Docker "module" error on express-based node app

Bruno Peixoto 0
Viewed 22

I learn about node-js and Docker. Since the beginning of this journey, I have developed incrementally this library. I can:

  1. Write a NodeJS app;
  2. Extend it to an express web app;
  3. Write a docker-compose.yml;
  4. Write a DockerFile;

So far, so good. Since we want to production-publish it, we run the command docker build -t IMAGE_NAME . && docker-compose up. The following error pops out:

Starting nodejs ... done
Attaching to nodejs
nodejs    | [nodemon] 2.0.15
nodejs    | [nodemon] to restart at any time, enter `rs`
nodejs    | [nodemon] watching path(s): *.*
nodejs    | [nodemon] watching extensions: js,mjs,json
nodejs    | [nodemon] starting `node app.js ./src/index.js`
nodejs    | /home/node/app/src/index.js:2
nodejs    | import express from 'express';
nodejs    |        ^^^^^^^
nodejs    | 
nodejs    | SyntaxError: Unexpected identifier
nodejs    |     at Module._compile (internal/modules/cjs/loader.js:723:23)
nodejs    |     at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
nodejs    |     at Module.load (internal/modules/cjs/loader.js:653:32)
nodejs    |     at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
nodejs    |     at Function.Module._load (internal/modules/cjs/loader.js:585:3)
nodejs    |     at Function.Module.runMain (internal/modules/cjs/loader.js:831:12)
nodejs    |     at startup (internal/bootstrap/node.js:283:19)
nodejs    |     at bootstrapNodeJSCore (internal/bootstrap/node.js:623:3)

It seems a silly mistake I make, but at this point, I am still very novice to notice it. I thank you in advance for any help.

node.js
1 Answers

This looks like an issue with your Dockerfile.

FROM node:10-alpine

RUN npm install

RUN mkdir -p /home/node/app/node_modules && chown -R node:node /home/node/app
WORKDIR /home/node/app

You're running npm install before setting your WORKDIR. Have you tried running echo $PWD?

FROM node:10-alpine

RUN echo $PWD

You probably just need to set your WORKDIR first, since you probably want to run npm install in there.

Your volumes look like they might cause some issues too:

    volumes:
      - .:/home/node/app
      - node_modules:/home/node/app/node_modules

You're creating a volume that will sync the node_modules you have installed into the container. This isn't what we want, because we want to set as much as we can inside the Dockerfile.

    volumes:
      - .:/home/node/app
      - /home/node/app/node_modules

Doing this will prevent node_modules from being sync'd, which would overwrite anything you had installed by including RUN npm install in your Dockerfile.

If you make these changes, you should be alright.

danieldaugherty0
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