ci: Create GitHub Release automatically

Add a GitHub job to create the GitHub Release automatically when
a version is tagged. Also use the GitHub feature to create the CHANGELOG
automatically. When creating the GitHub release the contents of the file
RELEASE_NOTES.md will be used as release notes, so it should only
contain an explanation on the release main changes and be user-facing.

Also add the release notes for the current release.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

.github/workflows/ci.yaml

@@ -69,20 +69,67 @@ jobs:
           path: dist/
           if-no-files-found: error
 
-  publish-to-pypi:
+  create-github-release:
     needs: ["test", "build-dist"]
-    # Publish only on tags creation
+    # Create a release only on tags creation
     if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
+    permissions:
+      # We need write permissions on contents to create GitHub releases and on
+      # discussions to create the release announcement in the discussion forums
+      contents: write
+      discussions: write
+    runs-on: ubuntu-20.04
+    steps:
+      - name: Download dist files
+        uses: actions/download-artifact@v3
+        with:
+          name: frequenz-channels-python-dist
+          path: dist
+
+      - name: Download RELEASE_NOTES.md
+        run: |
+          set -ux
+          gh api \
+              -X GET \
+              -f ref=$REF \
+              -H "Accept: application/vnd.github.raw" \
+              "/repos/$REPOSITORY/contents/RELEASE_NOTES.md" \
+            > RELEASE_NOTES.md
+        env:
+          REF: ${{ github.ref }}
+          REPOSITORY: ${{ github.repository }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Create GitHub release
+        run: |
+          set -ux
+          extra_opts=
+          if echo "$REF_NAME" | grep -- -; then extra_opts=" --prerelease"; fi
+          gh release create \
+            -R "$REPOSITORY" \
+            --discussion-category announcements \
+            --notes-file RELEASE_NOTES.md \
+            --generate-notes \
+            $extra_opts \
+            $REF_NAME \
+            dist/*
+        env:
+          REF_NAME: ${{ github.ref_name }}
+          REPOSITORY: ${{ github.repository }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  publish-to-pypi:
+    needs: ["create-github-release"]
     runs-on: ubuntu-20.04
     steps:
       - name: Download dist files
         uses: actions/download-artifact@v3
         with:
           name: frequenz-channels-python-dist
+          path: dist
 
       - name: Publish the Python distribution to PyPI
         uses: pypa/gh-action-pypi-publish@release/v1
         with:
           password: ${{ secrets.PYPI_API_TOKEN }}
-          packages_dir: ./
           skip_existing: true

RELEASE_NOTES.md

@@ -0,0 +1,11 @@
+# `frequenz-channels` Release Notes
+
+## Summary
+
+This is the first public open source release based on the internal SDK version v0.9.0. There are no breaking changes in this release, only changes to the project structure, metadata, and automation. Packages are also now uploaded to PyPI as [`frequenz-channels`](https://pypi.org/project/frequenz-channels/), so this project now can be installed normally via `pip`:
+
+```sh
+python -m pip install frequenz-channels
+```
+
+The GitHub issues were also improved, adding templates for [reporting issues](https://github.com/frequenz-floss/frequenz-channels/issues/new?assignees=&labels=priority%3A%E2%9D%93%2C+type%3Abug&template=bug.yml) and [requesting features](https://github.com/frequenz-floss/frequenz-channels/issues/new?assignees=&labels=part%3A%E2%9D%93%2C+priority%3A%E2%9D%93%2C+type%3Aenhancement&template=feature.yml). Users are also pointed to the [Discussion forums](https://github.com/frequenz-floss/frequenz-channels/issues/new/choose) when trying to open an issue if they have questions instead. Also many labels are assigned automatically on issue and pull request creation.