# Periodic Taskgraphs

The cron functionality allows in-tree scheduling of task graphs that run
periodically, instead of on a push.

## Cron.yml

In the root of the Comm directory, you will find `.cron.yml`. This defines
the periodic tasks ("cron jobs") that run for Thunderbird.

See [the Firefox CI cron documentation](https://firefox-source-docs.mozilla.org/taskcluster/cron.html)
for a description of `.cron.yml`.

## Disabling Cron Jobs

Sometimes due to build bustage, it's desirable to disable the automatic
Thunderbird Daily builds. The best way to do this is to change `.cron.yml`
so that the jobs are never scheduled. This is done by changing `when` to an
empty list.

The Daily build is started by the `nightly-desktop` job. Additionally, there
is a `searchfox-index` job that should be disabled as well when disabling
Dailies.

For both of these, comment out the `when` line that sets a time and uncomment
the next line which sets an empty list.

```{code-block} yaml
:linenos:
:emphasize-lines: 8,9

  - name: nightly-desktop
    job:
        type: decision-task
        treeherder-symbol: Nd
        target-tasks-method: nightly_desktop
    run-on-projects:
        - comm-central
    when: [{hour: 11, minute: 0}]
    # when: []
```

## L10n-bump Cron Job

`l10n-bump` runs daily on comm-beta. For RC week (week 4) it needs to be
disabled by pushing a change directly to `comm-beta` setting `when` to
an empty list as above.

**Do not make the change on comm-central first.** `l10n-bump` will be
re-enabled by merge day activities automatically.