Create docker-image.yml (#871)

.github/workflows/docker-image.yml

@@ -0,0 +1,24 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        docker-image: ['gerbil', 'gerbilxx']
+    steps:
+    - uses: actions/checkout@v3
+    - name: Build the Docker image
+      run: make -C docker ${{ matrix.docker-image }}
+    - name: docker push to dockerhub
+      run: |
+        docker login -u gerbil -p ${{ secrets.DOCKER_TOKEN }}
+        docker push gerbil/${{ matrix.docker-image }}:$(uname -m)