Coerce string integer destinations to file descriptors

[jsumners]

It's easy to accidentally write code like the following and expect it "to work":

'use strict'

const pino = require('pino')
const transport = pino.transport({
  targets: [
    { target: 'pino/file', level: 'debug', options: { destination: '2' } },
    { target: 'pino/file', level: 'info', options: { destination: '1' } }
  ]
})

const log = pino({ level: 'debug' }, transport)

log.error('something bad')
log.info('it works')

Notice that the destination in each target is a string integer. The clear intention is that they write to stderr and stdout respectively. This pull request accounts for this.

[mcollina]

Should this be done inside pino.destination instead? why having it differently in transports vs there?

[jsumners]

Should this be done inside pino.destination instead? why having it differently in transports vs there?

No reason other than lack of understanding. I'll update when I get a chance.

[mcollina]

The docs for pino.destination should be updated too.

[jsumners]

🤦‍♂️ will do. I literally went back to bed after this.

[mojavelinux]

I don't understand why we need to coerce a string to a number. Isn't the differentiation between a file path and file descriptor the type? What if you want to write to a file that is named "1". Now you lose that ability. For logs, that's not an unreasonable scenario (though probably rare) since logs are often sequenced in a directory. Can't we make the user get the type right?

[jsumners]

The included docs show how to write to a file named '1'.

[mojavelinux]

That just seems really weird to me that we are not accepting what the user is providing. Sure, we can try to analyze the value and figure whether it is one or the other, but the type was already doing that.

[jsumners]

No, it wasn't. This is a reduction in surprise. Passing a single integer as a destination is a mistake and most likely an attempt to write to stdout or stderr. If the string is accepted as-is, it is not defined what will actually happen. If it does write to a file, then that file can be in the current working directory or somewhere else entirely. If a file is the intended destination then an actual file path should be specified.

[mojavelinux]

We can agree to disagree, but I think the current behavior is the logical one. An integer is a file descriptor (which might be stdout, stderr, or one the application is managing). A string is a file path. As a user of pino, that's how I understood it and that contract makes complete sense to me.

[mcollina]

lgtm

[mojavelinux]

After sitting on this for awhile, I now agree this is consistent with the *nix convention. I retract my earlier objection. Thanks for making this improvement.

[jsumners]

After sitting on this for awhile, I now agree this is consistent with the *nix convention. I retract my earlier objection. Thanks for making this improvement.

Thank you.

[github-actions]

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