Add a workflow which automatically adds backport tags based upon chan…

…gelogs (#2454)

##### SUMMARY

As has been recently noticed, we're being inconsistent with backporting things.

Based on the keys from the changelog fragments this action would perform the following actions:

- On "push" or applying the `mergeit` label
  -  If a PR contains **non-backportable** changes (`major_changes`, `breaking_changes`, `removed_features`) the `do_not_backport` label will be applied.  These change types are assumed to require a "major" release, and as such shouldn't be backported into a currently "stable" release.  At the same time it will remove any previously applied `backport-*` labels.
- When the "mergeit" label is applied:
  - If a PR contains changes that only need a **minor release** (minor_changes, deprecated_features) the `backport-9` label will be applied.
  - If a PR contains changes that only need a **patch release**, such as security/bug fixes (bugfixes, security_fixes), then `backport-8` and `backport-9` labels will both be applied.

##### ISSUE TYPE

- Feature Pull Request

##### COMPONENT NAME

.github/workflows

##### ADDITIONAL INFORMATION

.github/workflows/backports.yml

@@ -0,0 +1,22 @@
+---
+name: mergeit-backport
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+on:
+  pull_request:
+    types:
+      - labeled
+      - opened
+      - synchronize
+    branches:
+      - main
+
+jobs:
+  changelog-labeller:
+    uses: ansible-network/github_actions/.github/workflows/backport-labeller.yml@main
+    with:
+      label_minor_release: backport-9
+      label_bugfix_release: backport-8

docs/docsite/rst/collection_release.rst

@@ -91,12 +91,6 @@ Ensure that your local copy of the ``main`` branch is up to date and contains al
 Preparing a new stable branch
 -----------------------------
 
-.. warning::
-  Zuul will need updating here too.
-
-  As part of the next release cycle please add an entry here about configuring the Zuul sanity jobs
-  for the new stable-6 branch.
-
 Create and push a new ``stable-<major-version>`` branch (for example ``stable-6`` for release
 ``6.0.0``):
 
@@ -108,6 +102,14 @@ Create and push a new ``stable-<major-version>`` branch (for example ``stable-6`
   git checkout -b stable-6
   git push --set-upstream origin stable-6
 
+Create a new label ``backport-<major-version>`` (for example ``backport-6`` for release ``6.0.0``).
+This can either be done through the `GitHub UI <https://github.com/ansible-collections/amazon.aws/labels>`_
+or using the GH CLI if you have it installed and configured:
+
+.. code-block:: bash
+
+  gh label create backport-6 -c FFAA22 --description "PR should be backported to the stable-6 branch" -R ansible-collections/amazon.aws
+
 Create a pull request against the new branch updating any documentation links from ``main`` to the
 new ``stable-<major-version>`` branch.
 
@@ -121,18 +123,40 @@ Now that our new major release has been branched, we update the ``main`` branch
 configured as the pre-release development version for the **next** release (for example
 ``7.0.0-dev0`` if you're preparing ``6.0.0``).
 
+Create a pull request against the ``main`` branch that updates the
+`backport-labeller workflow <https://github.com/ansible-collections/amazon.aws/tree/main/.github/workflows/backports.yml>`_
+so that non-breaking changes will automatically be backported to the new branch:
+
+.. code-block:: yaml
+
+  ---
+  name: mergeit-backport
+
+  ...
+
+  jobs:
+    changelog-labeller:
+      uses: ansible-network/github_actions/.github/workflows/backport-labeller.yml@main
+      with:
+        label_minor_release: backport-6
+        label_bugfix_release: backport-5
+
+
 Create a pull request against the ``main`` branch updating the
 `galaxy.yml <https://github.com/ansible-collections/amazon.aws/blob/main/galaxy.yml>`_ version
 information and the  `plugins/module_utils/common.py
 <https://github.com/ansible-collections/amazon.aws/blob/main/plugins/module_utils/common.py>`_
 version information to a ``dev0`` prerelease of the next major release.  This may result in deprecation
 errors from the sanity tests.  Create issues and add entries to the relevant
 `sanity test ignore files <https://github.com/ansible-collections/amazon.aws/tree/main/tests/sanity>`_.
-(including a link to the issue)
+(including a link to the issue).
 
 For an example pull request see
 `ansible-collections/amazon.aws#1108 <https://github.com/ansible-collections/amazon.aws/pull/1108>`_
 
+(In theory both steps can be done with a single PR.  However, the bot performing our automatic
+merges will refuse to merge PRs which make changes to the contents of .github.  Splitting the PRs up
+reduces the scope of the manually merged PR.)
 
 Next steps
 ----------