Github: Add workflows for build and publish of Docker images

.github/workflows/build-image.yml

@@ -0,0 +1,24 @@
+name: Docker image build
+
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Build the Docker image
+      run: >-
+        docker build . \
+          --file docker/Dockerfile \
+          --build-arg=BUILD_SERIES=dev \
+          --build-arg=BUILD_ID="$(echo "$GITHUB_SHA" | head -c 12)" \
+          --tag snikket/snikket-web-portal:dev
+    - name: Log into registry
+      run: echo "${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}" | docker login -u snikket --password-stdin
+    - name: Push the Docker image
+      run: docker push snikket/snikket-web-portal:dev

.github/workflows/build-release-image.yml

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+---
+name: Docker release image build
+
+"on":
+  push:
+    tags:
+      - release/*.*
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Build the Docker image
+        run: >-
+          echo "Building ref $GITHUB_REF...";
+          RELEASE_TAG="${GITHUB_REF#refs/tags/release/}";
+          RELEASE_SERIES="${RELEASE_TAG%.*}";
+          RELEASE_VER="${RELEASE_TAG#$RELEASE_SERIES.}";
+          docker build . \
+            --file docker/Dockerfile \
+            --build-arg=BUILD_SERIES="$RELEASE_SERIES" \
+            --build-arg=BUILD_ID="$RELEASE_VER" \
+            --tag snikket/snikket-web-portal:"$RELEASE_SERIES"
+      - name: Log into registry
+        run: echo "${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}" | docker login -u snikket --password-stdin
+      - name: Push the Docker image
+        run: >-
+          RELEASE_TAG="${GITHUB_REF#refs/tags/release/}";
+          RELEASE_SERIES="${RELEASE_TAG%.*}";
+          docker push snikket/snikket-web-portal:"$RELEASE_SERIES"