ci: Rewrite release workflows

This adopts release-please to manage releases and changelogs, similar
to other shaka-project repos.

.github/workflows/README.md

@@ -8,12 +8,21 @@
  - `build-docs.yaml`:
    Build Packager docs.  Runs only on Linux.
 
- - `docker-image.yaml`:
+ - `build-docker.yaml`:
    Build the official Docker image.
 
  - `lint.yaml`:
    Lint Shaka Packager.
 
+ - `publish-docs.yaml`:
+   Publish Packager docs.  Runs on the latest release.
+
+ - `publish-docker.yaml`:
+   Publish the official docker image.  Runs on all releases.
+
+ - `publish-npm.yaml`:
+   Publish binaries to NPM.  Runs on all releases.
+
  - `test-linux-distros.yaml`:
    Test the build on all Linux distros via docker.
 
@@ -22,30 +31,32 @@
    - `lint.yaml`
    - `build.yaml`
    - `build-docs.yaml`
-   - `docker-image.yaml`
+   - `build-docker.yaml`
    - `test-linux-distros.yaml`
 
- - On release tag (`github-release.yaml`):
-   - Create a draft release
-   - Invoke:
-     - `lint.yaml`
-     - `build.yaml`
-     - `test-linux-distros.yaml`
-   - Publish the release with binaries from `build.yaml` attached
-
- - On release published:
-   - `docker-hub-release.yaml`, publishes the official Docker image
-   - `npm-release.yaml`, publishes the official NPM package
-   - `update-docs.yaml`:
-     - Invoke `build-docs.yaml`
-     - Push the output to the `gh-pages` branch
+## Release workflow
+ - `release-please.yaml`
+   - Updates changelogs, version numbers based on conventional commits syntax
+     and semantic versioning
+     - https://conventionalcommits.org/
+     - https://semver.org/
+   - Generates/updates a PR on each push
+   - When the PR is merged, runs additional steps:
+     - Creates a GitHub release
+     - Invokes `publish-docs.yaml` to publish the docs
+     - Invokes `publish-docker.yaml` to publish the docker image
+     - Invokes `build.yaml`
+     - Attaches the binaries from `build.yaml` to the GitHub release
+     - Invokes `publish-npm.yaml` to publish the binaries to NPM
 
 ## Common workflows from shaka-project
  - `sync-labels.yaml`
  - `update-issues.yaml`
  - `validate-pr-title.yaml`
 
 ## Required Repo Secrets
+ - `RELEASE_PLEASE_TOKEN`: A PAT for `shaka-bot` to run the `release-please`
+   action
  - `DOCKERHUB_CI_USERNAME`: The username of the Docker Hub CI account
  - `DOCKERHUB_CI_TOKEN`: An access token for Docker Hub
    - To generate, visit https://hub.docker.com/settings/security

.github/workflows/docker-image.yaml → .github/workflows/build-docker.yaml

@@ -29,7 +29,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v3
         with:
-          ref: ${{ github.event.inputs.ref || github.ref }}
+          ref: ${{ github.event.inputs.ref }}
           submodules: recursive
 
       - name: Build

.github/workflows/build-docs.yaml

@@ -61,6 +61,11 @@ jobs:
           cp -a build/doxygen/html gh-pages/docs
           cp docs/index.html gh-pages/index.html
 
+      - name: Upload docs artifacts
+        uses: actions/upload-pages-artifact@v2
+        with:
+          path: gh-pages
+
       - name: Debug
         uses: mxschmitt/action-tmate@v3.6
         with:

.github/workflows/lint.yaml

@@ -45,8 +45,8 @@ jobs:
 
           # NOTE: Must use base.sha instead of base.ref, since we don't have
           # access to the branch name that base.ref would give us.
-          # NOTE: Must also use fetch-depth: 2 in actions/checkout to have access
-          # to the base ref for comparison.
+          # NOTE: Must also use fetch-depth: 2 in actions/checkout to have
+          # access to the base ref for comparison.
           packager/tools/git/check_formatting.py \
               --binary /usr/bin/clang-format \
               ${{ github.event.pull_request.base.sha || 'HEAD^' }}

.github/workflows/pr.yaml

@@ -59,7 +59,7 @@ jobs:
   official_docker_image:
     needs: lint
     name: Official Docker image
-    uses: ./.github/workflows/docker-image.yaml
+    uses: ./.github/workflows/build-docker.yaml
     with:
       ref: ${{ github.event.inputs.ref || github.ref }}
 

.github/workflows/docker-hub-release.yaml → .github/workflows/publish-docker.yaml

@@ -4,39 +4,39 @@
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd
 
-name: Docker Hub Release
+# A workflow to publish the official docker image.
+name: Publish to Docker Hub
 
-# Runs when a new release is published on GitHub.
-# Creates a corresponding Docker Hub release and publishes it.
-#
+# Runs when called from another workflow.
 # Can also be run manually for debugging purposes.
 on:
-  release:
-    types: [published]
+  workflow_call:
+    inputs:
+      tag:
+        required: true
+        type: string
+      latest:
+        required: true
+        type: boolean
   # For manual debugging:
   workflow_dispatch:
     inputs:
-      ref:
-        description: "The tag to release to Docker Hub."
+      tag:
+        description: The tag to build from and to push to.
+        required: True
+      latest:
+        description: If true, push to the "latest" tag.
         required: True
 
 jobs:
   publish_docker_hub:
     name: Publish to Docker Hub
     runs-on: ubuntu-latest
     steps:
-      - name: Compute ref
-        id: ref
-        # We could be building from a workflow dispatch (manual run), or a
-        # release event.  Subsequent steps can refer to $TARGET_REF to
-        # determine the correct ref in all cases.
-        run: |
-          echo "TARGET_REF=${{ github.event.inputs.ref || github.event.release.tag_name }}" >> $GITHUB_ENV
-
       - name: Checkout code
         uses: actions/checkout@v3
         with:
-          ref: ${{ env.TARGET_REF }}
+          ref: ${{ github.event.inputs.tag }}
           submodules: recursive
 
       - name: Log in to Docker Hub
@@ -49,4 +49,11 @@ jobs:
         uses: docker/build-push-action@v2
         with:
           push: true
-          tags: ${{ secrets.DOCKERHUB_PACKAGE_NAME }}:latest,${{ secrets.DOCKERHUB_PACKAGE_NAME }}:${{ env.TARGET_REF }}
+          tags: ${{ secrets.DOCKERHUB_PACKAGE_NAME }}:${{ github.event.inputs.tag }}
+
+      - name: Push to Docker Hub as "latest"
+        if: ${{ github.event.inputs.latest }}
+        uses: docker/build-push-action@v2
+        with:
+          push: true
+          tags: ${{ secrets.DOCKERHUB_PACKAGE_NAME }}:latest