Added tag based image build workflow for gh actions (#107)

* Added tag based image build workflow for gh actions

* updated job name

.github/workflows/tagBasedImageBuild.yml

@@ -0,0 +1,40 @@
+name: Tag Based Image Build
+
+on:
+  create: # This listens to create events, which includes tag creations
+
+jobs:
+  buildImageForNewTag:
+    if: startsWith(github.ref, 'refs/tags/') # Only run this job when a tag is created
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Verify tag is on main branch
+        run: |
+          TAG_COMMIT=$(git rev-list -n 1 ${{ github.ref }})
+          MAIN_BRANCH_COMMIT=$(git rev-list -n 1 main)
+          if [ "$TAG_COMMIT" != "$MAIN_BRANCH_COMMIT" ]; then
+            echo "Tag is not on the main branch, aborting!"
+            exit 1
+          fi
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Build and Push Docker Image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          target: prod
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: thirdweb/web3-api:${{ github.ref_name }} # Set the docker tag to the Git tag name