Cannot find module for a node js app running in a docker compose environment

Question

I am sorry for my very newbie question, but I am having a terrible day figuring out this error, I have an Express app and I am trying to run it in docker compose. I've used this Dockerfile:

FROM mhart/alpine-node
RUN mkdir -p /usr/src/app
RUN chmod -R 777 /usr/src/app
WORKDIR /usr/src/app
RUN npm install node-gyp -g
RUN npm install nodemon -g
ENV NODE_ENV development
EXPOSE 3000

And this portion of my docker-compose file:

backend:
    mem_limit: 100m
    build:
      context: .
      dockerfile: dockerfiles/node/Dockerfile
    command: npm start
    depends_on:
      - mongo
      - elasticsearch
    volumes:
      - ./backend/:/usr/src/app
    ports:
      - 3000:3000
    links:
      - "mongo:mongo"
      - "elasticsearch:elasticsearch"

When I do docker-compose up, I get this error:

backend_1        | npm info it worked if it ends with ok
backend_1        | npm info using npm@3.10.10
backend_1        | npm info using node@v6.9.5
backend_1        | npm info lifecycle service-designer@1.0.0~prestart: service-designer@1.0.0
backend_1        | npm info lifecycle service-designer@1.0.0~start: service-designer@1.0.0
backend_1        | 
backend_1        | > service-designer@1.0.0 start /usr/src/app
backend_1        | > nodemon index.js
backend_1        | 
backend_1        | [nodemon] 1.11.0
backend_1        | [nodemon] to restart at any time, enter `rs`
backend_1        | [nodemon] watching: *.*
backend_1        | [nodemon] starting `node index.js`
backend_1        | module.js:471
backend_1        |     throw err;
backend_1        |     ^
backend_1        | 
backend_1        | Error: Cannot find module 'dotenv'
backend_1        |     at Function.Module._resolveFilename (module.js:469:15)
backend_1        |     at Function.Module._load (module.js:417:25)
backend_1        |     at Module.require (module.js:497:17)
backend_1        |     at require (internal/module.js:20:19)
backend_1        |     at Object.<anonymous> (/usr/src/app/index.js:1:63)
backend_1        |     at Module._compile (module.js:570:32)
backend_1        |     at Object.Module._extensions..js (module.js:579:10)
backend_1        |     at Module.load (module.js:487:32)
backend_1        |     at tryModuleLoad (module.js:446:12)
backend_1        |     at Function.Module._load (module.js:438:3)
backend_1        | [nodemon] app crashed - waiting for file changes before starting...

If I do ls -al in the backend container, I get a full list of my backend app folder content, but it sounds like node_modules dependencies are not recognized.

Answer 1

You need to install the dependencies in the container, which is missing from your Dockerfile.

The common way is to create a Dockerfile that is already aware of your application, and make it copy your package.json file and perform an npm install .

This allows your container to find all your code dependencies when you later run your application.

See and example here: https://nodejs.org/en/docs/guides/nodejs-docker-webapp/

The sample Dockerfile :

FROM node:boron

# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

# Install app dependencies
COPY package.json /usr/src/app/
RUN npm install

# Bundle app source
COPY . /usr/src/app

EXPOSE 8080
CMD [ "npm", "start" ]

You may need to adapt paths for the COPY command, of course.

Answer 2

If your Dockerfile and package.json files are correct and still have the issue:

1. Make sure you've rebuilt your container images.

2. Try

docker-compose down -v

before starting the containers again with docker-compose up .

This removes all volumes.

Answer 3

I also had the same issue when I run docker-compose up .

Issue resolved by running docker-compose up --build instead of docker-compose up .

Answer 4

After adding npm install to the Dockerfile, add node_modules to volumes

volumes:
      - ./backend/:/usr/src/app
      - /usr/src/app/node_modules

Answer 5

It happened to me because I had the file names in upper case.

what is recommended is rename files to lowercase

delete the dist folder

run again

npm run start:dev

to generate a new dist folder.

again run the

docker build -t <name> .

Answer 6

If your Dockerfiles and compose file are correct then you should do this docker-compose build --no-cache Then you can do docker-compose up again. This resolved the issue for me.

Answer 7

我有同样的问题，你需要做的只是运行npm i来安装所有依赖项，然后重建，问题解决了

Answer 8

Make sure that in package.json in the scripts object the npm start has the nodemon command to run your application

Example: if your application is served by the server.js file

"scripts": {
    "start": "nodemon server.js",
}