Node debug attach processId property not accepting custom commands

[JohnsonMG]

I am using PM2 to run many node processes and want to setup a debug configuration to attach to running processes that were not started in debug mode. As recommended in this feature request I created my own extension to handle this with a custom command that allows me to select a pid from a dropdown.

No matter how simple I make the command however, even just returning a string synchronously, I get the following error:

I have tested this command with other debug configurations (e.g. chrome debugger) and it works totally fine, processId seems to have some type validation which is rejecting it.

Extension package.json

    "name": "pm2support",
    "displayName": "pm2Support",
    "description": "Support for pm2 processes",
    "version": "0.0.1",
    "engines": {
        "vscode": "^1.30.0"
    },
    "categories": [
        "Other"
    ],
    "activationEvents": [
        "onCommand:pm2Support.getPids"
    ],
    "main": "./out/extension",
    "contributes": {
        "commands": [{
            "command": "pm2Support.getPids",
            "title": "Get pm2 pids"
        }],
        "debuggers": [
          {
            "type": "node",
            "variables": {
              "PickPm2Process": "pm2Support.getPids"
            }
          },
          {
            "type": "chrome",
            "variables": {
              "PickPm2Process": "pm2Support.getPids"
            }
          }
        ]
    },
    "scripts": {
        "vscode:prepublish": "yarn run compile",
        "compile": "tsc -p ./",
        "watch": "tsc -watch -p ./",
        "postinstall": "node ./node_modules/vscode/bin/install",
        "test": "yarn run compile && node ./node_modules/vscode/bin/test"
    },
    "devDependencies": {
        "typescript": "^3.1.4",
        "vscode": "^1.1.25",
        "tslint": "^5.8.0",
        "@types/node": "^8.10.25",
        "@types/mocha": "^2.2.42"
    }
}

extension.ts:

'use strict';
// The module 'vscode' contains the VS Code extensibility API
// Import the module and reference it with the alias vscode in your code below
import * as vscode from 'vscode';
import * as fs from 'fs';

// this method is called when your extension is activated
// your extension is activated the very first time the command is executed
export function activate(context: vscode.ExtensionContext) {
    // The command has been defined in the package.json file
    // Now provide the implementation of the command with  registerCommand
    // The commandId parameter must match the command field in package.json
    context.subscriptions.push(vscode.commands.registerCommand('pm2Support.getPids', async ():Promise<string> => {
        // The code you place here will be executed every time your command is executed

        let pidOptions: vscode.QuickPickItem[] = [];
        var pidFiles = fs.readdirSync('/Users/gavinjohnson/.pm2/pids');

        // Pull pids from files
        pidFiles.forEach(path => {
          var contents = fs.readFileSync('/Users/gavinjohnson/.pm2/pids/' + path);
          pidOptions.push({
            label: path,
            detail: contents.toString(),
          });
        });
        
         let pickPromise = vscode.window.showQuickPick(pidOptions);
         let pid = await pickPromise.then(pick => {
            if(pick !== undefined) {
              return String(pick.detail);
            } else {
              return "";
            }
         });
         vscode.window.showInformationMessage(pid);
         return pid;
       }));
}

// this method is called when your extension is deactivated
export function deactivate() {
}

launch.json:

{
      "type": "node",
      "request": "attach",
      "name": "Attach to Process",
      "processId": "${command:PickPm2Process}"
    },

code --version :
1.30.1
dea8705
x64

node -v:
v8.11.3

ProductName: Mac OS X
ProductVersion: 10.14.2
BuildVersion: 18C54

[weinand]

@JohnsonMG does it work if you use the command ID directly?
e.g.

{
      "type": "node",
      "request": "attach",
      "name": "Attach to Process",
      "processId": "${command:pm2Support.getPids}"
},

[JohnsonMG]

@JohnsonMG does it work if you use the command ID directly?
e.g.

{
      "type": "node",
      "request": "attach",
      "name": "Attach to Process",
      "processId": "${command:pm2Support.getPids}"
},

Using the command ID directly results in the same error message.
I am happy to supply more information, if you could let me know exactly what information is missing.

Do commands work for you in the processId field? I can't seem to use any commands (apart from PickProcess), let alone my custom one.

Like I stated in my original post, the command works for other fields. e.g. I can use it successfully with the "port" parameter. It seems like the processId field specifically has some validation which rejects commands.

[JohnsonMG]

@weinand Does this still need more information? Please advise on what you would like if so.

[JohnsonMG]

@weinand Since there has been no movement on this I decided to poke around and found this:
https://github.com/microsoft/vscode-node-debug/blob/3bb7e131ba706ecb70bd9ae68e6994256c0e4f2a/src/node/extension/processPicker.ts#L49

It looks like the attach handler has hardcoded in a check for the string '${command:PickProcess}' rather than running any passed in command.

For anyone attempting to do something similar, I got around this by having my custom extension just start a debugging session itself, rather than resolving a string.

const config: vscode.DebugConfiguration = {
            "type": "node",
            "request": "attach",
            "name": "Attach to PM2 ProcessId",
            "processId": pick.detail,
          };

          vscode.debug.startDebugging(undefined, config).then(...

Where pick.detail is the showQuickPick result

Now instead of starting a debug session, I just run my command from the palette and the debugger attaches automatically.

[weinand]

The hardcoded check for '${command:PickProcess}' will become obsolete in the January release when we release the new 'resolveDebugConfigurationWithSubstitutedVariables' hook that provides access to substituted variables. Please see #87450.

[vscodebot]

This issue has been closed automatically because it needs more information and has not had recent activity. See also our issue reporting guidelines.

Happy Coding!

[weinand]

@connor4312 I have removed the code that resolves command variables (e.g. the process picker) in resolveDebugConfiguration and now let VS Code do the resolving. This makes it possible to use any command variable for the processId attribute.

[connor4312]

Sounds good, updated js-debug similarly.