Add release workflow for crates.io publishing (#21)

Author: shsms

.github/workflows/release.yaml

@@ -0,0 +1,75 @@
+name: Publish to crates.io
+
+on:
+  push:
+    tags: ['v*']
+
+jobs:
+  test:
+    runs-on: ubuntu-24.04
+
+    steps:
+      - name: Print environment (debug)
+        run: env
+
+      - name: Fetch sources
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      - name: Run tests
+        uses: frequenz-floss/gh-action-cargo-test@v1.0.0
+
+  create-github-release:
+    needs: ["test"]
+    name: Create GitHub release
+    runs-on: ubuntu-24.04
+    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
+    steps:
+      - 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" \
+            --notes-file RELEASE_NOTES.md \
+            --generate-notes \
+            $extra_opts \
+            $REF_NAME
+        env:
+          REF_NAME: ${{ github.ref_name }}
+          REPOSITORY: ${{ github.repository }}
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+  publish:
+    needs: ["create-github-release"]
+    runs-on: ubuntu-24.04
+    environment: release
+    permissions:
+      id-token: write
+    steps:
+      - uses: actions/checkout@v5
+      - uses: rust-lang/crates-io-auth-action@b7e9a28eded4986ec6b1fa40eeee8f8f165559ec  # v1.0.3
+        id: auth
+      - run: cargo publish
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ steps.auth.outputs.token }}