[SOLVED] I am getting error while converting my next js project to docker

I am getting error while converting my next js project to docker

I'm trying to convert my Next js project to Docker. The Dockerfile I got from the next js github page worked fine for me and I got a build successfully.

# Install dependencies only when needed
FROM node:16-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 ./
RUN yarn install --frozen-lockfile

# Rebuild the source code only when needed
FROM node:16-alpine AS builder
WORKDIR /app
COPY --from=deps /app/node_modules ./node_modules
COPY . .
RUN yarn build

# Production image, copy all the files and run next
FROM node:16-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 /app/package.json ./package.json

# Automatically leverage output traces to reduce image size
# https://nextjs.org/docs/advanced-features/output-file-tracing
# COPY --from=builder --chown=nextjs:nodejs /app/.next/standalone ./
COPY --from=builder --chown=nextjs:nodejs /app/.next/static ./.next/static

USER nextjs

EXPOSE 3000

ENV PORT 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 ["node", "server.js"]

I wrote this later.

docker run -p 3000:3000 imagename

Then I faced such error and I can't solve it.

node:internal/modules/cjs/loader:936
  throw err;
  ^

Error: Cannot find module '/app/server.js'
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:933:15)
    at Function.Module._load (node:internal/modules/cjs/loader:778:27)
    at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:81:12)
    at node:internal/main/run_main_module:17:47 {
  code: 'MODULE_NOT_FOUND',
  requireStack: []
}

I searched a lot on the internet but couldn't find much. What do you think I should do?

Solution

Ensure that you're copying all files from the example. In this case you need to ensure you have added or customized next.config.js with this:

module.exports = {
  output: 'standalone'
}

You'll notice the file is also defined in the examples: https://github.com/vercel/next.js/blob/canary/examples/with-docker/next.config.js