ci: create tag and release Docker image (#87)

.github/workflows/release.yaml

@@ -0,0 +1,45 @@
+name: Docker release
+
+on:
+  push:
+    tags:
+      - v[0-9]+.[0-9]+.[0-9]+
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: smee.io
+
+jobs:
+  image:
+    name: Build and push Docker image
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Check out the repo
+        uses: actions/checkout@v2
+
+      - run: echo ${{ github.actor }}
+
+      - name: Log in to the Container registry
+        uses: docker/login-action@v1
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata
+        id: meta
+        uses: docker/metadata-action@v3
+        with:
+          images: ${{ env.REGISTRY }}/${{ github.repository_owner }}/${{ env.IMAGE_NAME }}
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: ${{ steps.meta.outputs.tags }}
+          labels: ${{ steps.meta.outputs.labels }}

.github/workflows/tag.yaml

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+name: Create tag
+
+on:
+  pull_request:
+    branches:
+      - master
+    types:
+      - closed
+    paths-ignore:
+      - LICENSE
+      - README.md
+      - .github/**
+      - .*
+
+permissions:
+  contents: read
+  packages: read
+
+jobs:
+  tag:
+    name: Tagging
+    runs-on: ubuntu-latest
+    if: github.event.pull_request.merged == true
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: Create new tag
+        id: version
+        run: |
+            LAST_TAG=$(git tag --sort=creatordate --sort=v:refname | tail -n1)
+            NEW_TAG=$(echo "$LAST_TAG" | awk '{split(substr($0, 2), a, "."); printf "v%d.%d.%d", a[1], a[2], a[3]+1}')
+            git tag $NEW_TAG
+            git push --tags