Add a Docker workflow that publishes multi-arch images

Pushes :edge for main and :x.y.z, :x.y and :latest for release tags,
optionally mirrored to another registry. The release workflow no longer
builds the image itself, so a tag does not publish it twice. The README
covers running the image anywhere and the settings the workflows read.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

.gitea/workflows/docker.yml

@@ -0,0 +1,87 @@
+name: Docker
+
+# Publishes the container image (linux/amd64 and linux/arm64):
+#   push to main   ->  :edge and :sha-<commit>
+#   tag v1.2.3     ->  :1.2.3, :1.2 and :latest   (pre-releases like v1.2.3-rc1 get only :1.2.3-rc1)
+# Run it by hand from the Actions tab to rebuild the current branch.
+#
+# Settings (all optional):
+#   secret   REGISTRY_TOKEN   access token with package write permission, if the job token can't push
+#   variable REGISTRY_USER    user for that token (defaults to the person who triggered the run)
+#   variable MIRROR_IMAGE     also push to another registry, e.g. ghcr.io/you/spinner or docker.io/you/spinner
+#   secret   MIRROR_TOKEN     and variable MIRROR_USER: login for that registry
+#   variable PUBLISH_DOCKER   set to "false" to skip this workflow
+on:
+  push:
+    branches: [main]
+    tags: ['v*']
+  workflow_dispatch:
+
+jobs:
+  image:
+    if: ${{ vars.PUBLISH_DOCKER != 'false' }}
+    runs-on: ubuntu-latest
+    env:
+      GOPRIVATE: git.veillax.com
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+
+      - name: Let Go fetch modules from this server
+        run: git config --global url."https://x-access-token:${{ secrets.GITHUB_TOKEN }}@git.veillax.com/".insteadOf "https://git.veillax.com/"
+
+      - name: Test
+        run: |
+          go vet ./...
+          go test ./...
+
+      # The Dockerfile packages these binaries, so the image needs no Go toolchain or emulation.
+      - name: Build the binaries
+        env:
+          TARGETS: linux/amd64 linux/arm64
+        run: sh deploy/build.sh
+
+      - name: Log in
+        env:
+          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN || secrets.GITHUB_TOKEN }}
+          REGISTRY_USER: ${{ vars.REGISTRY_USER || github.actor }}
+          MIRROR_IMAGE: ${{ vars.MIRROR_IMAGE }}
+          MIRROR_USER: ${{ vars.MIRROR_USER }}
+          MIRROR_TOKEN: ${{ secrets.MIRROR_TOKEN }}
+        run: |
+          host=${GITHUB_SERVER_URL#*://}
+          echo "$REGISTRY_TOKEN" | docker login "$host" -u "$REGISTRY_USER" --password-stdin
+          if [ -n "$MIRROR_IMAGE" ]; then
+            echo "$MIRROR_TOKEN" | docker login "${MIRROR_IMAGE%%/*}" -u "$MIRROR_USER" --password-stdin
+          fi
+
+      - name: Build and push
+        env:
+          MIRROR_IMAGE: ${{ vars.MIRROR_IMAGE }}
+        run: |
+          host=${GITHUB_SERVER_URL#*://}
+          owner=$(echo "$GITHUB_REPOSITORY_OWNER" | tr 'A-Z' 'a-z')
+          images="$host/$owner/spinner"
+          [ -n "$MIRROR_IMAGE" ] && images="$images $MIRROR_IMAGE"
+
+          if [ "$GITHUB_REF_TYPE" = tag ]; then
+            v=${GITHUB_REF_NAME#v}
+            tags="$v"
+            case "$v" in
+              *-*) ;; # pre-releases don't move :1.2 or :latest
+              *) tags="$tags ${v%.*} latest" ;;
+            esac
+          else
+            tags="edge sha-$(echo "$GITHUB_SHA" | cut -c1-7)"
+          fi
+
+          args=""
+          for i in $images; do for t in $tags; do args="$args -t $i:$t"; done; done
+          docker buildx create --name spinner --driver docker-container --use >/dev/null 2>&1 || docker buildx use spinner
+          echo "pushing:$args"
+          docker buildx build --platform linux/amd64,linux/arm64 $args --push .

