Debugging NodeJS Azure function in a docker container from VS Code

I cannot get remote debugging up & running for my NodeJS Azure function in a docker container.

Setup:

I followed the tutorial from documentation and created a sample HTTP triggered function

func init --worker-runtime node --language typescript --docker
func new --name HttpExample --template "HTTP trigger" --authlevel anonymous

It created the following folder structure

And the generated docker file

FROM mcr.microsoft.com/azure-functions/node:4-node18

ENV AzureWebJobsScriptRoot=/home/site/wwwroot \
    AzureFunctionsJobHost__Logging__Console__IsEnabled=true

COPY . /home/site/wwwroot

RUN cd /home/site/wwwroot && \
    npm install && \
    npm run build

I started the container with the turned-on Node debugger

docker run -p 8080:80 -p 9233:9233 -e NODE_OPTIONS=--inspect=0.0.0.0:9233 -it af-docker

From the container output, I can see that the debugger is listening on port 9233

info: Host.Function.Console[0]
  Debugger listening on ws://0.0.0.0:9233/77214a10-aeb3-47e0-ac5a-2dcd4f021008
info: Host.Function.Console[0]
  For help, see: https://nodejs.org/en/docs/inspector

So I edited the launch.json file to add support for remote debugging

{
    "configurations": [
    {
        "type": "node",
        "request": "attach",
        "name": "Docker: Attach to Node",
        "remoteRoot": "/site/wwwroot/dist/src/functions",
        "localRoot": "${workspaceRoot}\\src\\functions",
        "port": 9233,
        "address": "localhost",
        "sourceMaps": true,
        }
    ]
}

Result:

When I run the debugger (F5), I can see from the container output that the debugger is attached

info: Host.Function.Console[0]
  Debugger attached.

However, I get the following error in the debug console and breakpoints are not hit/binded

LanguageWorkerConsoleLogWorker b62c4a73-8509-4a3f-a496-cca18cb56bb0 connecting on 127.0.0.1:42681
worker-bundle.js:2
Could not read source map for file:///azure-functions-host/workers/node/dist/src/nodejsWorker.js: ENOENT: no such file or directory, open 'C:\azure-functions-host\workers\node\dist\src\nodejsWorker.js.map'
Could not read source map for file:///home/site/wwwroot/dist/src/functions/HttpExample.js: ENOENT: no such file or directory, open 'C:\home\site\wwwroot\dist\src\functions\HttpExample.js.map'

Both paths are invalid (C:\azure-functions-host\**) and (C:\home\site\**) and do not exist on the local machine. I suppose there is some misconfiguration in the launch.json file, but I cannot figure out what is wrong.

Could not read source map for file:///azure-functions-host/workers/node/dist/src/nodejsWorker.js: ENOENT: no such file or directory, open 'C:\azure-functions-host\workers\node\dist\src\nodejsWorker.js.map' Could not read source map for file:///home/site/wwwroot/dist/src/functions/HttpExample.js: ENOENT: no such file or directory, open 'C:\home\site\wwwroot\dist\src\functions\HttpExample.js.map'

You are getting this error because debugger is trying to look for dist\src\functions folder in your folder structure.

To generate dist folder, run the commands in the following order-

 1. func init --worker-runtime node --language typescript --docker
 2. func new --name HttpExample --template "HTTP trigger" --authlevel anonymous
 3. npm install
 4. npm start

You will be able to see below folder structure.

Then I made the same changes which you did in launch.json file.

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "Docker: Attach to Node",
            "type": "node",
            "request": "attach",
            "remoteRoot": "/site/wwwroot/dist/src/functions",
            "localRoot": "${workspaceRoot}\\src\\functions",
            "port": 9233,
            "address": "localhost",
            "sourceMaps": true,
        }
    ]
}

I started the debugger and got the expected output.