Debug support for multiple Docker nodes in vscode-CodePudding

I have a node.js project using Docker that I am trying to debug in Visual Studio Code. I am able to debug the project if one node is deployed using docker-compose up, but if I try to deploy multiple replicas using docker-compose up --scale node=3 I run into the following error:

Bind for 0.0.0.0:9229 failed: port is already allocated

This error is occurring since there are multiple nodes all trying to attach to port 9229. Is there any way to dynamically allocate a port range for debugging instead?

My docker-compose file:

version: '3'
services:
  node:
    env_file: .env
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000" 
      - "9229:9229"
    restart: always
    volumes:
      - .:/home/node/app
      - /home/node/app/node_modules
    environment:
      VIRTUAL_HOST: node.local
      NODE_ENV: development
      VIRTUAL_PORT: 3000

.vscode/launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Docker: Attach to Node",
      "type": "node",
      "request": "attach",
      "restart": true,
      "port": 9229,
      "address": "0.0.0.0",
      "localRoot": "${workspaceFolder}",
      "remoteRoot": "/home/node/app",
      "protocol": "inspector"
    }
  ]
}

Snippet from package.json

{
  "scripts": {
    "start": "node src/index.js",
    "dev": "nodemon --inspect=0.0.0.0:9229 -L src/index.js"
  }
}

CodePudding user response：

One option is to treat port 9229 the same way you treat port 3000:

version: '3'
services:
  node:
    env_file: .env
    build:
      context: .
      dockerfile: Dockerfile
    ports:
      - "3000" 
      - "9229"
    restart: always
    volumes:
      - .:/home/node/app
      - /home/node/app/node_modules
    environment:
      VIRTUAL_HOST: node.local
      NODE_ENV: development
      VIRTUAL_PORT: 3000

When you don't specify a host port, Docker will select a random port on the host; you can see these in docker ps:

CONTAINER ID   ...   STATUS          PORTS                                                                                                NAMES
404f6b766136   ...   Up 2 seconds    8080/tcp, 0.0.0.0:49163->3000/tcp, :::49163->3000/tcp, 0.0.0.0:49162->9229/tcp, :::49162->9229/tcp   example_node_3
7e16271b1dea   ...   Up 2 seconds    8080/tcp, 0.0.0.0:49161->3000/tcp, :::49161->3000/tcp, 0.0.0.0:49160->9229/tcp, :::49160->9229/tcp   example_node_2
1117a0762bdf   ...   Up 11 seconds   8080/tcp, 0.0.0.0:49159->3000/tcp, :::49159->3000/tcp, 0.0.0.0:49158->9229/tcp, :::49158->9229/tcp   example_node_1

From the above docker ps output, we can see that if we want to reach port 9229 on container example_node_1, we need to use port 49158. If we want example_node_2, we need port 49160, etc.

That may be all you need.