[bazel] Added manual workflow to publish a tag to BCR (#192)

Adds the publish.yaml workflow to manually release a tag to the Bazel Central Registry (BCR). This workflow uses the official reusable publish-to-bcr workflow from the bazel team.

BCR template files are added to mirror the existing files in the latest manual bcr release for gz-utils.

Also added the compatibility_level field in MODULE.bazel to mirror what is set in BCR for the latest release.

Signed-off-by: Shameek Ganguly <[email protected]>

Author: shameekganguly

.bcr/metadata.template.json

@@ -0,0 +1,16 @@
+{
+    "homepage": "https://github.com/gazebosim/gz-utils",
+    "maintainers": [
+        {
+            "email": "[email protected]",
+            "github": "mjcarroll",
+            "github_user_id": 279701,
+            "name": "Michael Carroll"
+        }
+    ],
+    "repository": [
+        "github:gazebosim/gz-utils"
+    ],
+    "versions": [],
+    "yanked_versions": {}
+}

.bcr/presubmit.yml

@@ -0,0 +1,20 @@
+matrix:
+  platform:
+  - debian10
+  - ubuntu2204
+  - ubuntu2404
+  - macos
+  - macos_arm64
+  bazel:
+  - 8.x
+  - 7.x
+tasks:
+  verify_targets:
+    name: Verify build targets
+    platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_flags:
+    - '--cxxopt=-std=c++17'
+    - '--host_cxxopt=-std=c++17'
+    build_targets:
+    - '@gz-utils//:*'

.bcr/source.template.json

@@ -0,0 +1,5 @@
+{
+  "integrity": "",
+  "strip_prefix": "{REPO}-{TAG}",
+  "url": "https://github.com/{OWNER}/{REPO}/archive/refs/tags/{TAG}.tar.gz"
+}

.github/workflows/publish.yaml

@@ -0,0 +1,44 @@
+# Publish new releases to Bazel Central Registry.
+name: Publish to BCR
+on:
+  # For now, the workflow must be manually triggered.
+  workflow_dispatch:
+    inputs:
+      tag_name:
+        description: git tag being released
+        required: true
+        type: string
+jobs:
+  # The publish-to-bcr reusable workflow expects the version name to be in
+  # semver-(optional build metadata postfix) format, but the repo tags are in
+  # branch_semver-postfix format. This job extracts the branch name as a prefix
+  # to pass to publish-to-bcr.
+  extract_tag_prefix:
+    runs-on: ubuntu-latest
+    outputs:
+      prefix: ${{ steps.extract.outputs.prefix }}
+    steps:
+      - name: Extract the tag prefix from the tag name.
+        id: extract
+        run: |
+          branch=$(echo "${{ inputs.tag_name }}" | cut -d'_' -f1)
+          prefix="${branch}_"
+          echo "prefix=${prefix}" | tee -a "$GITHUB_OUTPUT"
+
+  publish:
+    needs: extract_tag_prefix
+    uses: bazel-contrib/publish-to-bcr/.github/workflows/[email protected]
+    with:
+      tag_name: ${{ inputs.tag_name }}
+      # GitHub repository which is a fork of the upstream where the Pull Request will be opened.
+      registry_fork: gazebo-forks/bazel-central-registry
+      attest: false
+      tag_prefix: ${{ needs.extract_tag_prefix.outputs.prefix }}
+
+    permissions:
+      attestations: write
+      contents: write
+      id-token: write
+    secrets:
+      # Necessary to push to the BCR fork, and to open a pull request against a registry
+      publish_token: ${{ secrets.publish_token || secrets.BCR_PUBLISH_TOKEN }}

MODULE.bazel

@@ -2,6 +2,7 @@
 
 module(
     name = "gz-utils",
+    compatibility_level = 0,
 )
 
 bazel_dep(name = "buildifier_prebuilt", version = "8.2.0.2")