2020-03-25 16:57:53 +00:00
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---
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layout: docs
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page_title: lifecycle Stanza - Job Specification
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2020-03-25 17:30:44 +00:00
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sidebar_title: lifecycle <sup>0.11 Beta</sup>
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2020-03-25 16:57:53 +00:00
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description: The "lifecycle" stanza configures when a task is run within the lifecycle of a task group
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---
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2020-03-25 17:30:44 +00:00
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# `lifecycle` Stanza <sup>0.11 Beta</sup>
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2020-03-25 16:57:53 +00:00
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<Placement groups={['job', 'group', 'task', 'lifecycle']} />
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The `lifecycle` stanza configures when a task is run within the lifecycle of a task group.
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Main tasks are tasks that do not have a `lifecycle` stanza.
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Lifecycle task hooks are run in relation to the main tasks.
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Tasks can be run as Prestart Hooks, which ensures the prestart task is run before the main tasks are run.
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Tasks can be run with an additional parameter to indicate that they are sidecars, which ensures
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that they are running over the duration of the whole task group. This will allow you to run
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a long-lived task in a task group for a batch job. The absence of the sidecar flag
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indicates that the task is ephemeral and the task will not be restarted if it completes successfully.
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This allows you to run an ephemeral prestart task in a task group for a service job,
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which can serve as initialization that occurs before the main services are started.
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```hcl
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job "docs" {
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group "example" {
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task "init" {
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lifecycle {
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hook = "prestart"
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}
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...
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}
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task "logging" {
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lifecycle {
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hook = "prestart"
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sidecar = true
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}
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...
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}
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task "main" {
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...
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}
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}
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}
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```
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## `lifecycle` Parameters
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- `hook` `(string: "prestart")` - Specifies when a task should be run within
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the lifecycle of a group. Currently only Prestart Hooks are supported.
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- `sidecar` `(bool: false)` - Controls whether or not a task is ephemeral or long-lived
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within the task group. If a lifecycle task is ephemeral (`sidecar = false`),
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the task will not be restarted after it completes successfully.
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If a lifecycle task is long-lived (`sidecar = true`) and it terminates, it will be
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restarted as long as the task group is running in its allocation.
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