifying time durations.

Example:

2.5m

Supported suffixes include ms (milliseconds), s (seconds), m (minutes), h (hours) and d (days).

Duration literals are converted to seconds by the config parser and are treated like numeric literals.

String Literals

A string.

Example:

"Hello World!"

Certain characters need to be escaped. The following escape sequences are supported:

Character	Escape sequence
"	\"
\	\\
<TAB>	\t
<CARRIAGE-RETURN>	\r
<LINE-FEED>	\n
<BEL>	\b
<FORM-FEED>	\f

In addition to these pre-defined escape sequences you can specify arbitrary ASCII characters using the backslash character (\) followed by an ASCII character in octal encoding.

Multi-line String Literals

Strings spanning multiple lines can be specified by enclosing them in {{{ and }}}.

Example:

{{{This
is
a multi-line
string.}}}

Unlike in ordinary strings special characters do not have to be escaped in multi-line string literals.

Boolean Literals

The keywords true and false are used to denote truth values.

Null Value

The null keyword can be used to specify an empty value.

Dictionary

An unordered list of key-value pairs. Keys must be unique and are compared in a case-sensitive manner.

Individual key-value pairs must either be comma-separated or on separate lines. The comma after the last key-value pair is optional.

Example:

{
  address = "192.168.0.1"
  port = 443
}

Identifiers may not contain certain characters (e.g. space) or start with certain characters (e.g. digits). If you want to use a dictionary key that is not a valid identifier you can enclose the key in double quotes.

Array

An ordered list of values.

Individual array elements must be comma-separated. The comma after the last element is optional.

Example:

[ "hello", 42 ]

An array may simultaneously contain values of different types, such as strings and numbers.

Operators

The following operators are supported in expressions. The operators are by descending precedence.

Operator	Precedence	Examples (Result)	Description
()	1	(3 + 3) * 5	Groups sub-expressions
()	1	Math.random()	Calls a function
[]	1	a[3]	Array subscript
.	1	a.b	Element access
!	2	!"Hello" (false), !false (true)	Logical negation of the operand
~	2	~true (false)	Bitwise negation of the operand

   | 2          | +3                                            | Unary plus

   | 2          | -3                                            | Unary minus

   | 3          | 5m * 10 (3000)                                | Multiplies two numbers

/ | 3 | 5m / 5 (60) | Divides two numbers % | 3 | 17 % 12 (5) | Remainder after division

   | 4          | 1 + 3 (4), "hello " + "world" ("hello world") | Adds two numbers; concatenates strings

   | 4          | 3 - 1 (2)                                     | Subtracts two numbers

<< | 5 | 4 << 8 (1024) | Left shift

  | 5          | 1024 >> 4 (64)                                | Right shift

< | 6 | 3 < 5 (true) | Less than

   | 6         | 3 > 5 (false)                                 | Greater than

<= | 6 | 3 <= 3 (true) | Less than or equal

= | 6 | 3 >= 3 (true) | Greater than or equal in | 7 | "foo" in [ "foo", "bar" ] (true) | Element contained in array !in | 7 | "foo" !in [ "bar", "baz" ] (true) | Element not contained in array == | 8 | "hello" == "hello" (true), 3 == 5 (false) | Equal to != | 8 | "hello" != "world" (true), 3 != 3 (false) | Not equal to & | 9 | 7 & 3 (3) | Binary AND ^ | 10 | 17 ^ 12 (29) | Bitwise XOR | | 11 | 2 | 3 (3) | Binary OR && | 13 | true && false (false), 3 && 7 (7), 0 && 7 (0) | Logical AND || | 14 | true || false (true), 0 || 7 (7)| Logical OR = | 12 | a = 3 | Assignment => | 15 | x => x * x (function with arg x) | Lambda, for loop

Function Calls

Functions can be called using the () operator:

const MyGroups = [ "test1", "test" ]

{
  check_interval = len(MyGroups) * 1m
}

A list of available functions is available in the Library Reference chapter.

Assignments

In addition to the = operator shown above a number of other operators to manipulate attributes are supported. Here's a list of all available operators:

Operator =

Sets an attribute to the specified value.

Example:

{
  a = 5
  a = 7
}

In this example a has the value 7 after both instructions are executed.

Operator +=

The += operator is a shortcut. The following expression:

{
  a = [ "hello" ]
  a += [ "world" ]
}

is equivalent to:

{
  a = [ "hello" ]
  a = a + [ "world" ]
}

Operator -=

The -= operator is a shortcut. The following expression:

{
  a = 10
  a -= 5
}

is equivalent to:

{
  a = 10
  a = a - 5
}

Operator *=

The *= operator is a shortcut. The following expression:

{
  a = 60
  a *= 5
}

is equivalent to:

{
  a = 60
  a = a * 5
}

Operator /=

The /= operator is a shortcut. The following expression:

{
  a = 300
  a /= 5
}

is equivalent to:

{
  a = 300
  a = a / 5
}

Indexer

The indexer syntax provides a convenient way to set dictionary elements.