.gitea/workflows/release.yml

@@ -1,6 +1,6 @@
 name: Release
 
-# Push a tag such as v0.2.0 to build and publish a release:
+# Push a tag such as v0.2.0 to publish a release. The Docker workflow builds the image from the same tag:
 #   git tag -a v0.2.0 -m "spinner v0.2.0" && git push origin v0.2.0
 on:
   push:
@@ -37,26 +37,3 @@ jobs:
         env:
           TOKEN: ${{ secrets.RELEASE_TOKEN || secrets.GITHUB_TOKEN }}
         run: sh deploy/publish-release.sh "${GITHUB_REF_NAME}"
-
-      # Skipped when the repository variable PUBLISH_DOCKER is "false", or fails alone
-      # if this runner has no Docker: the release above is already published by then.
-      # Optional secret REGISTRY_TOKEN (and variable REGISTRY_USER): an access token
-      # with package write permission, for servers where the job token can't push.
-      - name: Build and push the container image
-        if: ${{ vars.PUBLISH_DOCKER != 'false' }}
-        env:
-          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN || secrets.GITHUB_TOKEN }}
-          REGISTRY_USER: ${{ vars.REGISTRY_USER || github.actor }}
-        run: |
-          host=${GITHUB_SERVER_URL#*://}
-          owner=$(echo "$GITHUB_REPOSITORY_OWNER" | tr 'A-Z' 'a-z')
-          image="$host/$owner/spinner"
-          echo "$REGISTRY_TOKEN" | docker login "$host" -u "$REGISTRY_USER" --password-stdin
-          # a container-driver builder can build several architectures in one go
-          docker buildx create --name release --driver docker-container --use >/dev/null 2>&1 || docker buildx use release
-          tags="-t $image:$GITHUB_REF_NAME"
-          case "$GITHUB_REF_NAME" in
-            *-*) ;;                       # pre-releases (v1.0.0-rc1) don't move :latest
-            *) tags="$tags -t $image:latest" ;;
-          esac
-          docker buildx build --platform linux/amd64,linux/arm64 $tags --push .

README.md

@@ -48,24 +48,52 @@ All except `/` need `Authorization: Bearer <token>`.
 
 ## Docker
 
+The image is `git.veillax.com/veillax/spinner` for linux/amd64 and linux/arm64. It runs as a non-root user, keeps its config in the `/data` volume, and writes a starter `spinner.json` there on first start. The admin page on port 8080 is the quickest way to add servers; keep it private or behind HTTPS.
+
+| Tag | Meaning |
+| --- | --- |
+| `latest` | The newest release |
+| `1.2.3`, `1.2` | An exact release, or the newest patch of a minor version |
+| `edge` | The latest commit on `main` |
+| `sha-<commit>` | One specific commit |
+
+Run it anywhere Docker runs:
+
 ```
-cp .env.example .env        # set SPINNER_ADMIN_TOKEN
+docker run -d --name spinner --restart unless-stopped \
-docker compose -f deploy/docker-compose.yml up -d
+  -p 25565:25565 -p 127.0.0.1:8080:8080 \
+  -e SPINNER_ADMIN_TOKEN=change-me \
+  -v spinner-data:/data \
+  git.veillax.com/veillax/spinner:latest
 ```
 
-The image is `git.veillax.com/veillax/spinner` (linux/amd64 and linux/arm64). It keeps its config in the `/data` volume and writes a starter `spinner.json` there on first start, so the admin page on port 8080 is the quickest way to add servers. Keep that port private or behind HTTPS.
+Or with Compose: `cp .env.example .env`, set `SPINNER_ADMIN_TOKEN`, then `docker compose -f deploy/docker-compose.yml up -d`. Backends on the Docker host are reachable at `host.docker.internal` (add `--add-host host.docker.internal:host-gateway` on Linux), or put Spinner and the Minecraft containers on one Docker network and use their container names.
+
+If the registry is private, run `docker login git.veillax.com` first.
 
 ## Releases
 
-Push a tag to build archives, publish a release and push the image:
+Push a tag to publish a release and its image:
 
 ```
 git tag -a v0.1.0 -m "spinner v0.1.0" && git push origin v0.1.0
 ```
 
-`.gitea/workflows/release.yml` runs `deploy/build.sh`, uploads the archives with `deploy/publish-release.sh`, then builds and pushes the image. Set the repository variable `PUBLISH_DOCKER` to `false` to skip the image. If the job token cannot write releases or packages, add the secrets `RELEASE_TOKEN` and `REGISTRY_TOKEN` (and the variable `REGISTRY_USER`).
+Two workflows run on the tag:
 
-To build by hand: `sh deploy/build.sh` puts binaries and archives in `dist/`, then `docker buildx build .` packages the linux binary.
+* `.gitea/workflows/release.yml` builds archives with `deploy/build.sh` and uploads them with `deploy/publish-release.sh`.
+* `.gitea/workflows/docker.yml` tests, builds both Linux binaries and pushes the image. It also pushes `edge` on every push to `main`, and can be run by hand from the Actions tab.
+
+Settings, all optional:
+
+| Name | Kind | Use |
+| --- | --- | --- |
+| `REGISTRY_TOKEN`, `REGISTRY_USER` | secret, variable | Token with package write permission, if the job token cannot push |
+| `RELEASE_TOKEN` | secret | Token that can write releases, if the job token cannot |
+| `MIRROR_IMAGE`, `MIRROR_USER`, `MIRROR_TOKEN` | variable, variable, secret | Also push to another registry, for example `ghcr.io/you/spinner` or `docker.io/you/spinner` |
+| `PUBLISH_DOCKER` | variable | Set to `false` to skip the image |
+
+The runner needs Docker with buildx. To build by hand: `sh deploy/build.sh` puts binaries and archives in `dist/`, then `docker buildx build .` packages the linux binary for your platform.
 
 ## Not in v1