mirror of https://github.com/Icinga/icinga2.git
45 lines
1.7 KiB
Markdown
45 lines
1.7 KiB
Markdown
## <a id="dependencies"></a> Dependencies
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Icinga 2 uses host and service [Dependency](#objecttype-dependency) objects either directly
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defined or as inline definition as `dependencies` dictionary. The `parent_host` and `parent_service`
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attributes are mandatory, `child_host` and `child_service` attributes are obsolete within
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inline definitions in an existing service object or service inline definition.
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A service can depend on a host, and vice versa. A service has an implicit dependency (parent)
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to its host. A host to host dependency acts implicit as host parent relation.
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When dependencies are calculated, not only the immediate parent is taken into
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account but all parents are inherited.
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A common scenario is the Icinga 2 server behind a router. Checking internet
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access by pinging the Google DNS server `google-dns` is a common method, but
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will fail in case the `dsl-router` host is down. Therefore the example below
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defines a host dependency which acts implicit as parent relation too.
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Furthermore the host may be reachable but ping probes are dropped by the
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router's firewall. In case the `dsl-router``ping4` service check fails, all
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further checks for the `ping4` service on host `google-dns` service should
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be suppressed. This is achieved by setting the `disable_checks` attribute to `true`.
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object Host "dsl-router" {
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vars.address = "192.168.1.1"
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}
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object Host "google-dns" {
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vars.address = "8.8.8.8"
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}
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apply Service "ping4" {
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import "generic-service"
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check_command = "ping4"
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assign where host.vars.address
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}
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apply Dependency "internet" {
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parent_host = "dsl-router"
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disable_checks = true
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assign where host.name != "dsl-router"
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}
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