Debug webpack-dev-server application inside Docker container

Question

I'm using webpack-dev-server to run an Nestjs application inside a Docker container. All is up and running, but I can't debug the application from my VS Code instance. I'm trying to expose the 9229 port using this configuration on the webpack.config.js :

devServer: {
  host: '0.0.0.0',
  port: 9229,
},

When I run netstat -l inside the container I can see that node is not listening the 9229 port:

I'm exposing the port 9229 in the Dockerfile and docker-compose files. The Dockerfile:

FROM node:12.16.1-alpine
WORKDIR /usr/src/app
COPY package.json yarn.lock ./
RUN yarn
COPY . .
EXPOSE 3000
EXPOSE 9229
CMD [ "yarn", "run", "start:debug"]

And the docker-compose.yml file:

version: '3.7'
services:
    open-tuna-api:
        image: opentunaapi
        ports:
            - 3000:3000
            - 9229:9229
        volumes: 
            - ./dist:/usr/src/app/dist
            - ./:/usr/src/app
        networks:
            - open-tuna-network
        expose: 
            - 9229
networks:
    open-tuna-network:

And this is the script I'm using to run the application:

"start:debug": "webpack --config webpack.config.js && node --inspect=0.0.0.0:9229 node_modules/webpack-dev-server/bin/webpack-dev-server.js",

My launch configuration is as follow:

{
    "name": "Attach",
    "preLaunchTask": "compose-up",
    "stopOnEntry": true,
    "type": "node",
    "request": "attach",
    "port": 9229,
    "cwd": "${workspaceFolder}", // the root where everything is based on
    "localRoot": "${workspaceFolder}", // root of all server files
    "remoteRoot": "/usr/src/app", // workspace path which was set in the dockerfile
    "outFiles": ["${workspaceFolder}/dist/**/*.js"], // all compiled JavaScript files
    "protocol": "inspector",
    "restart": true,
    "sourceMaps": true,
    "trace": "verbose",
    "address": "0.0.0.0",
    "skipFiles": [
        "<node_internals>/**"
    ],
}

And when I run this configuration with the container up and running I'm receiving a message saying that VS Code cannot connect to the process.

So, my question is: is there a way to debug JavaScript / TypeScript app running on webpack-dev-server inside a Docker container? What is wrong in my environment?

Thanks for the help.

EDIT

Apparently my issue has no relation with Docker, since I can reproduce it outside of the container.

Answer 1

Have a look at your config and make sure you include the program field. And point it to the right file under node_modules .

"program": "${workspaceRoot}/node_modules/webpack-dev-server/bin/webpack-dev-server.js"

That should get you going.

If you want more insight into this, there's a longer conversation that you might find useful - check out this comment on the main webpack-dev-server GitHub repo.