RFC: Process Github issue_comment events to support adhoc task creati…

…on (#168)

README.md

@@ -61,3 +61,4 @@ See [mechanics](mechanics.md) for more detail.
 | RFC#163 | [ProjectId](rfcs/0163-project-id.md)                                                                                                                                                   |
 | RFC#165 | [Anonymous scopes](rfcs/0165-Anonymous-scopes.md)                                                                                                                                      |
 | RFC#166 | [Sign Public S3 URLs](rfcs/0166-Sign-public-S3-urls.md)                                                                                                                                |
+| RFC#168 | [Process Github issue_comment events to support adhoc task creation](rfcs/0168-Trigger-Tests-Based-on-PR-Comments.md)                                                                  |

rfcs/0168-Trigger-Tests-Based-on-PR-Comments.md

@@ -0,0 +1,37 @@
+# RFC 168 - Process Github issue_comment events to support adhoc task creation
+* Comments: [#168](https://github.com/taskcluster/taskcluster-rfcs/pull/168)
+* Proposed by: @bhearsum
+
+# Summary
+
+Listen, and render `.taskcluster.yml`, for Github `issue_comment` events.
+
+## Motivation
+
+Multiple use cases for triggering tasks in an adhoc manner on Pull Requests have come up recently. Most notably:
+* Triggering tasks for PRs opened by a non-collaborator
+* Triggering tasks that don't run by default (ie: because they're expensive)
+
+As Taskcluster is used increasingly for high-importance projects on Github (like Fenix), it's important that we're able to support these use cases.
+
+# Details
+
+`.taskcluster.yml` will be modified to support a new `allowComments` policy, which will support `collaborators` as a value. When set, collaborators to the repository may add a comment containing a string beginning with "/taskcluster ", which will cause Taskcluster-Github to render `.taskcluster.yml` with `tasks_for` set to `github-issue-comment`, and a new context variable `event.issue.comment` set to everything appearing after "/taskcluster " in the comment. For example, a comment of "/taskcluster run-tests" will set `event.comment` to `run-tests`. This will allow `.taskcluster.yml` implementers the flexibility to take different actions based on the comment. Some examples:
+* A comment of "/taskcluster run-tests" could trigger all Tasks
+* A comment of "/taskcluster run-test-foo" could trigger just the `foo` Task
+* A comment of "/taskcluster merge" could trigger a Task that merges the PR
+
+To support this, Taskcluster-Github will be modified to watch for [`issue_comment`](https://docs.github.com/en/developers/webhooks-and-events/webhook-events-and-payloads#issue_comment) events. When one is received, it will check if:
+* The `allowComments` policy is set to `collaborators` in the `.taskcluster.yml` on the default branch
+* The `sender` is a valid collaborator
+
+If the above is true, it will process the `.taskcluster.yml` as described above, and create any resulting Tasks.
+
+Because we will be listening for a new event, existing installations that want to make use of this feature will need to re-authorize the Taskcluster integration. New installations will get it by default upon install.
+
+This has been previously discussed in https://github.com/taskcluster/taskcluster-rfcs/issues/95 and https://github.com/taskcluster/taskcluster/issues/40.
+
+# Implementation
+
+* Tracking bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1715848
+* RRA (to be scheduled after RFC is Accepted)

rfcs/README.md

@@ -49,3 +49,4 @@
 | RFC#163 | [ProjectId](0163-project-id.md)                                                                                                                                                   |
 | RFC#165 | [Anonymous scopes](0165-Anonymous-scopes.md)                                                                                                                                      |
 | RFC#166 | [Sign Public S3 URLs](0166-Sign-public-S3-urls.md)                                                                                                                                |
+| RFC#168 | [Process Github issue_comment events to support adhoc task creation](0168-Trigger-Tests-Based-on-PR-Comments.md)                                                                  |