first add

server/Dockerfile.caddy-l4

@@ -0,0 +1,36 @@
+# ========= Stage 1: （可选）你的前端静态资源构建 =========
+FROM node:lts-alpine AS ui-builder
+WORKDIR /src
+COPY headscale-ui/package*.json ./
+RUN npm ci
+COPY headscale-ui/ .
+RUN npm run build
+
+# ========= Stage 2: 用 Go 1.25 (Alpine) 构建 Caddy + 插件 =========
+FROM golang:1.25.0-alpine3.22 AS caddy-builder
+
+RUN echo "https://mirrors.aliyun.com/alpine/v3.22/main" > /etc/apk/repositories && \
+    echo "https://mirrors.aliyun.com/alpine/v3.22/community" >> /etc/apk/repositories && \
+    apk update && \
+    apk add --no-cache git build-base ca-certificates
+
+ENV GOPROXY=https://goproxy.cn,direct
+ENV GOTOOLCHAIN=local
+
+RUN go install github.com/caddyserver/xcaddy/cmd/xcaddy@latest
+
+# 用 xcaddy 构建 (保持与用户提供版本一致/可调整)
+RUN /go/bin/xcaddy build v2.10.1 \
+    --output /usr/local/bin/caddy \
+    --with github.com/caddy-dns/alidns@v1.0.26 \
+    --with github.com/caddy-dns/cloudflare@v0.2.1 \
+    --with github.com/mholt/caddy-l4
+
+# ========= Stage 3: 运行时镜像（Alpine） =========
+FROM caddy:2.10.0-alpine
+COPY --from=caddy-builder /usr/local/bin/caddy /usr/bin/caddy
+COPY --from=ui-builder /src/build /usr/src/www
+
+RUN apk update && \
+    apk add --no-cache bind-tools netcat-openbsd jq curl && \
+    mkdir -p /data/log/headscale