When functions:delete command fails it prints to stdout instead of stderr

[misha-reyzlin-hier]

[REQUIRED] Environment info

firebase-tools: 9.6.1

Platform: Ubuntu

[REQUIRED] Test case

In node repl, attempt deleting a function group that doesn’t exist, using require('child_process').exec:

> require('child_process').exec('firebase functions:delete nonExistingFunctionGroupFooBarBaz -f', function(err, stdout, stderr) { console.log(arguments) })
[Arguments] {
  '0': Error: Command failed: firebase functions:delete asdasds -f
  
      at ChildProcess.exithandler (child_process.js:308:12)
      at ChildProcess.emit (events.js:315:20)
      at ChildProcess.EventEmitter.emit (domain.js:529:15)
      at maybeClose (internal/child_process.js:1048:16)
      at Socket.<anonymous> (internal/child_process.js:439:11)
      at Socket.emit (events.js:315:20)
      at Socket.EventEmitter.emit (domain.js:529:15)
      at Pipe.<anonymous> (net.js:673:12)
      at Pipe.callbackTrampoline (internal/async_hooks.js:131:14) {
    killed: false,
    code: 1,
    signal: null,
    cmd: 'firebase functions:delete asdasds -f'
  },
  '1': '\n' +
    '\x1B[1m\x1B[31mError:\x1B[39m\x1B[22m The specified filters do not match any existing functions in project \x1B[1mhierfoods-develop\x1B[22m.\n',
  '2': ''
}

[REQUIRED] Steps to reproduce

• Install firebase-tools globally
• Change into directory that has firebase project initialised in it
• Enter node repl
• type require('child_process').exec('firebase functions:delete nonExistingFunctionGroupFooBarBaz -f', function(err, stdout, stderr) { console.log(arguments) })
• only second argument, stdout will be populated

[REQUIRED] Expected behavior

• stderr should be populated for errors

[REQUIRED] Actual behavior

• stdout is populated with error message

[bkendall]

Question for Firebasers (maybe @samtstern @abeisgoat know): have we ever separated output between stdout and stderr? My first reaction to this is that we haven't, and that making a change to that may be breaking.

@misha-reyzlin-hier: would either using the CLI as a module or providing the --json flag help out in this case? Using it as a module would allow you to catch the error in this case, I believe. The --json flag would provide parsable output on stdout (regardless of the exit code).

[samtstern]

@bkendall I believe the --json flag is meant to address the difference in use cases between "machine readable" and "human readable". Without that flag the CLI output is not part of our API and you can change it at will, parsing it is not something we explicitly guarantee.

[misha-reyzlin-hier]

Thank for your replies!

For scripting/automation, does it make sense to add a paragraph to README that mentions --json flag as the way to get appropriate command line friendly API with firebase-tools? Also that Without that flag the CLI output is not part of our API?

[bkendall]

@samtstern that's a very good description of the difference and I agree with it.

Adding some information to the README is always welcome! @misha-reyzlin-hier - if you wanted to start a PR with what would be useful to you, we could iterate on that with you 🙂 Otherwise, I'll leave this open for this particular follow-up