ci: deploy to ghcr on push

.github/workflows/ghcr.yml

@@ -0,0 +1,73 @@
+name: Deploy docker image to ghcr
+
+# Deploy docker image to ghcr on pushes to master and all releases/tags.
+# Note releases to docker hub are managed separately in another process
+# (github sends webhooks to docker hub which triggers the build there).
+# This workflow is an alternative form of retention for docker images
+# which also allows us to tag and retain every single commit to master.
+
+on:
+  push:
+    tags:
+      - '*'
+    branches:
+      - master
+  release:
+    types: [released]
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: ${{ github.repository }}
+
+jobs:
+  deploy-ghcr:
+
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+        with:
+            # need to fetch unshallow so that setuptools_scm can infer the version
+            fetch-depth: 0
+
+      - uses: actions/setup-python@v4
+        name: Install python
+        with:
+          python-version: "3.11"
+          cache: "pip"
+
+      - name: Generate vyper/version.py
+        run: |
+          pip install .
+          echo "VYPER_VERSION=$(PYTHONPATH=. python vyper/cli/vyper_compile.py --version)" >> "$GITHUB_ENV"
+
+      - name: Docker meta
+        id: meta
+        uses: docker/metadata-action@v4
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+          flavor: |
+            latest=true
+          tags: |
+            type=ref,event=branch
+            type=ref,event=tag
+            type=raw,value=${{ env.VYPER_VERSION }}
+
+      - name: Login to ghcr.io
+        uses: docker/login-action@v2
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v4
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}