How to fix docker container running 'cannot find module' error?

Question

I am new to docker and trying to move my MERRN stack application to AWS. I want to dockerize it before I move it. However, when I followed this online tutorial at Medium - Docker with MERN stack I get to the part with starting up my docker image with docker run -p 5000:5000 -d backend and I get an error in VS code. I am not sure what this error means but I theorize it has to do with my folder management.

I will attach a snippet of my folder structure as well as the docker file I used. So my main problem is I am trying to get everything setup but this issue is hindering my progress. So any help would be appreciated. Thanks

DockerFile:

FROM node:10.19.0
# Create app directory
WORKDIR /usr/src/app
# A wildcard is used to ensure both package.json AND package-lock.json are copied
COPY package*.json ./
# Bundle app source
COPY . .
# Install app dependencies
RUN npm install
EXPOSE 5000
CMD [ "npm", "start" ]

Error:

> exodus@1.0.0 start /usr/src/app

> node server


internal/modules/cjs/loader.js:638

throw err;

^


Error: Cannot find module './routes/api/Email'

at Function.Module._resolveFilename (internal/modules/cjs/loader.js:636:15)

at Function.Module._load (internal/modules/cjs/loader.js:562:25)

at Module.require (internal/modules/cjs/loader.js:692:17)

at require (internal/modules/cjs/helpers.js:25:18)

at Object.<anonymous> (/usr/src/app/server.js:24:19)

at Module._compile (internal/modules/cjs/loader.js:778:30)

at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)

at Module.load (internal/modules/cjs/loader.js:653:32)

at tryModuleLoad (internal/modules/cjs/loader.js:593:12)

at Function.Module._load (internal/modules/cjs/loader.js:585:3)

at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)

at startup (internal/bootstrap/node.js:283:19)

at bootstrapNodeJSCore (internal/bootstrap/node.js:623:3)

npm ERR! code ELIFECYCLE

npm ERR! errno 1

npm ERR! exodus@1.0.0 start: `node server`

npm ERR! Exit status 1



npm ERR!

npm ERR! Failed at the exodus@1.0.0 start script.

npm ERR! This is probably not a problem with npm. There is likely additional logging output above.


npm ERR! A complete log of this run can be found in:

npm ERR! /root/.npm/_logs/2020-10-28T20_13_53_160Z-debug.log

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Answer 1

Your Dockerfile seems ok and your project structure, too. I assume that the docker image is faulty for some reason and missing the files.

Can you try to build the image again? Is the COPY step executed correctly?

// Make sure to execute this in the project root.
docker build -t backend .

If the error persists, log into the docker container using bash or sh and try to manually start the node server with npm start :

docker run -p 5000:5000 -d backend /bin/bash
or
docker run -p 5000:5000 -d backend /bin/sh

Logging into the docker container will also help to investigate if eg some files were not transferred.