# Task Transforms

:::{note}
These transforms are currently duplicated by standalone Taskgraph
and will likely be refactored / removed at a later date.
:::

Every kind needs to create tasks, and all of those tasks have some things in
common. They all run on one of a small set of worker implementations, each
with their own idiosyncrasies. And they all report to TreeHerder in a similar
way.

The transforms in `taskcluster/gecko_taskgraph/transforms/task.py` implement
this common functionality. They expect a "task description", and produce a
task definition. The schema for a task description is defined at the top of
`task.py`, with copious comments. Go forth and read it now!

In general, the task-description transforms handle functionality that is common
to all Gecko tasks. While the schema is the definitive reference, the
functionality includes:

- TreeHerder metadata
- Build index routes
- Information about the projects on which this task should run
- Optimizations
- Defaults for `expires-after` and and `deadline-after`, based on project
- Worker configuration

The parts of the task description that are specific to a worker implementation
are isolated in a `task_description['worker']` object which has an
`implementation` property naming the worker implementation. Each worker
implementation has its own section of the schema describing the fields it
expects. Thus the transforms that produce a task description must be aware of
the worker implementation to be used, but need not be aware of the details of
its payload format.

The `task.py` file also contains a dictionary mapping treeherder groups to
group names using an internal list of group names. Feel free to add additional
groups to this list as necessary.
