feat(mixin): add mixin config option

[watson]

@mcollina here's the "context" PR as we talked about at NodeConf. I ended up calling the feature "mixin" instead, as I think that suits the use-case better. But feel free to suggest other names 😃

[mcollina]

Would you mind to validate that it is a function?

[jsumners]

Wouldn't this function need to be synchronous? That should be called out in the docs.

I'm not enamored with the name "mixin" but I don't have a better suggestion either.

[watson]

@mcollina

Fixed 👍

@jsumners:

Wouldn't this function need to be synchronous? That should be called out in the docs.

Yes, it should be synchronous. My intent was that this was obvious from the docs, as it says that the function "must return an object" and that "the properties of the returned object will be added to the logged JSON". So while I didn't use the word synchronous directly, I thought that the usage could easily be derived. But if you like me to specifically state that it should be called synchronous, I'll do that 👍

[jsumners]

I think it is better to be explicit because people do weird things.

[mcollina]

LGTM

[watson]

@jsumners I've updated the docs 👍

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.