Parameters¶

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.

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

Push Information¶

base_repository: The repository from which to do an initial clone, utilizing any available caching.
head_repository: 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.
head_rev: The revision to check out; this can be a short revision string
head_ref: 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.
owner: Email address indicating the person who made the push. Note that this value may be forged and must not be relied on for authentication.
message: The commit message
pushlog_id: The ID from the hg.mozilla.org pushlog

Tree Information¶

project: Another name for what may otherwise be called tree or branch or repository. This is the unqualified name, such as mozilla-central or cedar.
level: 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.

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).

The decision task writes its task set to the target_tasks.json artifact, and this can be copied into parameters.target_tasks and parameters.target_tasks_method set to "from_parameters" for debugging with other mach taskgraph commands.

target_tasks_method: (optional) The method to use to determine the target task set. This is the suffix of one of the functions in tascluster/taskgraph/target_tasks.py. If omitted, all tasks are targeted.
target_tasks: (optional) The target set method from_parameters reads the target set, as a list of task labels, from this parameter.
optimize_target_tasks: (optional; default True) If true, then target tasks are eligible for optimization.