Next.js Dockerfile using npm instead of yarn

The example Dockerfile provided on the Next.js documentation only shows how to build for yarn. Below is a small adjustment to the original file to work with npm instead.

This is useful if you have a package.lock.json instead of a yarn.lock file, because your project uses npm install rather than yarn install.

# Install dependencies only when needed
FROM node:alpine AS deps
# Check https://github.com/nodejs/docker-node/tree/b4117f9333da4138b03a546ec926ef50a31506c3#nodealpine to understand why libc6-compat might be needed.
RUN apk add --no-cache libc6-compat
WORKDIR /app
# COPY package.json yarn.lock ./
COPY package.json package-lock.json ./
# RUN yarn install --frozen-lockfile
RUN npm ci

# Rebuild the source code only when needed
FROM node:alpine AS builder
WORKDIR /app
COPY . .
COPY --from=deps /app/node_modules ./node_modules
# RUN yarn build && yarn install --production --ignore-scripts --prefer-offline
RUN npm run build && npm install --production --ignore-scripts --prefer-offline

# Production image, copy all the files and run next
FROM node:alpine AS runner
WORKDIR /app

ENV NODE_ENV production

RUN addgroup -g 1001 -S nodejs
RUN adduser -S nextjs -u 1001

# You only need to copy next.config.js if you are NOT using the default configuration
# COPY --from=builder /app/next.config.js ./
COPY --from=builder /app/public ./public
COPY --from=builder --chown=nextjs:nodejs /app/.next ./.next
COPY --from=builder /app/node_modules ./node_modules
COPY --from=builder /app/package.json ./package.json

USER nextjs

EXPOSE 3000

# Next.js collects completely anonymous telemetry data about general usage.
# Learn more here: https://nextjs.org/telemetry
# Uncomment the following line in case you want to disable telemetry.
ENV NEXT_TELEMETRY_DISABLED 1

# CMD ["yarn", "start"]
CMD ["npm", "run", "start"]