Issue GitHub releases by way of a GHA workflow

When GitHub receives a pushed Git tag that matches a given pattern,
prepare both release notes and a source code archive and use them in a
newly issued GitHub release.

Author: seh

.bcr/config.yml

@@ -0,0 +1,3 @@
+fixedReleaser:
+  login: seh
+  email: [email protected]

.bcr/source.template.json

@@ -1,5 +1,5 @@
 {
     "integrity": "",
     "strip_prefix": "{REPO}-{VERSION}",
-    "url": "https://github.com/{OWNER}/{REPO}/archive/refs/tags/{TAG}.tar.gz"
+    "url": "https://github.com/{OWNER}/{REPO}/releases/download/{TAG}/vcs-archive-{TAG}.tar.gz"
 }

.github/actions/build-test/action.yaml

@@ -0,0 +1,27 @@
+name: Build and Test
+description: |
+  Build all eligible Bazel targets and run all available
+  tests, confirming that they all pass.
+runs:
+  using: composite
+  steps:
+  - name: Cache Bazel-related artifacts
+    uses: actions/cache@v3
+    env:
+      cache-name: bazel-cache
+    with:
+      path: |
+        ~/.cache/bazelisk
+        ~/.cache/bazel
+      key: ${{ runner.os }}-${{ env.cache-name }}
+  - name: Build all Bazel targets
+    run: |
+      bazel build \
+        //...
+    shell: bash
+  - name: Test all Bazel targets
+    run: |
+      bazel test \
+        --test_output=errors \
+        //...
+    shell: bash

.github/workflows/ci.yaml

@@ -1,45 +1,23 @@
 name: Continuous Integration
 on:
   # See https://docs.github.com/en/actions/reference/events-that-trigger-workflows.
-  push:
-    branches:
-    - main
-    tags:
-    - v*
   pull_request:
 jobs:
   bazel-source-inspection:
     runs-on: ubuntu-latest
     steps:
     - name: Check out VCS repository
-      uses: actions/checkout@v2
+      uses: actions/checkout@v3
     - name: Confirm Bazel files is formatted per "buildifier"
       uses: thompsonja/[email protected]
       with:
         # See https://github.com/bazelbuild/buildtools/blob/master/WARNINGS.md.
         warnings: -function-docstring,-module-docstring
+        buildifier_version: 6.1.0
   build-test:
     runs-on: ubuntu-latest
     steps:
-    - name: Cache bazel-related artifacts
-      uses: actions/cache@v3
-      env:
-        cache-name: bazel-cache
-      with:
-        path: |
-          ~/.cache/bazelisk
-          ~/.cache/bazel
-        key: ${{ runner.os }}-${{ env.cache-name }}
     - name: Check out VCS repository
       uses: actions/checkout@v3
-    - name: Build all Bazel targets
-      run: |
-        bazel build \
-          --enable_bzlmod \
-          //...
-    - name: Test all Bazel targets
-      run: |
-        bazel test \
-          --enable_bzlmod \
-          --test_output=errors \
-          //...
+    - name: Build and test all Bazel targets
+      uses: ./.github/actions/build-test

.github/workflows/prepare-release

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+
+# This program is adapted from "release_prep.sh" in rules_template:
+# https://github.com/bazel-contrib/rules-template/blob/main/.github/workflows/release_prep.sh
+
+set -e -u -o pipefail
+
+ruleset_name="$1"
+shift
+if [ -z "${ruleset_name}" ]; then
+  echo >&2 'Bazel ruleset name must not be empty.'
+  exit 1
+fi
+
+if (( $# < 1 )); then
+  git_tag="${GITHUB_REF_NAME:-}"
+else
+  git_tag="$1"
+  shift
+fi
+if [ -z "${git_tag}" ]; then
+  echo >&2 'Git tag to use for release must not be empty.'
+  exit 1
+fi
+
+# The prefix is chosen to match what GitHub generates for its own
+# source archives.
+git archive \
+    --format=tar \
+    --prefix="${ruleset_name}-${git_tag:1}/" \
+    "${git_tag}" \
+  | gzip > "vcs-archive-${git_tag}.tar.gz"
+
+tag_annotation_subject=$(git tag --list --format='%(contents:subject)' "${git_tag}")
+if [ -n "${tag_annotation_subject}" ]; then
+  echo "# ${tag_annotation_subject}"
+  tag_annotation_body=$(git tag --list --format='%(contents:body)' "${git_tag}")
+  if [ -n "${tag_annotation_body}" ]; then
+    echo "
+${tag_annotation_body}
+"
+  fi
+  echo "# Details"
+fi
+
+cat << EOF
+## Using modules with Bazel 6 and later
+
+1. Enable support for modules in your _.bazelrc_ file by adding the following line:
+  \`common --enable_bzlmod\`
+1. Add the following directive to your _MODULE.bazel_ file:
+\`\`\`starlark
+bazel_dep(name = "${ruleset_name}", version = "${git_tag:1}")
+\`\`\`
+EOF

.github/workflows/release.yaml

@@ -0,0 +1,30 @@
+name: Release
+on:
+  # See https://docs.github.com/en/actions/reference/events-that-trigger-workflows.
+  push:
+    tags:
+    - "v*.*.*"
+jobs:
+  release:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out VCS repository
+      uses: actions/checkout@v3
+    - name: Build and test all Bazel targets
+      uses: ./.github/actions/build-test
+    - name: Prepare release notes and artifacts
+      run: |
+        gh_repository="${{ github.repository }}"
+        ref_name="${{ github.ref_name }}"
+        tag_name="${ref_name#refs/heads/}"
+        .github/workflows/prepare-release \
+          "${gh_repository#*/}" \
+          "${tag_name}" \
+        > release-notes.txt
+    - name: Issue release
+      uses: softprops/action-gh-release@v1
+      with:
+        generate_release_notes: true
+        body_path: release-notes.txt
+        files: vcs-archive-*.tar.gz
+        fail_on_unmatched_files: true