How to debug NodeJS inside a docker container

It can be tricky to debug a NodeJS application if you haven’t worked with docker for long. Let me save you some time!

The dockerfile I am using:

1. Create a docker-compose.yaml for main configuration:

2. Create a debug-compose.yaml for debug configuration:

3. Add this configuration to your vscode launch.json file:

4. Run:

docker-compose -f docker-compose.yaml -f debug-compose.yaml

Docker will combine docker-compose and debug-compose Overriding the first files configuration with the second. Check docker documentation for details.

5. Go to your vscode debug panel (CTRL + SHIFT + D) select Docker: Attach to Node from the menu and click run, the debugger will break on first line. You can change line 12 of debug-compose.yaml from --inspect-brk to --inspect to turn off breaking right away.

If you are not using docker-compose . You can achieve the same thing by changing the the last line of Dockerfile to CMD ["node", "--inspect=0.0.0.0", "server.js" ] and running:

docker build . docker run -p 9229:9229