VSCode Newbie: Remote Jest/Node debugging through Docker

Here a shot of my solution, which comes mostly from your same question. Thank you for asking :)

First start jest in watch mode (--watchAll), so the process stays alive. (In the snippet I assume a backend container is running via docker-compose with port 9229 exposed on the host)

docker-compose exec backend \  node --inspect=0.0.0.0:9229 -r tsconfig-paths/register -r ts-node/register \  node_modules/.bin/jest --watchAll --runInBand 

Now in VSCode .vscode/launch.json config add a config to attach to the running process. Note: ensure remoteRoot fit your setup.

{  // Use IntelliSense to learn about possible attributes.  // Hover to view descriptions of existing attributes.  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387  "version": "0.2.0",  "configurations": [    {        "type": "node",        "request": "attach",        "name": "Docker: Debug tests",        "address": "127.0.0.1",        "port": 9229,        "trace": true,        "restart": true,        "timeout": 10000,        "localRoot": "${workspaceFolder}",        "remoteRoot": "/app",        "outFiles": [            "${workspaceFolder}/dist/**/*.js"        ],        "disableOptimisticBPs": true,                    "internalConsoleOptions": "neverOpen",        "continueOnAttach": true,    }]}

From here on I have been able to develop and debug properly my code.

This is my launch.json configuration for debugging Jest tests with Docker.

{  // Use IntelliSense to learn about possible attributes.  // Hover to view descriptions of existing attributes.  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387  "version": "0.2.0",  "configurations": [    {      "type": "node",      "name": "Docker: Jest Tests",      "request": "launch",      "program": "${workspaceFolder}/node_modules/.bin/jest",      "args": [        "--runInBand"      ],      "cwd": "${workspaceFolder}",      "console": "integratedTerminal",      "internalConsoleOptions": "neverOpen",      "disableOptimisticBPs": true,      "windows": {        "program": "${workspaceFolder}/node_modules/jest/bin/jest",      },      "protocol": "inspector"    }  ]}

The idea is start the docker-compose includes a database (Postgres, MongoDB, etc ...) and an api app before run and debug thru VSCode.

Most of a day later, got it.

VSCode launch.json

{  "type": "node",  "name": "docker-jest",  "request": "attach",  "address": "0.0.0.0",  "port": 9229,  "localRoot": "${workspaceFolder}",  "remoteRoot": "/app", // Will depend on your setup  "skipFiles": [    "<node_internals>/**/*.js",    "${workspaceFolder}/node_modules/**/*.js"  ],  "internalConsoleOptions": "neverOpen",  "presentation": {    "reveal": "silent"  }},

Ensure your docker container is running with port 9229 open. I used tail -d /dev/null to keep mine running. I wont go into details of a docker setup since there is plenty of online resources on the topic.

Then enter the docker container

$ docker exec -it container_name /bin/bash

And run

$ node --inspect-brk=0.0.0.0:9229 --nolazy -r ./node_modules/ts-node/register ./node_modules/jest/bin/jest.js --config=./jest-config.json --runInBand

The --runInBand flag is key for this to work.

--runInBand causes all tests to be run in the parent process rather than child processes.

You should see something like

root@7a0ba832e7f9:/app# node --inspect-brk=0.0.0.0:9229 --nolazy -r ./node_modules/ts-node/register ./node_modules/jest/bin/jest.js --config=./jest-config.json --runInBandDebugger listening on ws://0.0.0.0:9229/267bfe8c-dfa8-45e0-a86c-abcadbd97beaFor help, see: https://nodejs.org/en/docs/inspector

Set breakpoints in your Jest .spec.ts files and execute the docker-jest debugger.

If you are continuing to have issues, ensure your app isn't already running in debug mode on the same port. The tests will continue executing with only a brief pause showing the following;

Starting inspector on 0.0.0.0:9229 failed: address already in use

If this happens, just change the debug port used in the node command and launch.json to something else and open the docker port.