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Juanadelacuesta authored Nov 8, 2024
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61 changes: 61 additions & 0 deletions website/content/docs/job-specification/parameterized.mdx
Original file line number Diff line number Diff line change
Expand Up @@ -152,9 +152,70 @@ job "email-blast" {
}
```

### Use periodic with parameterized

Nomad uses an internal hierarchy when scheduling a job that is both `parameterized` and [`periodic`][periodic].

```plaintext
parameterized => periodic => batch
```

Nomad processes a periodic with parameterized job in the following order:

1. Nomad does not dispatch a periodic job with null parameters in the periodic configuration. This forces the parameterized job to take precedence over the periodic job.
2. After Nomad dispatches the parameterized job and gives it parameters, Nomad uses the periodic configuration.
3. Nomad dispatches new jobs according to the periodic configuration that uses thee parameters from the triggering parameterized job.

In this example, the periodic job does not trigger any new jobs
until the operator dispatches the parameterized job at least once. After that, the
dispatched child periodically triggers more children with the given parameters.

```hcl
periodic {
crons = [
"*/40 * * * * * *"
]
}
parameterized {
payload = "required"
meta_required = ["dispatcher_email"]
meta_optional = ["pager_email"]
}
```



There are three columns plus comments in this example output, which is for the preceding periodic, parameterized example job. Scroll to the last column to review the comments.

```
$ nomad job status
ID Type Submit Date
sync batch/periodic/parameterized 2024-11-07T10:43:30+01:00 // Original submitted job
sync/dispatch-1730972650-247c6e97 batch/periodic 2024-11-07T10:44:10+01:00 // First dispatched job with parameters A
sync/dispatch-1730972650-247c6e97/periodic-1730972680 batch 2024-11-07T10:44:40+01:00 // Cron job with parameters A
sync/dispatch-1730972650-247c6e97/periodic-1730972860 batch 2024-11-07T10:47:40+01:00 // Cron job with parameters A
sync/dispatch-1730972760-f79a96e1 batch/periodic 2024-11-07T10:46:00+01:00 // Second dispatched job with parameters B
sync/dispatch-1730972760-f79a96e1/periodic-1730972800 batch 2024-11-07T10:46:40+01:00 // Cron job with parameters B
sync/dispatch-1730972760-f79a96e1/periodic-1730972860 batch 2024-11-07T10:47:40+01:00 // Cron job with parameters B
```
The output illustrates the following:

1. The `sync` job is the parameterized and periodic job. However, Nomad doesn't run the periodic job until you submit with the required parameters.
2. The `sync/dispatch-1730972650-247c6e97` job contains parameters and triggers the batch jobs, named `sync/dispatch-1730972650-247c6e97/periodic-1730972680` and `sync/dispatch-1730972650-247c6e97/periodic-1730972860`.
3. The `sync/dispatch-1730972760-f79a96e1` job assigns new parameters and triggers new batch jobs that use those parameters.

If you need to force the periodic job, force the the corresponding parameterized job.

This example forces the first dispatched job with parameters A from the preceding example.

```
$ nomad job periodic force sync/dispatch-1730972650-247c6e97
```

[batch-type]: /nomad/docs/job-specification/job#type 'Batch scheduler type'
[dispatch command]: /nomad/docs/commands/job/dispatch 'Nomad Job Dispatch Command'
[resources]: /nomad/docs/job-specification/resources 'Nomad resources Job Specification'
[interpolation]: /nomad/docs/runtime/interpolation 'Nomad Runtime Interpolation'
[dispatch_payload]: /nomad/docs/job-specification/dispatch_payload 'Nomad dispatch_payload Job Specification'
[multiregion]: /nomad/docs/job-specification/multiregion#parameterized-dispatch
[periodic]: /nomad/docs/job-specification/periodic
3 changes: 3 additions & 0 deletions website/content/docs/job-specification/periodic.mdx
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Expand Up @@ -32,6 +32,8 @@ consistent evaluation when Nomad spans multiple time zones.
- The job's [scheduler type][batch-type] must be `batch` or `sysbatch`.
- A job can not be updated to be periodically. Thus, to transition an existing job to be periodic, you must first run `nomad stop -purge «job name»`. This is expected behavior and is to ensure that this change has been intentionally made by an operator.

Refer to the [parameterized] documentation for how to use parameters with a periodic job.

## `periodic` Parameters

- `cron` (_deprecated_: Replaced by `crons` in 1.6.2) `(string)` - Specifies a cron expression configuring the
Expand Down Expand Up @@ -116,3 +118,4 @@ configuring time zones for periodic jobs.
[cron]: https://github.com/hashicorp/cronexpr#implementation 'List of cron expressions'
[dst]: #daylight-saving-time
[multiregion]: /nomad/docs/job-specification/multiregion#periodic-time-zones
[parameterized]: /nomad/docs/job-specification/parameterized#use-periodic-with-parameterized

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