使用 Docker 运行 Node 应用程序时出错：db-on-docker@1.0.0 start: `node index.js`

Question

I have developed a Nodejs application with Docker but when I run the application I get the error:

module.js:550
    throw err;
    ^

Error: Cannot find module 'express'
    at Function.Module._resolveFilename (module.js:548:15)
    at Function.Module._load (module.js:475:25)
    at Module.require (module.js:597:17)
    at require (internal/module.js:11:18)
    at Object.<anonymous> (/usr/src/app/index.js:1:81)
    at Module._compile (module.js:653:30)
    at Object.Module._extensions..js (module.js:664:10)
    at Module.load (module.js:566:32)
    at tryModuleLoad (module.js:506:12)
    at Function.Module._load (module.js:498:3)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! db-on-docker@1.0.0 start: `node index.js`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the db-on-docker@1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm WARN Local package.json exists, but node_modules missing, did you mean to install?

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2022-01-30T05_34_13_500Z-debug.log

Following are my files: DockerFile present within web folder:

FROM node:8

WORKDIR /usr/src/app

COPY package*.json ./

RUN npm install

COPY . .

EXPOSE 9000

CMD ["npm","start"]

CMD tail -f /dev/null

Following is my docker-compose.yml file present within my root project folder :

version: '3'

services:
  db:
    container_name: db
    image: mysql:5.7
    volumes:
      - "./data/mysql:/var/lib/mysql:rw"
    environment:
      MYSQL_DATABASE: db
      MYSQL_ROOT_PASSWORD: 123456
      MYSQL_USER: admin
      MYSQL_PASSWORD: 123456
      DATABASE_HOST: localhost
    restart: always

  web:
    container_name: web
    image: node:8
    volumes:
      - ./web:/usr/src/app
    working_dir: /usr/src/app
    depends_on:
      - db
    restart: on-failure
    command: "tail -f /dev/null"
    environment: ["project=${project}", "type=${type}"]

I did the following things:

1. docker-compose build -d to load all images.
2. docker-comoise up -d to bring-up all the images and confirmed the same using docker-compose ps .
3. Then ran the application using the command docker-compose exec web sh -c "project=myproject type=New npm start"

When I run the 3rd step I get the error as provided above. This was working previously when I developed the application. Now I am trying to run the same application in another system but getting this error. Unable to follow what might be wrong.

I have added the express using npm install so I guess its not due to that but due to the line npm ERR. Failed at the db-on-docker@1.0.0 start script. npm ERR. Failed at the db-on-docker@1.0.0 start script. , I tried to install express using npm install --save express , deleted the node_modules folder. Tried the npm install but nothing seems to work for me.

Can someone please let me know what I need to do?

Answer 1

There is one thins missing there in your docker-compose.yml file:

You don't tell docker to build your Dockerfile , instead, just grab the image node:8 from docker registry, but how does docker know that you need to install your packages?

You have to add this block under web service in docker-compose.yml file:

build:
      context: ./web

One more thing to mention is that, you're overriding the default command that you declared in Dockerfile , you can remove this line from docker-compose.yml file

command: "tail -f /dev/null"

Honestly, I don't know why you need this here.

You can also try to remove this instruction from Dockerfile :

CMD tail -f /dev/null

I think npm start is enough

Note : npm start requires that you define the entry point in your package.json file, otherwise, you will get an error

One lat thing and back you the error you've mentioned herewith in your question:

The reason is because the container can't find express module installed inside the image you're using node:8 in this case, because you just use the image and map your project directory to the container without installing the dependencies.