Improved docker image (size & speed)

Dockerfile

@@ -1,27 +1,42 @@
-FROM node:18-slim AS frontend-builder
+# Stage 1: on frontend dependency change
+FROM node:18-alpine AS frontend-dependencies
 WORKDIR /opt/app
 COPY frontend/package.json frontend/package-lock.json ./
 RUN npm ci
+
+# Stage 2: on frontend change
+FROM node:18-alpine AS frontend-builder
+WORKDIR /opt/app
 COPY ./frontend .
+COPY --from=frontend-dependencies /opt/app/node_modules ./node_modules
 RUN npm run build
 
-FROM node:18-slim AS backend-builder
-RUN apt-get update && apt-get install -y openssl
+# Stage 3: on backend dependency change
+FROM node:18-alpine AS backend-dependencies
 WORKDIR /opt/app
 COPY backend/package.json backend/package-lock.json ./
 RUN npm ci
-COPY ./backend .
-RUN npx prisma generate
-RUN npm run build
 
-FROM node:18-slim AS runner
+# Stage 4:on backend change
+FROM node:18-alpine AS backend-builder
+RUN apk add --update openssl
+WORKDIR /opt/app
+COPY ./backend .
+COPY --from=backend-dependencies /opt/app/node_modules ./node_modules
+RUN npx prisma generate
+RUN npm run build  && npm prune --production
+
+# Stage 5: Final image
+FROM node:18-alpine AS runner
 ENV NODE_ENV=production
-RUN apt-get update && apt-get install -y openssl
+RUN apk add --update openssl
+
 WORKDIR /opt/app/frontend
-COPY --from=frontend-builder /opt/app/next.config.js .
 COPY --from=frontend-builder /opt/app/public ./public
-COPY --from=frontend-builder /opt/app/.next ./.next
-COPY --from=frontend-builder /opt/app/node_modules ./node_modules
+# Automatically leverage output traces to reduce image size
+# https://nextjs.org/docs/advanced-features/output-file-tracing
+COPY --from=frontend-builder /opt/app/.next/standalone ./
+COPY --from=frontend-builder /opt/app/.next/static ./.next/static
 
 WORKDIR /opt/app/backend
 COPY --from=backend-builder /opt/app/node_modules ./node_modules
@@ -31,4 +46,5 @@ COPY --from=backend-builder /opt/app/package.json ./
 
 WORKDIR /opt/app
 EXPOSE 3000
-CMD cd frontend && node_modules/.bin/next start & cd backend && npm run prod
+EXPOSE 8080
+CMD node frontend/server.js & cd backend && npm run prod