Next.js. Required files for docker image

Question

I am creating a Next.js project using Docker, but every time I run docker build, the docker image is 300 MB+. My goal is to reduce the size of the docker image. For this I started using zeit/pkg but it doesn't work properly.

Question:

What files are required in Next.js for docker build? (I see COPY . . in each tutorial)
And how can I reduce the size of the docker image?

I followed this tutorial: https://medium.com/@evenchange4/deploy-a-commercial-next-js-application-with-pkg-and-docker-5c73d4af2ee

Dockerfile:

FROM node:lts-alpine as build-env
WORKDIR /app

COPY . .

RUN yarn install --pure-lockfile --ignore-engines
ENV NODE_ENV=production
RUN yarn run build
RUN yarn run pkg

FROM node:alpine

RUN apk update && \
  apk add --no-cache libstdc++ libgcc ca-certificates && \
  rm -rf /var/cache/apk/*

WORKDIR /app

COPY --from=build-env /app/pkg .

ENV NODE_ENV=production

EXPOSE 8080

CMD ./next-app

package.json:

{
  "name": "next-app",
  "bin": "server.js",
  "pkg": {
    "assets": [
      ".next/**/*"
    ],
    "scripts": [
      ".next/**/*.js"
    ]
  },
  "scripts": {
    "test": "jest",
    "dev": "next",
    "build": "next build",
    "start": "NODE_ENV=production node server.js",
    "pkg": "pkg . -t node13-linux-x64 -o pkg"
  },
  "dependencies": {
    "next": "^9.4.0",
    "react": "^16.13.1",
    "react-dom": "^16.13.1"
  },
  "devDependencies": {
    "pkg": "4.4.8",
    "typescript": "^3.9.2"
  }
}

Answer 1

I know it has been over 5 months since this question was asked, but I was running in the same issue.

I solved it by setting up a multistage build in docker and only copy the required files to run a production nextjs app.

My Dockerfile

# Build the app
FROM node:14-alpine as build
WORKDIR /app

COPY . .
RUN npm ci
RUN npm run build
COPY ./.next ./.next


# Run app
FROM node:14-alpine

# Only copy files required to run the app
COPY --from=build /app/.next ./
COPY --from=build /app/package.json ./
COPY --from=build /app/package-lock.json ./

EXPOSE 3000

# Required for healthcheck defined in docker-compose.yml
# If you don't have a healthcheck that uses curl, don't install it
RUN apk --no-cache add curl

# By adding --production npm's devDependencies are not installed
RUN npm ci --production
RUN ./node_modules/.bin/next telemetry disable

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

USER nextjs
CMD ["npm", "start"]

An excerpt from my package.json

  "dependencies": {
    "next": "^9.5.5",
    "next-compose-plugins": "^2.2.0",
    "react": "^16.12.0",
    "react-dom": "^16.12.0"
  },