Build Caddy with the caddy-dns/desec module

Stock caddy:2-alpine plus caddy-dns/desec, for ACME DNS-01 against zones
hosted at deSEC (*.llm.aneur.in in cloud/cloud's llm stack). CI builds
and checks the module on pull requests, and pushes :latest (keeping
:previous) on main, weekly and by hand.

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

.gitea/workflows/build.yml

@@ -0,0 +1,44 @@
+name: Build
+
+on:
+  push:
+    branches: [main]
+  schedule:
+    # Weekly, so new Caddy and caddy-dns/desec releases land without a commit.
+    - cron: "17 4 * * 1"
+  workflow_dispatch:
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    container:
+      image: docker:cli
+    env:
+      IMAGE: code.aneur.in/${{ gitea.repository }}
+    steps:
+      - name: Install Node (for checkout)
+        run: apk add --no-cache nodejs
+
+      - uses: actions/checkout@v4
+
+      - name: Build
+        run: docker build --pull --tag "$IMAGE:latest" .
+
+      - name: Check the deSEC module is built in
+        run: docker run --rm "$IMAGE:latest" caddy list-modules | grep -x dns.providers.desec
+
+      - name: Log in to the container registry
+        env:
+          BUILD_API_TOKEN: ${{ secrets.BUILD_API_TOKEN }}
+        run: echo "$BUILD_API_TOKEN" | docker login code.aneur.in -u "${{ gitea.actor }}" --password-stdin
+
+      - name: Promote current "latest" to "previous"
+        run: |
+          if docker buildx imagetools inspect "$IMAGE:latest" >/dev/null 2>&1; then
+            docker buildx imagetools create -t "$IMAGE:previous" "$IMAGE:latest"
+          else
+            echo "No existing :latest to promote; skipping."
+          fi
+
+      - name: Push "latest"
+        run: docker push "$IMAGE:latest"

.gitea/workflows/pr-checks.yml

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+name: PR Checks
+
+on:
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+jobs:
+  checks:
+    runs-on: ubuntu-latest
+    container:
+      image: docker:cli
+    steps:
+      - name: Install Node (for checkout)
+        run: apk add --no-cache nodejs
+
+      - uses: actions/checkout@v4
+
+      - name: Build
+        run: docker build --pull --tag caddy-desec-docker:check .
+
+      - name: Check the deSEC module is built in
+        run: docker run --rm caddy-desec-docker:check caddy list-modules | grep -x dns.providers.desec

Dockerfile

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+# Caddy with the caddy-dns/desec module, for ACME DNS-01 challenges against
+# zones hosted at deSEC. Otherwise the stock caddy:2-alpine image.
+
+FROM caddy:2-builder AS builder
+RUN xcaddy build --with github.com/caddy-dns/desec
+
+FROM caddy:2-alpine
+COPY --from=builder /usr/bin/caddy /usr/bin/caddy

README.md

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+# caddy-desec-docker
+
+Stock [Caddy](https://caddyserver.com) plus the
+[caddy-dns/desec](https://github.com/caddy-dns/desec) module, so Caddy can
+get certificates by ACME DNS-01 against a zone hosted at
+[deSEC](https://desec.io). Published as
+`code.aneur.in/cloud/caddy-desec-docker:latest` (linux/amd64).
+
+Used by the `llm` stack in [cloud/cloud](https://code.aneur.in/cloud/cloud)
+for `*.llm.aneur.in`:
+
+```
+{
+	acme_dns desec {
+		token {env.DESEC_TOKEN}
+	}
+}
+```
+
+## Builds
+
+- **Push to `main`, weekly, or by hand** (`build.yml`): builds the image,
+  checks the deSEC module is present, then pushes `:latest`, keeping the
+  previous one as `:previous`. The weekly run picks up new Caddy and module
+  releases without a commit.
+- **Pull requests** (`pr-checks.yml`): the same build and module check,
+  without pushing.
+
+The push uses the `BUILD_API_TOKEN` Actions secret, a Gitea token with
+package write access.