update release process to support multiple version

.github/actions/release-branches/action.yml

@@ -0,0 +1,25 @@
+name: 'Release branches'
+description: 'Determine branches for release & backport'
+inputs:
+  major_version:
+    description: 'The version as extracted from the package.json file'
+    required: true
+  latest_tag:
+    description: 'The most recent tag published to the repository'
+    required: true
+outputs:
+  backport_source_branch:
+    description: "The release branch for the given tag"
+    value: ${{ steps.branches.outputs.backport_source_branch }}
+  backport_target_branches:
+    description: "JSON encoded list of branches to target with backports"
+    value: ${{ steps.branches.outputs.backport_target_branches }}
+runs:
+  using: "composite"
+  steps:
+    - id: branches
+      run: |
+        python ${{ github.action_path }}/release-branches.py \
+            --major-version ${{ inputs.major_version }} \
+            --latest-tag ${{ inputs.latest_tag }}
+      shell: bash

.github/actions/release-branches/release-branches.py

@@ -0,0 +1,57 @@
+import argparse
+import os, json
+import subprocess
+
+# Name of the remote
+ORIGIN = 'origin'
+
+OLDEST_SUPPORTED_MAJOR_VERSION = 2
+
+# Runs git with the given args and returns the stdout.
+# Raises an error if git does not exit successfully (unless passed
+# allow_non_zero_exit_code=True).
+def run_git(*args, allow_non_zero_exit_code=False):
+  cmd = ['git', *args]
+  p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+  if not allow_non_zero_exit_code and p.returncode != 0:
+    raise Exception(f'Call to {" ".join(cmd)} exited with code {p.returncode} stderr: {p.stderr.decode("ascii")}.')
+  return p.stdout.decode('ascii')
+
+def main():
+
+  parser = argparse.ArgumentParser()
+  parser.add_argument("--major-version", required=True, type=str, help="The major version of the release")
+  parser.add_argument("--latest-tag", required=True, type=str, help="The most recent tag published to the repository")
+  args = parser.parse_args()
+
+  major_version = args.major_version
+  latest_tag = args.latest_tag
+
+  print("major_version: " + major_version)
+  print("latest_tag: " + latest_tag)
+
+  # If this is a primary release, we backport to all supported branches,
+  # so we check whether the major_version taken from the package.json
+  # is greater than or equal to the latest tag pulled from the repo.
+  # For example...
+  #     'v1' >= 'v2' is False # we're operating from an older release branch and should not backport
+  #     'v2' >= 'v2' is True  # the normal case where we're updating the current version
+  #     'v3' >= 'v2' is True  # in this case we are making the first release of a new major version
+  consider_backports = ( major_version >= latest_tag.split(".")[0] )
+
+  with open(os.environ["GITHUB_OUTPUT"], "a") as f:
+
+    f.write(f"backport_source_branch=releases/{major_version}\n")
+
+    backport_target_branches = []
+
+    if consider_backports:
+      for i in range(int(major_version.strip("v"))-1, 0, -1):
+        branch_name = f"releases/v{i}"
+        if i >= OLDEST_SUPPORTED_MAJOR_VERSION:
+          backport_target_branches.append(branch_name)
+
+    f.write("backport_target_branches="+json.dumps(backport_target_branches)+"\n")
+
+if __name__ == "__main__":
+  main()

.github/actions/release-initialise/action.yml

@@ -0,0 +1,33 @@
+name: 'Prepare release job'
+description: 'Executed preparatory steps before update a release branch'
+
+runs:
+  using: "composite"
+  steps:
+
+    - name: Dump environment
+      run: env
+      shell: bash
+
+    - name: Dump GitHub context
+      env:
+        GITHUB_CONTEXT: '${{ toJson(github) }}'
+      run: echo "$GITHUB_CONTEXT"
+      shell: bash
+
+    - name: Set up Python
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.8
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install PyGithub==1.55 requests
+      shell: bash
+
+    - name: Update git config
+      run: |
+        git config --global user.email "41898282+github-actions[bot]@users.noreply.github.com"
+        git config --global user.name "github-actions[bot]"
+      shell: bash