ci: make overseer independently deployable

.github/workflows/deployment.yml

@@ -0,0 +1,41 @@
+name: create-doubtfire-overseer
+on:
+  push:
+    tags:
+      - 'v*'
+  deployment:
+  workflow_dispatch:
+jobs:
+  docker-overseer:
+    environment: deployment-secrets
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - 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: Setup meta for Overseer
+        id: docker_meta
+        uses: docker/metadata-action@v3
+        with:
+          images: lmsdoubtfire/overseer
+          tags: |
+            type=ref,event=tag
+            type=semver,pattern={{version}}
+            type=semver,pattern={{major}}.{{minor}}
+            type=semver,pattern={{major}}
+      - name: Build and push overseer
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          file: Dockerfile
+          context: .
+          tags: ${{ steps.docker_meta.outputs.tags }}
+          push: true
+      - name: Image digest
+        run: echo ${{ steps.docker_build.outputs.digest }}