Task-graph generation takes a collection of parameters as input, in the form of a JSON or YAML file.

During decision-task processing, some of these parameters are supplied on the command line or by environment variables. The decision task helpfully produces a full parameters file as one of its output artifacts. The other mach taskgraph commands can take this file as input. This can be very helpful when working on a change to the task graph.

When experimenting with local runs of the task-graph generation, it is always best to find a recent decision task’s parameters.yml file, and modify that file if necessary, rather than starting from scratch. This ensures you have a complete set of parameters.

The properties of the parameters object are described here, divided roughly by topic.

Push Information

The repository from which to do an initial clone, utilizing any available caching.
The repository containing the changeset to be built. This may differ from base_repository in cases where base_repository is likely to be cached and only a few additional commits are needed from head_repository.
The revision to check out; this can be a short revision string
For Mercurial repositories, this is the same as head_rev. For git repositories, which do not allow pulling explicit revisions, this gives the symbolic ref containing head_rev that should be pulled from head_repository.
Include nightly builds and tests in the graph.
Email address indicating the person who made the push. Note that this value may be forged and must not be relied on for authentication.
The commit message
The ID from the pushlog
The timestamp of the push to the repository that triggered this decision task. Expressed as an integer seconds since the UNIX epoch.
The timestamp of the build date. Defaults to pushdate and falls back to present time of taskgraph invocation. Expressed as an integer seconds since the UNIX epoch.
A formatted timestamp of build_date. Expressed as a string with the following format: %Y%m%d%H%M%S

Tree Information

Another name for what may otherwise be called tree or branch or repository. This is the unqualified name, such as mozilla-central or cedar.
The SCM level associated with this tree. This dictates the names of resources used in the generated tasks, and those tasks will fail if it is incorrect.

Try Configuration

The mode in which a try push is operating. This can be one of "try_task_config", "try_option_syntax", or None meaning no try input was provided.
The arguments given as try syntax (as a dictionary), or None if try_mode is not try_option_syntax.
The contents of the try_task_config.json file, or None if try_mode is not try_task_config.

Target Set

The “target set” is the set of task labels which must be included in a task graph. The task graph generation process will include any tasks required by those in the target set, recursively. In a decision task, this set can be specified programmatically using one of a variety of methods (e.g., parsing try syntax or reading a project-specific configuration file).

List of filter functions (from taskcluster/taskgraph/ to apply. This is usually defined internally, as filters are typically global.
The method to use to determine the target task set. This is the suffix of one of the functions in taskcluster/taskgraph/
If true, then nightly tasks are eligible for optimization.
History of recent releases by platform and locale, used when generating partial updates for nightly releases. Suitable contents can be generated with mach release-history, which will print to the console by default.


If true, then target tasks are eligible for optimization.
Specify tasks to not optimize out of the graph. This is a list of labels. Any tasks in the graph matching one of the labels will not be optimized out of the graph.
Specify tasks to optimize out of the graph. This is a dictionary of label to taskId. Any tasks in the graph matching one of the labels will use the previously-run taskId rather than submitting a new task.

Release Promotion

Specify the release promotion build number.
Specify the version for release tasks.
Specify the application version for release tasks. For releases, this is often a less specific version number than version.
Specify the next version for version bump tasks.
The type of release being promoted. One of “beta”, “devedition”, “esr”, “rc”, or “release”.
The time and date when a release is scheduled to live. This value is passed to Balrog.
Boolean which controls repacking vanilla Firefox builds for partners.
List of partners to repack. A null value defaults to all.
Configuration for partner repacks.
The build number for partner repacks. We sometimes have multiple partner build numbers per release build number; this parameter lets us bump them independently. Defaults to 1.
Boolean which controls repacking vanilla Firefox builds into EME-free builds.

Comm Push Information

These parameters correspond to the repository and revision of the comm-central repository to checkout. Their meaning is the same as the corresponding parameters for the gecko repository above. They are optional, but if any of them are specified, they must all be specified.

comm_base_repository comm_head_repository comm_head_rev comm_head_ref