More fixes from review

- Replaced the TODO notes in `releases.md` with text
- Renamed the taskcluster `release` attribute to `release-type`

docs/howtos/releases.md

@@ -12,11 +12,15 @@ Nightly builds are automatically generated using a taskcluster cron task.
 
 ## Release builds
 
-Release builds are generated from the `release-vXXX` branches.  Whenever a commit is pushed there,
-we build all artifacts needed for the release.  Once we're ready to publish the release, we run the
-taskcluster release promotion action which signs and publishes the artifacts.
+Release builds are generated from the `release-vXXX` branches and published with the
+`release-promotion` action, which has several phases:
 
-TODO: explain release-promotion more.
+- Whenever a commit is pushed to a release branch, we build candidate artifacts. These artifacts are
+  shippable -- if we decide that the release is ready, they just need to be copied to the correct
+  location.
+- The `push` phase of `release-promotion` copies the candidate to a staging location where they can
+  be tested.
+- The `ship` phase of `release-promotion` copies the candidate to their final, published, location.
 
 ## What to do at the end of a nightly cycle
 
@@ -38,11 +42,9 @@ index 8cd923873..6482018e0 100644
  groupId: org.mozilla.appservices
 ```
 
- * Create a PR on `main` that starts a new CHANGELOG haeder.
+ * Create a PR on `main` that starts a new CHANGELOG header.
 
-3. Trigger release-promotion once the PRs are approved, merged, and CI has completed
-
- * TODO: explain how to do this
+3. Ask releng to trigger release-promotion once the PRs are approved, merged, and CI has completed
 
 4. Tag the release with `automation/tag-release.py [major-version-number]`
 

taskcluster/app_services_taskgraph/__init__.py

@@ -33,7 +33,7 @@ def register(graph_config):
         # preview build for a particular application-services branch.
         'preview-build': str,
         # Release type.  We set this to "release" for non-nightly builds, it defaults to "nightly".
-        'release': Optional(str),
+        'release-type': Optional(str),
     })
 
 def _import_modules(modules):

taskcluster/app_services_taskgraph/target_tasks.py

@@ -22,7 +22,7 @@ def target_tasks_all(full_task_graph, parameters, graph_config):
     def filter(task):
         return (filter_for_tasks_for(task, parameters) 
                 and task.attributes.get("run-on-pr-type", "all") in ("full-ci", "all")
-                and task.attributes.get('release') != 'release-only')
+                and task.attributes.get('release-type') != 'release-only')
 
     return [l for l, task in full_task_graph.tasks.items() if filter(task)]
 
@@ -33,6 +33,6 @@ def target_tasks_default(full_task_graph, parameters, graph_config):
     def filter(task):
         return (filter_for_tasks_for(task, parameters)
                 and task.attributes.get("run-on-pr-type", "all") in ("normal-ci", "all")
-                and task.attributes.get('release') != 'release-only')
+                and task.attributes.get('release-type') != 'release-only')
 
     return [l for l, task in full_task_graph.tasks.items() if filter(task)]

taskcluster/ci/build-summary/kind.yml

@@ -20,7 +20,7 @@ transforms:
 tasks:
   deps_complete:
     attributes:
-      release: release-only
+      release-type: release-only
     label: "Build summary task"
     description: "Summary task for the nightly/release builds that reports failures."
     alerts:

taskcluster/ci/release-publish/kind.yml

@@ -23,7 +23,7 @@ transforms:
 tasks:
   release_publish:
     attributes:
-      release: release-only
+      release-type: release-only
     label: "Build publish task"
     description: "Publish build artifacts"
     worker-type: b-linux

taskcluster/test/params/release-branch-push.yml

@@ -19,4 +19,4 @@ pushlog_id: '0'
 repository_type: git
 target_tasks_method: release
 tasks_for: github-push
-release: "release"
+release-type: "release"