Release Promotion Action

The release promotion action is how Releng triggers release promotion taskgraphs. The one action covers all release promotion needs: different flavors allow for us to trigger the different release promotion phases for each product. The input schema and release promotion flavors are defined in the release promotion action.

The snowman model

The release promotion action allows us to chain multiple taskgraphs (aka graphs, aka task groups) together. Essentially, we’re using optimization logic to replace task labels in the current taskgraph with task IDs from the previous taskgraph(s).

This is the snowman model. If you request the body of the snowman and point at the base, we only create the middle section of the snowman. If you request the body of the snowman and don’t point it at the base, we build the first base and body of the snowman from scratch.

For example, let’s generate a task t2 that depends on t1. Let’s call our new taskgraph G:


Task t2 will wait on task t1 to finish, and downloads some artifacts from task t1.

Now let’s specify task group G1 and G2 as previous task group IDs. If task t1 is in one of them, t2 will depend on that task, rather than spawning a new t1 in task group G:

G1        G2        G
|         |         |
t1        t1        |
            \______ |


G1        G2        G
|         |         |
t1        t0        |
  \________________ |

For a more real-world example:


If we point the promote task group G at the on-push build task group G1, the l10n-repack job will depend on the previously finished build and build-signing tasks:

   G1            G
   |             |
 build           |
   |             |
signing          |

We can also explicitly exclude certain tasks from being optimized out. We currently do this by specifying rebuild_kinds in the action; these are kinds that we want to explicitly rebuild in the current task group, even if they existed in previous task groups. We also allow for specifying a list of do_not_optimize labels, which would be more verbose and specific than specifying kinds to rebuild.

Release promotion action mechanics

There are a number of inputs defined in the release promotion action. Among these are the previous_graph_ids, which is an ordered list of taskGroupIds of the task groups that we want to build our task group, off of. In the snowman model, these define the already-built portions of the snowman.

The action downloads the parameters.yml from the initial previous_graph_id, which matches the decision- or action- taskId. (See Release promotion action taskId and taskGroupId.) This is most likely the decision task of the revision to promote, which is generally the same revision the release promotion action is run against.


If the parameters have been changed since the build happened, and we explicitly want the new parameters for the release promotion action task, the first previous_graph_id should be the new revision’s decision task. Then the build and other previous action task group IDs can follow, so we’re still replacing the task labels with the task IDs from the original revision.

The action then downloads the various label-to-taskid.json artifacts from each previous task group, and builds an existing_tasks parameter of which labels to replace with which task IDs. Each successive update to this dictionary overwrites existing keys with new task IDs, so the rightmost task group with a given label takes precedence. Any labels that match the do_not_optimize list or that belong to tasks in the rebuild_kinds list are excluded from the existing_tasks parameter.

Once all that happens, and we’ve gotten our configuration from the original parameters and our action config and inputs, we run the decision task function with our custom parameters. The optimization phase replaces any existing_tasks with the task IDs we’ve built from the previous task groups.

Release Promotion Flavors

For the most part, release promotion flavors match the pattern phase_product, e.g. promote_fennec, push_devedition, or ship_firefox.

We’ve added _rc suffix flavors, to deal with special RC behavior around rolling out updates using a different rate or channel.

We are planning on adding _partners suffix flavors, to allow for creating partner repacks off-cycle.

The various flavors are defined in the release promotion action.

Triggering the release promotion action via Treeherder

Currently, we’re able to trigger this action via Treeherder; we sometimes use this method for testing purposes. This is powerful, because we can modify the inputs directly, but is less production friendly, because it requires us to enter the inputs manually. At some point we may disable the ability to trigger the action via Treeherder.

This requires being signed in with the right scopes. On Release Promotion Projects, there’s a dropdown in the top right of a given revision. Choose Custom Push Action, then Release Promotion. The inputs are specifiable as raw yaml on the left hand column.

Triggering the release promotion action via releaserunner3

Releaserunner3 is our current method of triggering the release promotion action from Ship It in production. Examples of how to run this are in the releasewarrior docs.

To deal with the above previous_graph_ids logic, we allow for a decision_task_id in As of 2018-03-14, this script assumes we want to download parameters.yml from the same decision task that we get actions.json from. At some point, we’d like the call to happen automatically once we push a button on Ship It.

The action task that’s generated from actions.json matches the .taskcluster.yml template. This is important; Chain of Trust (v2) requires that the task definition be reproducible from .taskcluster.yml.

Release promotion action taskId and taskGroupId

The taskGroupId of a release promotion action task will be the same as the taskId of the decision task.

The taskGroupId of a release promotion task group will be the same as the taskId of the release promotion action task.


  • for a given push, the decision taskId D will create the taskGroupId D
  • we create a release promotion action task with the taskId A. The A task will be part of the D task group, but will spawn a task group with the taskGroupId A.

Another way of looking at it:

  • If you’re looking at a task t1 in the action taskGroup, t1’s taskGroupId is the action task’s taskId. (In the above example, this would be A.)
  • Then if you look at the action task’s taskGroupId, that’s the original decision task’s taskId. (In the above example, this would be D.)

Testing and developing the release promotion action

To test the release promotion, action, we can use ./mach taskgraph test-action-callback to debug.

The full command for a promote_fennec test might look like:

./mach taskgraph test-action-callback \
    --task-group-id LR-xH1ViTTi2jrI-N1Mf2A \
    --input /src/gecko/params/promote_fennec.yml \
    -p /src/gecko/params/maple-promote-fennec.yml \
    release_promotion_action > ../promote.json

The input file (in the above example, that would be /src/gecko/params/promote_fennec.yml), contains the action inputs. The input schema is defined in the release promotion action. Previous example inputs are embedded in previous promotion task group action task definitions (task.extra.action.input).

The parameters.yml file is downloadable from a previous decision or action task.