Add GitHub Actions workflow for Docker build and push

Author: TommyMerlin

.github/workflows/main.yml

@@ -0,0 +1,32 @@
+name: Build and Push Docker image
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Check out the code
+      uses: actions/checkout@v2
+    - name: Login Dockerhub
+      uses: docker/login-action@v3.2.0
+      with:
+        # Username used to log against the Docker registry
+        username: ${{ secrets.DOCKER_USERNAME }}
+        # Password or personal access token used to log against the Docker registry
+        password: ${{ secrets.DOCKER_PASSWORD }}
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v1
+
+    - name: Build and push
+      uses: docker/build-push-action@v2
+      with:
+        context: .
+        file: Dockerfile
+        push: true
+        tags: 7ommymerlin/notify-scheduler:latest