Can't debug serverless app in Visual Studio Code

Question

I'm trying to find out how can I use Visual Studio Code debugger to debug serverless lambda function. For testing purposes I have very simple test lambda function:

module.exports.handler = async (event) => {
  debugger;
  console.log(111, event);
};

Then, in launch.json I created such a configuration:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "node",
            "request": "launch",
            "name": "Launch via NPM",
            "runtimeVersion": "8.4.0",
            "runtimeExecutable": "node",
            "program": "${workspaceFolder}/node_modules/.bin/sls",
            "cwd": "${workspaceRoot}",
            "args": [
                "invoke",
                "local",
                "--function",
                "test",
                "--data",
                "{foo:'bar'}"
            ],
            "port": 9229
        }
    ]
 }

Now, I'm puting a breakpoint inside my lambda function and pressing F5 to start debugger. I'm expecting then to go in code, put some watches and walk my code step-by-step. But nothing happens. No errors. No console outputs, no code paused on breakpoints. Nothing. All I get is message in debug console : /home/set/.nvm/versions/node/v8.4.0/bin/node node_modules/.bin/sls invoke local --function test --data {foo:'bar'}

If I go then in terminal and run that line I got exactly what is expected

set@set-home ~/www/blahblah/ens $ /home/set/.nvm/versions/node/v8.4.0/bin/node node_modules/.bin/sls invoke local --function test --data {foo:'bar'}
Serverless: INVOKING INVOKE
111 '{foo:bar}'

What am I doing wrong? How can I debug serverless application in Visual Studio Code?

Answer 1

I suspect you just need to get rid of the "port": 9229 bit.

I've never specified a port for debugging Serverless functions locally, but adding it to any of my working configurations produces the symptoms you observe.

---

Incidentally, you might be able to take some of the other stuff out, as well. For reference, my Serverless debug configurations typically look like this for invoking locally:

    {
        "type": "node",
        "request": "launch",
        "name": "Debug sls local",
        "program": "${workspaceFolder}/node_modules/serverless/bin/serverless",
        "args": [
            "invoke", "local", "--function", "processFirehose", "--path", "sample-event.json",
            "--stage",
            "nonprod",
        ]
    },