Example:

{
  hello.key = "world"
}

Example (alternative syntax):

{
  hello["key"] = "world"
}

This is equivalent to writing:

{
  hello += {
    key = "world"
  }
}

If the hello attribute does not already have a value it is automatically initialized to an empty dictionary.

Template Imports

Objects can import attributes from other objects.

Example:

template Host "default-host" {
  vars.colour = "red"
}

template Host "test-host" {
  import "default-host"

  vars.colour = "blue"
}

object Host "localhost" {
  import "test-host"

  address = "127.0.0.1"
  address6 = "::1"
}

The default-host and test-host objects are marked as templates using the template keyword. Unlike ordinary objects templates are not instantiated at run-time. Parent objects do not necessarily have to be templates, however in general they are.

The vars dictionary for the localhost object contains all three custom attributes and the custom attribute colour has the value "blue".

Parent objects are resolved in the order they're specified using the import keyword.

Constants

Global constants can be set using the const keyword:

const VarName = "some value"

Once defined a constant can be accessed from any file. Constants cannot be changed once they are set.

Icinga 2 provides a number of special global constants. Some of them can be overridden using the --define command line parameter:

Variable	Description
PrefixDir	Read-only. Contains the installation prefix that was specified with cmake -DCMAKE_INSTALL_PREFIX. Defaults to "/usr/local".
SysconfDir	Read-only. Contains the path of the sysconf directory. Defaults to PrefixDir + "/etc".
ZonesDir	Read-only. Contains the path of the zones.d directory. Defaults to SysconfDir + "/zones.d".
LocalStateDir	Read-only. Contains the path of the local state directory. Defaults to PrefixDir + "/var".
RunDir	Read-only. Contains the path of the run directory. Defaults to LocalStateDir + "/run".
PkgDataDir	Read-only. Contains the path of the package data directory. Defaults to PrefixDir + "/share/icinga2".
StatePath	Read-write. Contains the path of the Icinga 2 state file. Defaults to LocalStateDir + "/lib/icinga2/icinga2.state".
ObjectsPath	Read-write. Contains the path of the Icinga 2 objects file. Defaults to LocalStateDir + "/cache/icinga2/icinga2.debug".
PidPath	Read-write. Contains the path of the Icinga 2 PID file. Defaults to RunDir + "/icinga2/icinga2.pid".
Vars	Read-write. Contains a dictionary with global custom attributes. Not set by default.
NodeName	Read-write. Contains the cluster node name. Set to the local hostname by default.
ApplicationType	Read-write. Contains the name of the Application type. Defaults to "icinga/IcingaApplication".
EnableNotifications	Read-write. Whether notifications are globally enabled. Defaults to true.
EnableEventHandlers	Read-write. Whether event handlers are globally enabled. Defaults to true.
EnableFlapping	Read-write. Whether flap detection is globally enabled. Defaults to true.
EnableHostChecks	Read-write. Whether active host checks are globally enabled. Defaults to true.
EnableServiceChecks	Read-write. Whether active service checks are globally enabled. Defaults to true.
EnablePerfdata	Read-write. Whether performance data processing is globally enabled. Defaults to true.
UseVfork	Read-write. Whether to use vfork(). Only available on *NIX. Defaults to true.
RunAsUser	Read-write. Defines the user the Icinga 2 daemon is running as. Used in the `init.conf` configuration file.
RunAsGroup	Read-write. Defines the group the Icinga 2 daemon is running as. Used in the `init.conf` configuration file.

Apply

The apply keyword can be used to create new objects which are associated with another group of objects.

apply Service "ping" to Host {
  import "generic-service"

  check_command = "ping4"

  assign where host.name == "localhost"
}

In this example the assign where condition is a boolean expression which is evaluated for all objects of type Host and a new service with name "ping" is created for each matching host. Expression operators may be used in assign where conditions.

The to keyword and the target type may be omitted if there is only one target type, e.g. for the Service type.

Depending on the object type used in the apply expression additional local variables may be available for use in the where condition:

Source Type	Target Type	Variables
Service	Host	host
Dependency	Host	host
Dependency	Service	host, service
Notification	Host	host
Notification	Service	host, service
ScheduledDowntime	Host	host
ScheduledDowntime	Service	host, service

Any valid config attribute can be accessed using the host and service variables. For example, host.address would return the value of the host's "address" attribute - or null if that attribute isn't set.

