First, change the output method in the next.config.js file to use the standalone mode. This will reduce the size of the image by removing unnecessary files/dependencies.

const nextConfig = {
  output: "standalone",
  ...
};

Next, create a custom Dockerfile to build the image. Go over the steps to make sure it matches your use case.

FROM node:21-alpine AS builder
WORKDIR /app

# Copy only the files needed to install dependencies
COPY package.json pnpm-lock.yaml* ./

# Install dependencies with the preferred package manager
RUN npm i -g pnpm && pnpm i --frozen-lockfile;

# Copy the rest of the files
COPY . .

# Consume ENV variables and build the project
ARG NEXT_PUBLIC_API_URL

RUN pnpm run build



FROM node:21-alpine AS runner
WORKDIR /app
ENV NODE_ENV production

# Copy public assets
COPY --from=builder /app/public ./public
# Automatically leverage output traces to reduce image size
# https://nextjs.org/docs/advanced-features/output-file-tracing
COPY --from=builder /app/.next/standalone ./
COPY --from=builder /app/.next/static ./.next/static
EXPOSE $PORT

CMD ["node", "server.js"]