Node.js Error: Cannot find module (local file) - node.js

Question

I am following Node.js's "Intro to Docker" tutorial and, when I run npm start, the project works. When I run docker run (options), the build is generated, but I'll find the error below in the logs. The project is bare-bones, simple, and straight-forward, I'm not sure what I'm missing here. I've gotten a very similar error in production earlier (to Heroku, without Docker), where local runs look good and live deploys get a similar error.
I'm not sure if I'm using something outdated, but I updated npm, docker, and am not sure what else could be.
Any help is appreciated!
Error:
internal/modules/cjs/loader.js:969
throw err;
^
Error: Cannot find module '/usr/src/app/server.js'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:966:15)
at Function.Module._load (internal/modules/cjs/loader.js:842:27)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
at internal/main/run_main_module.js:17:47 {
code: 'MODULE_NOT_FOUND',
requireStack: []
}
Directory:
package.json:
{
"name": "SampleProject",
"version": "1.0.0",
"description": "Node.js on Docker",
"author": "First Last <first.last#example.com>",
"main": "server.js",
"scripts": {
"start": "node server.js",
"dock": "docker run -p 1234:1234 -d <My>/<Info>"
},
"dependencies": {
"core-util-is": "^1.0.2",
"express": "^4.17.1"
}
}
Dockerfile
# I'm using Node.js -> Import it's image
FROM node:12
# Create app directory
WORKDIR /usr/src/app
# Install app dependencies
# A wildcard is used to ensure both package.json AND package-lock.json are copied
# where available (npm#5+)
COPY package*.json ./
RUN npm install
# If you are building your code for production
# RUN npm ci --only=production
# Run on port 1234
EXPOSE 1234
CMD [ "node", "server.js" ]
server.js
'use strict';
const express = require('express');
// Constants
const PORT = 1234;
const HOST = '0.0.0.0';
// App
const app = express();
app.get('/', (req, res) => {
res.send('Hello World');
});
app.listen(PORT, HOST);
console.log(`Running on http://${HOST}:${PORT}`);
Run:
npm run dock
Note:
I've also cleaned out the project by running the following:
rm -rf node_modules package-lock.json && npm install && npm start
RESOLVED:
Dockerfile
# I'm using Node.js -> Import it's image
FROM node:12
# Create app directory
WORKDIR /usr/src/app
# Install app dependencies
# A wildcard is used to ensure both package.json AND package-lock.json are copied
# where available (npm#5+)
COPY package*.json ./
RUN npm install
# If you are building your code for production
# RUN npm ci --only=production
# * BEGIN SOLUTION *
# Bundle app source
COPY . .
# * END SOLUTION *
# Run on port 1234
EXPOSE 1234
CMD [ "node", "server.js" ]

Answer 1

I think you are missing the following important part, should be placed after you have RUN npm install:
To bundle your app's source code inside the docker image, use the COPY instruction:
# Bundle app source
COPY . .
And to force the execution of each step in the Dockerfile,
docker build --no-cache