chore(docker): optimize image size using Next.js standalone output (#194)

- Switch to Next.js standalone output mode
- Reduce Docker image size from 1.05GB to 224MB
- Decrease compressed image size from 295MB to 74MB
- Remove unnecessary dependencies and files from final stage

This change significantly improves deployment efficiency and reduces
resource usage in production environments.

Dockerfile

@@ -1,24 +1,33 @@
-FROM node:lts-alpine AS builder
-
+# Stage 1: Dependencies
+FROM node:lts-alpine AS deps
 RUN apk add --no-cache pnpm
-
 WORKDIR /app
 COPY package.json pnpm-lock.yaml ./
-RUN pnpm install
+# Need all dependencies for build
+RUN pnpm install --frozen-lockfile
+
+# Stage 2: Builder
+FROM node:lts-alpine AS builder
+RUN apk add --no-cache pnpm
+WORKDIR /app
+COPY --from=deps /app/node_modules ./node_modules
 COPY . .
+# Builds standalone output
 RUN pnpm build
 
-FROM node:lts-alpine
-
+# Stage 3: Runner
+FROM node:lts-alpine AS runner
 WORKDIR /app
-RUN apk add --no-cache pnpm
-COPY package.json pnpm-lock.yaml ./
-RUN pnpm install --prod
-COPY --from=builder /app/.next ./.next
-COPY --from=builder /app/public ./public
-COPY --from=builder /app/next.config.js ./
 
-ENV PORT 3000
 ENV NODE_ENV production
+ENV PORT 3000
+
+# Only copy standalone output - no need for node_modules
+COPY --from=builder /app/public ./public
+COPY --from=builder /app/.next/standalone ./
+COPY --from=builder /app/.next/static ./.next/static
+
+USER node
 EXPOSE 3000
-CMD pnpm start
+# Uses standalone server
+CMD ["node", "server.js"]

next.config.js

@@ -4,6 +4,7 @@ const nextConfig = {
   // The uploader and downloader are both using useEffect to listen for peerjs events
   // which causes the connection to be created twice.
   reactStrictMode: false,
+  output: 'standalone'
 }
 
 module.exports = nextConfig