How to solve Node.js Error: Cannot find Module? - node.js

Question

When I start a dockerized Node.js testapp with
sudo docker-compose up
I get the following error:
Starting testapp_web_1 ... done
Attaching to testapp_web_1
web_1 |
web_1 | > testapp#0.0.1 start /usr/app
web_1 | > node index.js
web_1 |
web_1 | internal/modules/cjs/loader.js:613
web_1 | throw err;
web_1 | ^
web_1 |
web_1 | Error: Cannot find module 'mongodb'
web_1 | Require stack:
web_1 | - /usr/app/index.js
web_1 | at Function.Module._resolveFilename (internal/modules/cjs/loader.js:610:15)
web_1 | at Function.Module._load (internal/modules/cjs/loader.js:526:27)
web_1 | at Module.require (internal/modules/cjs/loader.js:666:19)
web_1 | at require (internal/modules/cjs/helpers.js:16:16)
web_1 | at Object.<anonymous> (/usr/app/index.js:4:21)
web_1 | at Module._compile (internal/modules/cjs/loader.js:759:30)
web_1 | at Object.Module._extensions..js (internal/modules/cjs/loader.js:770:10)
web_1 | at Module.load (internal/modules/cjs/loader.js:628:32)
web_1 | at Function.Module._load (internal/modules/cjs/loader.js:555:12)
web_1 | at Function.Module.runMain (internal/modules/cjs/loader.js:826:10)
web_1 | npm ERR! code ELIFECYCLE
web_1 | npm ERR! errno 1
web_1 | npm ERR! testapp#0.0.1 start: `node index.js`
web_1 | npm ERR! Exit status 1
web_1 | npm ERR!
web_1 | npm ERR! Failed at the testapp#0.0.1 start script.
web_1 | npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
web_1 |
web_1 | npm ERR! A complete log of this run can be found in:
web_1 | npm ERR! /root/.npm/_logs/2019-05-04T15_34_04_615Z-debug.log
testapp_web_1 exited with code 1
The project structur is as follows
- testapp
--- docker-compose.yml
--- dockerfile
--- src
----- index.js
----- package.json
index.js
'use strict';
const MongoClient = require('mongodb').MongoClient;
const express = require('express');
// Constants
const PORT = 8080;
// App
const app = express();
app.get('/', (req, res) => {
res.send('Hello world\n');
});
app.listen(PORT);
console.log(`Running on Port:${PORT}`);
package.json
{
"name": "testapp",
"version": "0.0.1",
"description": "Testapp",
"author": "hi there",
"main": "index.js",
"scripts": {
"start": "node index.js"
},
"dependencies": {
"express": "^4.16.4",
"mongodb": "^3.2.3"
}
}
dockerfile
FROM node:12-alpine
WORKDIR /usr/app
COPY package*.json ./
RUN npm install
COPY . .
EXPOSE 8080
docker-compose.yml
version: '3'
services:
web:
build: .
command: npm start
volumes:
- ./src:/usr/app/
- /usr/app/node_modules
ports:
- 80:8080
I have alread read this stackoverflow thread but I couldn't solve this issue. I'm getting this error no matter what module I'm trying to use: mongodb, spdy, etc. Locally without docker the testapp is working. But I don't know what I'm doing wrong with docker. Can anyone help me?

Answer 1

Have volume folder mapping for node_modules and ensure it has mongo folder copied / created
version: '3'
services:
web:
build: .
command: npm start
volumes:
- ./src:/usr/app/
- ./src/node_modules:/usr/app/node_modules
ports:
- 80:8080
Ref:https://morioh.com/p/42531a398049/containerizing-a-node-js-application-for-development-with-docker-compose

Answer 2

You need to drop & rebuild the anonymous volume holding the node_modules for the updates to package.json to take effect.
docker-compose rm -v
# then:
docker-compose build
docker-compose up
You will only have to do this for changes to node_modules, since the other volume is linked to your ./src/, and will reflect changes on the host.