Group Assign

Group objects can be assigned to specific member objects using the assign where and ignore where conditions.

object HostGroup "linux-servers" {
  display_name = "Linux Servers"

  assign where host.vars.os == "Linux"
}

In this example the assign where condition is a boolean expression which is evaluated for all objects of the type Host. Each matching host is added as member to the host group with the name "linux-servers". Membership exclusion can be controlled using the ignore where condition. Expression operators may be used in assign where and ignore where conditions.

Source Type	Variables
HostGroup	host
ServiceGroup	host, service
UserGroup	user

Boolean Values

The assign where, ignore where, if and while statements, the ! operator as well as the bool() function convert their arguments to a boolean value based on the following rules:

Description	Example Value	Boolean Value
Empty value	null	false
Zero	0	false
Non-zero integer	-23945	true
Empty string	""	false
Non-empty string	"Hello"	true
Empty array	[]	false
Non-empty array	[ "Hello" ]	true
Empty dictionary	{}	false
Non-empty dictionary	{ key = "value" }	true

For a list of supported expression operators for assign where and ignore where statements, see expression operators.

Comments

The Icinga 2 configuration format supports C/C++-style and shell-style comments.

Example:

/*
 This is a comment.
 */
object Host "localhost" {
  check_interval = 30 // this is also a comment.
  retry_interval = 15 # yet another comment
}

Includes

Other configuration files can be included using the include directive. Paths must be relative to the configuration file that contains the include directive.

Example:

include "some/other/file.conf"
include "conf.d/*.conf"

Wildcard includes are not recursive.

Icinga also supports include search paths similar to how they work in a C/C++ compiler:

include <itl>

Note the use of angle brackets instead of double quotes. This causes the config compiler to search the include search paths for the specified file. By default $PREFIX/share/icinga2/include is included in the list of search paths. Additional include search paths can be added using command-line options.

Wildcards are not permitted when using angle brackets.

Recursive Includes

The include_recursive directive can be used to recursively include all files in a directory which match a certain pattern.

Example:

include_recursive "conf.d", "*.conf"
include_recursive "templates"

The first parameter specifies the directory from which files should be recursively included.

The file names need to match the pattern given in the second parameter. When no pattern is specified the default pattern "*.conf" is used.

Library directive

The library directive can be used to manually load additional libraries. Libraries can be used to provide additional object types and functions.

Example:

library "snmphelper"

Functions

Functions can be defined using the function keyword.

Example:

function multiply(a, b) {
  return a * b
}

When encountering the return keyword further execution of the function is terminated and the specified value is supplied to the caller of the function:

log(multiply(3, 5))

In this example the multiply function we declared earlier is invoked with two arguments (3 and 5). The function computes the product of those arguments and makes the result available to the function's caller.

When no value is supplied for the return statement the function returns null.

Functions which do not have a return statement have their return value set to the value of the last expression which was performed by the function. For example, we could have also written our multiply function like this:

function multiply(a, b) {
  a * b
}

Anonymous functions can be created by omitting the name in the function definition. The resulting function object can be used like any other value:

var fn = function() { 3 }

fn() /* Returns 3 */

Lambda Expressions

Functions can also be declared using the alternative lambda syntax.

Example:

f = (x) => x * x

Multiple statements can be used by putting the function body into braces:

f = (x) => {
  log("Lambda called")
  x * x
}

Just like with ordinary functions the return value is the value of the last statement.

For lambdas which take exactly one argument the braces around the arguments can be omitted:

f = x => x * x

Abbreviated Lambda Syntax

Lambdas which take no arguments can also be written using the abbreviated lambda syntax.

Example:

f = {{ 3 }}

This creates a new function which returns the value 3.

Variable Scopes

When setting a variable Icinga checks the following scopes in this order whether the variable already exists there:

Local Scope
this Scope
Global Scope

The local scope contains variables which only exist during the invocation of the current function, object or apply statement. Local variables can be declared using the var keyword:

function multiply(a, b) {
  var temp = a * b
  return temp
}

Each time the multiply function is invoked a new temp variable is used which is in no way related to previous invocations of the function.

When setting a variable which has not previously been declared as local using the var keyword the this scope is used.

The this scope refers to the current object which the function or object/apply statement operates on.

object Host "localhost" {
  check_interval = 5m
}

In this example the this scope refers to the "localhost" object. The check_interval attribute is set for this particular host.

You can explicitly access the this scope using the this keyword:

object Host "localhost" {
  var check_interval = 5m

  /* This explicitly specifies that the attribute should be set
   * for the host, if we had omitted `this.` the (poorly named)
   * local variable `check_interval` would have been modified instead.
   */
  this.check_interval = 1m

}

Similarly the keywords locals and globals are available to access the local and global scope.

