ci: add publish workflow (on tags)

Author: tommytroen

.github/workflows/publish-release.yml

@@ -0,0 +1,37 @@
+name: Publish release
+
+on:
+  release:
+    types: [published]
+
+jobs:
+  publish-release:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout latest code
+        uses: actions/checkout@v2
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11
+
+      - name: Setup build cache
+        uses: actions/cache@v1
+        with:
+          path: ~/.gradle/caches
+          key: ${{ runner.os }}-gradle-${{ hashFiles('**/*.gradle.kts') }}
+          restore-keys: |
+            ${{ runner.os }}-gradle-
+      - name: Publish artifact
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+        # The GITHUB_REF tag comes in the format 'refs/tags/xxx'.
+        # So if we split on '/' and take the 3rd value, we can get the release name.
+        run: |
+          NEW_VERSION=$(echo "${GITHUB_REF}" | cut -d "/" -f3)
+          echo "New version: ${NEW_VERSION}"
+          echo "Github username: ${GITHUB_ACTOR}"
+          ./gradlew -Pversion=${NEW_VERSION} publish