chore(actions): add docker build action

.github/workflows/docker-build.yml

@@ -0,0 +1,38 @@
+name: Build Docker Image
+
+on:
+  push:
+    branches: [main]
+
+jobs:
+  docker:
+    name: Build Docker Image
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout Source code
+        uses: actions/checkout@v2
+      - name: Set up QEMU
+        uses: docker/setup-qemu-action@v1
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v1
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+      - name: Get short hash of commit
+        id: sha_short
+        shell: bash
+        run: echo "::set-output name=sha_short::$(git rev-parse --short HEAD)"
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          file: ./Dockerfile
+          push: true
+          tags: |
+            topgg/digitaloceansnapshotter:${{ steps.sha_short.outputs.sha_short }}
+            topgg/digitaloceansnapshotter:latest
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}