Functions also have a this scope. However unlike for object/apply statements the this scope for a function is set to whichever object was used to invoke the function. Here's an example:

 hm = {
   h_word = null
	 
   function init(word) {
     h_word = word
   }
 }
 
 /* Let's invoke the init() function */
 hm.init("hello")

We're using hm.init to invoke the function which causes the value of hm to become the this scope for this function call.

Conditional Statements

Sometimes it can be desirable to only evaluate statements when certain conditions are met. The if/else construct can be used to accomplish this.

Example:

a = 3

if (a < 5) {
  a *= 7
} else {
  a *= 2
}

An if/else construct can also be used in place of any other value. The value of an if/else statement is the value of the last statement which was evaluated for the branch which was taken:

a = if (true) {
  log("Taking the 'true' branch")
  7 * 3
} else {
  log("Taking the 'false' branch")
  9
}

This example prints the log message "Taking the 'true' branch" and the a variable is set to 21 (7 * 3).

The value of an if/else construct is null if the condition evaluates to false and no else branch is given.

While Loops

The while statement checks a condition and executes the loop body when the condition evaluates to true. This is repeated until the condition is no longer true.

Example:

var num = 5

while (num > 5) {
    log("Test")
    num -= 1
}

For Loops

The for statement can be used to iterate over arrays and dictionaries.

Example:

var list = [ "a", "b", "c" ]

for (item in list) {
  log("Item: " + item)
}

The loop body is evaluated once for each item in the array. The variable item is declared as a local variable just as if the var keyword had been used.

Iterating over dictionaries can be accomplished in a similar manner:

var dict = { a = 3, b = 7 }

for (key => value in dict) {
  log("Key: " + key + ", Value: " + value)
}

Types

All values have a static type. The typeof function can be used to determine the type of a value:

typeof(3) /* Returns an object which represents the type for numbers */

The following built-in types are available:

Type	Examples	Description
Number	3.7	A numerical value.
Boolean	true, false	A boolean value.
String	"hello"	A string.
Array	[ "a", "b" ]	An array.
Dictionary	{ a = 3 }	A dictionary.

Depending on which libraries are loaded additional types may become available. The icinga library implements a whole bunch of other types, e.g. Host, Service, CheckCommand, etc.

Each type has an associated type object which describes the type's semantics. These type objects are made available using global variables which match the type's name:

/* This logs 'true' */
log(typeof(3) == Number)

The type object's prototype property can be used to find out which methods a certain type supports:

/* This returns: ["find","len","lower","replace","split","substr","to_string","upper"] */
keys(String.prototype)

Reserved Keywords

These keywords are reserved and must not be used as constants or custom attributes.

object
template
include
include_recursive
library
null
true
false
const
var
this
use
apply
to
where
import
assign
ignore
function
return
for
if
else
in

You can escape reserved keywords using the @ character. The following example tries to set vars.include which references a reserved keyword and generates an error:

[2014-09-15 17:24:00 +0200] critical/config: Location:
/etc/icinga2/conf.d/hosts/localhost.conf(13):   vars.sla = "24x7"
/etc/icinga2/conf.d/hosts/localhost.conf(14):
/etc/icinga2/conf.d/hosts/localhost.conf(15):   vars.include = "some cmdb export field"
                                                     ^^^^^^^
/etc/icinga2/conf.d/hosts/localhost.conf(16): }
/etc/icinga2/conf.d/hosts/localhost.conf(17):

Config error: in /etc/icinga2/conf.d/hosts/localhost.conf: 15:8-15:14: syntax error, unexpected include (T_INCLUDE), expecting T_IDENTIFIER
[2014-09-15 17:24:00 +0200] critical/config: 1 errors, 0 warnings.

You can escape the include keyword by prefixing it with an additional @ character:

object Host "localhost" {
  import "generic-host"

  address = "127.0.0.1"
  address6 = "::1"

  vars.os = "Linux"
  vars.sla = "24x7"

  vars.@include = "some cmdb export field"
}

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Language Reference

Object Definition

Expressions

Numeric Literals

Duration Literals

String Literals

Multi-line String Literals

Boolean Literals

Null Value

Dictionary

Array

Operators

Function Calls

Assignments

Operator =

Operator +=

Operator -=

Operator *=

Operator /=

Indexer

Template Imports

Constants

Apply

Group Assign

Boolean Values

Comments

Includes

Recursive Includes

Library directive

Functions

Lambda Expressions

Abbreviated Lambda Syntax

Variable Scopes

Conditional Statements

While Loops

For Loops

Types

Reserved Keywords

26 KiB

Raw Blame History