Unable to debug Azure Functions Core Tools in VSCode

Question

I am currently having trouble to debug my Azure Functions Core Tools in VS Code. I am using the npm package azure-functions-core-tools@2. As i read on many resources func host start / func start should always start the node process in with --inspect=9229. As you can see this is not the case in my setup:

[4/30/19 4:51:25 AM] Starting language worker process:node  "/usr/lib/node_modules/azure-functions-core-tools/bin/workers/node/dist/src/nodejsWorker.js" --host 127.0.0.1 --port 50426 --workerId 3e909143-72a3-4779-99c7-376ab3aba92b --requestId 656a9413-e705-4db8-b09f-da44fb1f991d --grpcMaxMessageLength 134217728
[4/30/19 4:51:25 AM] node process with Id=92 started
[4/30/19 4:51:25 AM] Generating 1 job function(s)
[...]
[4/30/19 4:51:25 AM] Job host started
Hosting environment: Production

Also all attempts of changing the hosting environment failed. I tried to add FUNCTIONS_CORETOOLS_ENVIRONMENT to my local configuration, resulting in an error:

An item with the same key has already been added. Key: FUNCTIONS_CORETOOLS_ENVIRONMENT

I tried to add several environment variables in my launch and task settings, using --debug, changing project settings. Nothing works.

I am currently running this on the Windows Subsystem for Linux (WSL) and except this it works really well.

Anyone has a clue on what i am doing wrong here?

Answer 1

I don't think debug is enabled by default. You will have to set the language worker arguments for this to work as documented.

1. In local.settings.json

   To debug locally, add "languageWorkers:node:arguments": "--inspect=5858" under Values in your local.settings.json file and attach a debugger to port 5858.

2. With func CLI
   You could set this by using the --language-worker argument

func host start --language-worker -- --inspect=5858

3. In VS Code
   If you are developing using VS Code and the Azure Functions extension, the --inspect is added automatically as the corresponding environment variable is set in .vscode/tasks.json

{
  "version": "2.0.0",
  "tasks": [
    {
      "label": "runFunctionsHost",
      "type": "shell",
      "command": "func host start",
      "isBackground": true,
      "presentation": {
        "reveal": "always"
      },
      "problemMatcher": "$func-watch",
      "options": {
        "env": {
          "languageWorkers__node__arguments": "--inspect=5858"
        }
      },
      "dependsOn": "installExtensions"
    },
    {
      "label": "installExtensions",
      "command": "func extensions install",
      "type": "shell",
      "presentation": {
        "reveal": "always"
      }
    }
  ]
}

You could also set this environment variable directly if you'd like instead of adding it in local.settings.json too.