Functions debugging in VS Code

Question

From VS Code integrated terminal I run firebase serve --only functions,hosting then in the debug tab I created the default launch.json:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "node",
      "request": "launch",
      "name": "Launch Program",
      "program": "${file}"
    }
  ]
}

I want to debug the server side (functions/index.js) not the client side.

I've tried some configuration from https://code.visualstudio.com/docs/nodejs/nodejs-debugging with no luck.

How to debug Firebase functions in VS Code?

Solution 1

Update: May 2021

It's now possible to debug (put breakpoints) firebase functions running locally on VSCode.

1. update firebase-tools to atleast v7.11.0 npm i -g firebase-tools
2. add below to launch.json:

    {
      "version": "0.2.0",
      "configurations": [
        {
          "type": "node",
          "request": "attach",
          "name": "Attach",
          "port": 9229,
          "restart": true,
          "skipFiles": ["<node_internals>/**"]
        }
      ]
    }

3. run the emulator: firebase emulators:start --inspect-functions
4. run the vscode debugger with attach option.
5. put breakpoint in a cloud function.
6. call that function (something like http://localhost:5001/your_project/us-central1/helloWorld). Breakpoint should hit.

note: Support for PubSub/scheduled functions is still not implemented. Upvote this issue: https://github.com/firebase/firebase-tools/issues/2034

note: if you're testing functions from local firebase hosting setup, then you need to point your hosting functions to local server instead of cloud server. see here https://stackoverflow.com/a/59381328/3073272

---

Old Answer on debugging(no breakpoint) firebase functions using terminal:

There's a firebase documentation for Testing functions interactively using shell. You can also test https callable functions. Though steps for attaching a debugger is not mentioned there.

1. Open the Service Accounts pane of the Google Cloud Console.

2. Make sure that App Engine default service account is selected, and use the options menu at right to select Create key.

3. When prompted, select JSON for the key type, and click Create.

4. Set your Google default credentials to point to the downloaded key

   $ set GOOGLE_APPLICATION_CREDENTIALS=path\to\key.json

   $ firebase functions:shell

The Cloud Functions shell emulates all types of function triggers with an interactive shell for invoking the functions with test data. Options vary by function type, but the basic usage format is:

myFunctionName(data, options)

Solution 2

You can't debug Firebase functions without defining Firebase configuration variables first. Firebase CLI does it for you.

To debug you can try the same trick as you would do for Firebase functions unit test.

Add following lines to the index.js file before you call admin.initializeApp(functions.config().firebase):

admin.initializeApp = function () {}
functions.config = function() {
    return {
        firebase: {
          databaseURL: 'https://not-a-project.firebaseio.com',
          storageBucket: 'not-a-project.appspot.com',
        }
    };
}

You can debug Firebase functions now in a same way as any other google cloud function:

1. Install the Cloud Functions Emulator:

   npm install -g @google-cloud/functions-emulator
   

2. Start the Emulator:

   functions start
   

3. Deploy your function:

   functions deploy helloWorldFunction --trigger-http
   

   You'll get output like this:

   Waiting for operation to finish...done.
   Deploying function........done.
   Function helloWorldFunction deployed.
   
   Property | Value
   ---------|------------------------------------------------------------------------
   Name     | helloWorldFunction
   Trigger  | HTTP
   Resource | http://localhost:8010/helloWorldProject/us-central1/helloWorldFunction
   

4. To debug using the standard Node.js Debugger type:

   functions debug helloWorldFunction
   

   You'll get:

   Debugger for helloWorldFunction listening on port 5858.
   

5. Now add following lines to your launch.json VS Code

   {
       "version": "0.2.0",
       "configurations": [
           {
               "name": "Node.JS (local)",
               "type": "node",
               "request": "attach",
               "port": 5858
           }
       ]
   }
   

6. Start debugging in your VS Code and trigger your function by calling URL you've got on step #3.

   You can also trigger the function by typing functions call helloWorldFunction in the terminal.

For more details refer to the instructions here Cloud Functions Local Emulator.

Solution 3

• npm install -g @google-cloud/functions-emulator

• /functions/index.js

const admin = require('firebase-admin');

if (!admin.apps.length)
    admin.initializeApp({
    apiKey: "... your api key",
    authDomain: "... your auth domain",
    databaseURL: "... your database url",
    projectId: "... your project id",
    storageBucket: "... your storage bucket",
    messagingSenderId: "... your messaging sender id"
});

• /.vscode/launch.json

{
    // 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": "Attach Firebase",
            "port": 9229,
            "preLaunchTask": "Google Cloud Emulator"
        }
    ]
}

• /.vscode/tasks.json

{
// See https://go.microsoft.com/fwlink/?LinkId=733558
// for the documentation about the tasks.json format
"version": "2.0.0",
"tasks": [
    {
        "label": "Start",
        "type": "shell",
        "command": "functions",
        "isBackground": true,
        "args": [
            "start"
        ],
        "group": "build"
    },
    {
        "label": "Deploy",
        "type": "shell",
        "command": "functions",
        "isBackground": true,
        "options": {
            "cwd": "${workspaceFolder}/functions/"
        },
        "args": [
            "deploy",
            "--trigger-http",
            "--timeout",
            "600s",
            "api"
        ],
        "dependsOn": [
            "Start"
        ],
        "group": "build"
    },
    {
        "label": "Inspect",
        "type": "shell",
        "command": "functions",
        "isBackground": true,
        "options": {
            "cwd": "${workspaceFolder}/functions/"
        },
        "args": [
            "inspect",
            "api"
        ],
        "dependsOn": [
            "Deploy"
        ],
        "group": "build"
    },
    {
        "label": "Google Cloud Emulator",
        "dependsOn": [
            "Inspect",
        ],
        "group": "build"
    },
]

}

• start debugging "Attach Firebase"

Solution 4

Found it.

1. Add to launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "attach",
            "name": "Attach Firebase",
            "port": 9229
        }
    ]
}

2. Run:

$ firebase emulators:start --inspect-functions

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