Action Specification ==================== This document specifies how actions exposed by the *decision task* are to be presented and triggered from Treeherder, or similar user interfaces. The *decision task* creates an artifact ``public/actions.json`` to be consumed by a user interface such as Treeherder. The ``public/actions.json`` file specifies actions that can be triggered such as: * Retrigger a task, * Retry specific test cases many times, * Obtain a loaner machine, * Back-fill missing tasks, * ... Through the ``public/actions.json`` file it is possible expose actions defined in-tree such that the actions can be conveniently triggered in Treeherder. This has two purposes: 1. Facilitate development of utility actions/tools in-tree, and, 2. Strongly decouple build/test configuration from Treeherder. For details on how define custom actions in-tree, refer to :doc:`the in-tree actions section `. This document merely specifies how ``actions.json`` shall be interpreted. Actions ------- The content of ``actions.json`` is a list of actions (and variables, to be described later). Each action has a ``kind`` describing how a user interface should trigger it. There is currently only one kind defined: ``task``. An action with ``kind: 'task'`` specifies a task that the user interface should create. That is, when the action is triggered, the user interface calls the Taskcluster API to create a new task, with the content of that task determined from ``actions.json``. The task created by the action may be useful in its own right (for example, running a test with additional debugging), or it may simplify trigger in-tree scripts that create new tasks. The latter form is called an *action task*, and is similar to a decision task. This allows in-tree scripts to execute complicated actions such as backfilling. Actions of the ``'task'`` *kind* **must** have a ``task`` property. This property specifies the task template to be parameterized and created in order to trigger the action. The template is parameterized using `JSON-e `_, with the following context entries available: ``taskGroupId`` the ``taskGroupId`` of task-group this is triggerd from, ``taskId`` the ``taskId`` of the selected task, ``null`` if no task is selected (this is the case if the action has ``context: []``), ``task`` the task definition of the selected task, ``null`` if no task is selected (this is the case if the action has ``context: []``), and, ``input`` the input matching the ``schema`` property, ``null`` if the action doesn't have a ``schema`` property. See "Action Input" below. ```` Any ```` defined in the ``variables`` property may also be referenced. See "Variables" below. The following **example** demonstrates how a task template can specify timestamps and dump input JSON into environment variables:: { "version": 1, "actions": [ { "kind": "task", "name": "thing", "title: "Do A Thing", "description": "Do something", "task": { "workerType": "my-worker", "payload": { "created": {"$fromNow": ""}, "deadline": {"$fromNow": "1 hour 15 minutes"}, "expiration": {"$fromNow": "14 days"}, "image": "my-docker-image", "env": { "TASKID_TRIGGERED_FOR": "${taskId}", "INPUT_JSON": {"$json": {"$eval": "input"}} }, ... }, ... } } ], "variables: {}, } MetaData ........ Each action entry must define a ``name``, ``title`` and ``description``. furthermore, the list of actions should be sorted by the order in which actions should appear in a menu. The ``name`` is used by user interfaces to identify the action. For example, a retrigger button might look for an action with `name = "retrigger"`. Action names must be unique for a given task, or for a taskgroup, but the same name may be used for actions applying to disjoint sets of tasks. For example, it may be helpful to define different "retrigger" actions for build tasks `[{jobKind: 'build'}]` and test tasks `[{jobKind: 'test'}]`, and in this case only one such action would apply to any given task. The ``title`` is a human readable string intended to be used as label on the button, link or menu entry that triggers the action. This should be short and concise. Ideally, you'll want to avoid duplicates. The ``description`` property contains a human readable string describing the action, such as what it does, how it does it, what it is useful for. This string is to be render as **markdown**, allowing for bullet points, links and other simple formatting to explain what the action does. Action Context .............. Few actions are relevant in all contexts. For this reason each action specifies a ``context`` property. This property specifies when an action is relevant. Actions *relevant* for a task should be displayed in a context menu for the given task. Similarly actions *not relevant* for a given task should not be displayed in the context menu for the given task. As a special case we say that actions for which *no relevant* contexts can exist, are *relevant* for the task-group. This could for example be an action to create tasks that was optimized away. The ``context`` property is specified as a list of *tag-sets*. A *tag-set* is a set of key-value pairs. A task is said to *match* a *tag-set* if ``task.tags`` is a super-set of the *tag-set*. An action is said to be *relevant* for a given task, if ``task.tags`` *match* one of the *tag-sets* given in the ``context`` property for the action. Naturally, it follows that an action with an empty list of *tag-sets* in its ``context`` property cannot possibly be *relevant* for any task. Hence, by previously declared special case such an action is *relevant* for the task-group. **Examples**:: // Example task definitions (everything but tags eclipsed) TaskA = {..., tags: {kind: 'test', platform: 'linux'}} TaskB = {..., tags: {kind: 'test', platform: 'windows'}} TaskC = {..., tags: {kind: 'build', platform: 'linux'}} Action1 = {..., context: [{kind: 'test'}]} // Action1 is relevant to: TaskA, TaskB Action2 = {..., context: [{kind: 'test', platform: 'linux'}]} // Action2 is relevant to: TaskA Action3 = {..., context: [{platform: 'linux'}]} // Action3 is relevant to: TaskA, TaskC Action4 = {..., context: [{kind: 'test'}, {kind: 'build'}]} // Action4 is relevant to: TaskA, TaskB, TaskC Action5 = {..., context: [{}]} // Action5 is relevant to: TaskA, TaskB, TaskC (all tasks in fact) Action6 = {..., context: []} // Action6 is relevant to the task-group Action Input ............ An action can take JSON input, the input format accepted by an action is specified using a `JSON schema `_. This schema is specified with by the action's ``schema`` property. For example:: { "version": 1, "actions": [ { "kind": "task", "name": "thing", "title: "Do A Thing", "description": "Do something", "schema": { "description": "The thing to do", "title": "Thing", "default": "something", "type": "string" "maxLength": 255 }, "task": { "payload": { "env": { "INPUT_JSON": {"$json": {"$eval": "input"}} }, ... }, ... } } ], "variables: {}, } User interfaces for triggering actions, like Treeherder, are expected to provide JSON input that satisfies this schema. These interfaces are also expected to validate the input against the schema before attempting to trigger the action. It is perfectly legal to reference external schemas using constructs like ``{"$ref": "https://example.com/my-schema.json"}``, in this case it however strongly recommended that the external resource is available over HTTPS and allows CORS requests from any source. When writing schemas it is strongly encouraged that the JSON schema ``description`` properties are used to provide detailed descriptions. It is assumed that consumers will render these ``description`` properties as markdown. Variables --------- The ``public/actions.json`` artifact has a ``variables`` property that is a mapping from variable names to JSON values to be used as constants. These variables can be referenced from task templates, but beware that they may overshadow builtin variables. This is mainly useful to deduplicate commonly used values, in order to reduce template size. This feature does not introduce further expressiveness. Formal Specification -------------------- The following is the JSON schema for ``actions.json``. .. literalinclude:: actions-schema.yml :language: YAML