Inspect mode conflicts with separate processes mode

[ukrbublik]

This will not work:
node --inspect ./node_modules/serverless/bin/serverless offline --useSeparateProcesses start
Child processes will exit with code 12.
It's because they will try to share same arguments with parent sls process.

This is dirty workaround:

      const ipcProcess = fork(helperPath, [funOptions.handlerPath], {
        env: _.omitBy(process.env, _.isUndefined),
        stdio: [0, 1, 2, 'ipc'],
        execArgv: process.execArgv.filter(a => a != '--inspect')
      });

at functionHelper.js

[dherault]

noted, thanks.

[andrewc89]

I am running into this issue as well. When I run:

node --inspect ./node_modules/.bin/sls offline start --useSeparateProcesses --noAuth --stage dev --port 5000

without the changes to functionHelper.js, I get the following output:

Serverless: The first request might take a few extra seconds
Starting inspector on 127.0.0.1:9229 failed: address already in use
Serverless: Failure: Handler process exited with code 12
Serverless: Replying 200

If I remove the --useSeparateProcesses argument, everything works, including debugging. Initially I only see the node_modules in the debugger, but after hitting an endpoint, my code files are shown (which is documented in the README).

However, we are using Inversify and need to use the --useSeparateProcesses command. So after I make the changes to functionHelper.js, everything works as expected except that I don't ever get my code files loaded into the debugger.

@ukrbublik did you find a way to get your code to show up in the debugger?

I also think that when the process exits with code 12, shouldn't it reply with a 500? The 200 reply is confusing.

[ukrbublik]

@gwely

@ukrbublik did you find a way to get your code to show up in the debugger?

No.
Separate processes should use another ports for inspector (not 9229, but 9230, 9231..), it's a problem

[rdsedmundo]

I'm running in the same problem.

And I came up in the exact same conclusion:

It's because they will try to share same arguments with parent sls process.

@dherault why did you close this issue? Is this already work in progress?

[dherault]

Because of the workaround given. But let's re-open it.

[rdsedmundo]

I think his workaround was mentioning editing the plugin at this LOC: https://github.com/dherault/serverless-offline/blob/master/src/functionHelper.js#L116

[Can-Sahin]

Same issue here!

I'm using NestJS with typeorm and there is singleton issue with connections of typeorm. So i use the flag --useSeparateProcesses and it works. But this time debug launch fails with address already in use error. Same with @gwely

I have to use this flag for local development otherwise its a nightmare but now debug won't work.

What to do ? 😕

UPDATE: I don't know which update made it possible but you can name the connections with TypeOrmModule.forRootAsync({}) something random everytime and my problem disappears for running locally

[dnalborczyk]

for the purpose of debugging one should run serverless-offline in-process (not as a separate process). it might be also possible to debug child processes with ndb. I have not tried that myself yet.

that being said, in v6 we introduced running the handlers in worker threads (--useWorkerThreads option if your node.js version allows this, v11.7+ is required) and this is also recommended, and will likely be the default in future versions of this plugin.

unfortunately debugging worker threads with chrome dev tools is not yet possible as well (nodejs/node#26609), but should also be supported with ndb (GoogleChromeLabs/ndb#277)