ci: migrate caddy build to GitHub Actions

- Move build-caddy workflow from Gitea to GitHub Actions
- Make caddy_plugin optional, supporting comma-separated plugins
- Add README documenting workflow usage

.github/workflows/build-caddy.yaml

@@ -8,9 +8,8 @@ on:
         required: true
         default: 'latest'
       caddy_plugin:
-        description: 'Specify plugin module path (e.g., github.com/caddy-dns/cloudflare)'
+        description: 'Comma-separated plugin module paths, e.g. github.com/caddy-dns/cloudflare, github.com/caddyserver/nginx-adapter. Leave empty to build vanilla Caddy.'
-        required: true
+        required: false
-        default: 'github.com/caddy-dns/cloudflare'
 
 jobs:
   build-caddy:
@@ -26,7 +25,16 @@ jobs:
         run: go install github.com/caddyserver/xcaddy/cmd/xcaddy@latest
 
       - name: Compile customised Caddy binary
-        run: xcaddy build ${{ inputs.caddy_version }} --with ${{ inputs.caddy_plugin }}
+        run: |
+          PLUGIN_ARGS=""
+          IFS=',' read -ra PLUGINS <<< "${{ inputs.caddy_plugin }}"
+          for PLUGIN in "${PLUGINS[@]}"; do
+            PLUGIN="${PLUGIN// /}"
+            if [ -n "$PLUGIN" ]; then
+              PLUGIN_ARGS="$PLUGIN_ARGS --with $PLUGIN"
+            fi
+          done
+          xcaddy build ${{ inputs.caddy_version }} $PLUGIN_ARGS
 
       - name: Upload compiled artefact
         uses: actions/upload-artifact@v3

README.md

@@ -0,0 +1,60 @@
+# infra
+
+The infrastructure repository of onixbyte, hosting the CI workflows used to build and maintain the runtime environment.
+
+## Directory structure
+
+```
+infra/
+└── .github/workflows/
+    └── build-caddy.yaml   # GitHub Actions workflow that builds a customised Caddy binary
+```
+
+## Building a customised Caddy
+
+The `build-caddy.yaml` workflow uses [xcaddy](https://github.com/caddyserver/xcaddy) to compile a specified version of Caddy with plugins injected, and uploads the compiled binary as an artefact. The workflow can only be triggered manually.
+
+### How to trigger the build
+
+1. Open the **Actions** page of the repository.
+2. Select the **Build Customised Caddy** workflow from the left-hand panel.
+3. Click **Run workflow** and fill in the parameters (see the table below).
+4. Wait for the build to finish, then download the `caddy-custom-linux-amd64` artefact from the build run page.
+
+### Input parameters
+
+| Parameter | Description | Required | Default |
+|-----------|-------------|:---:|---------|
+| `caddy_version` | Caddy version to build, e.g. `latest`, `v2.8.4` | Yes | `latest` |
+| `caddy_plugin` | Comma-separated plugin module paths, e.g. `github.com/caddy-dns/cloudflare, github.com/caddyserver/nginx-adapter`. Leave empty to build vanilla Caddy. | No | — |
+
+### Plugin input behaviour
+
+The table below shows how the value of `caddy_plugin` maps to the actual `xcaddy` command (using the default `latest` version):
+
+| Input (`caddy_plugin`) | Command that runs |
+|------------------------|-------------------|
+| `github.com/caddy-dns/cloudflare, github.com/caddyserver/nginx-adapter` | `xcaddy build latest --with github.com/caddy-dns/cloudflare --with github.com/caddyserver/nginx-adapter` |
+| `github.com/caddy-dns/cloudflare,github.com/caddyserver/nginx-adapter` | Same as above (spaces are optional) |
+| `github.com/caddy-dns/cloudflare` | `xcaddy build latest --with github.com/caddy-dns/cloudflare` |
+| *(empty)* | `xcaddy build latest` (vanilla Caddy) |
+
+> Empty entries are skipped automatically, so `plugin1, , plugin2` behaves the same as `plugin1, plugin2`.
+
+## Building locally
+
+To reproduce the same build on your own machine you need Go 1.22+:
+
+```sh
+go install github.com/caddyserver/xcaddy/cmd/xcaddy@latest
+
+# Compile a specific version with a plugin injected
+xcaddy build v2.8.4 --with github.com/caddy-dns/cloudflare
+
+# Inject several plugins at once
+xcaddy build latest \
+  --with github.com/caddy-dns/cloudflare \
+  --with github.com/caddyserver/nginx-adapter
+```
+
+When the build finishes, an executable named `caddy` is produced in the current directory.