Add Docker job for releases.

See #3

.github/workflows/release.yml

@@ -4,6 +4,35 @@ on:
     tags:
       - 'v[0-9]+.[0-9]+.[0-9]+'
 jobs:
+  docker-push:
+    name: docker-push
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 1
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
+        with:
+          images: aramperes/onetun
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}
+
   create-release:
     name: create-release
     runs-on: ubuntu-latest