Publish image on master merged changes

As we are pretty much committed to github actions, we should
probably rely on it to push the images at each commit merged
on the master branch.

.github/workflows/on-master-push.yaml

@@ -0,0 +1,38 @@
+# We publish every merged commit in the form of an image
+# named kured:<branch>-<short tag>
+name: Push image of latest master
+on:
+  push:
+    branches:
+      - master
+jobs:
+  tag-scan-and-push-final-image:
+    name: "Build, scan, and publish tagged image"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+
+      - name: Find go version
+        run: |
+          GO_VERSION=$(awk '/^go/ {print $2};' go.mod)
+          echo "::set-output name=version::${GO_VERSION}"
+        id: awk_gomod
+
+      - name: Ensure go version
+        uses: actions/setup-go@v2
+        with:
+          go-version: "${{ steps.awk_gomod.outputs.version }}"
+
+      - name: Login to DockerHub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME_WEAVEWORKSKUREDCI }}
+          password: ${{ secrets.DOCKERHUB_TOKEN_WEAVEWORKSKUREDCI }}
+
+      - name: Build image
+        run: |
+          make DH_ORG="${{ github.repository_owner }}" image
+
+      - name: Publish image
+        run: |
+          make DH_ORG="${{ github.repository_owner }}" publish-image