add custom parameters to transactions

[imkira]

According to http://docs.newrelic.com/docs/features/collecting-custom-parameters
newrelic agent for node.js is the only agent not supporting custom parameters.
This is a very important feature for me so I decided to investigate why.
By looking at the following piece of code

node-newrelic/lib/transaction/trace.js

Line 134 in a6f8b61

* 2: a dictionary containing custom parameters (currently not user-modifiable)

I noticed that it is actually sending custom parameters to the server, but for some reason they are "non modifiable".
Trying to understand the "currently not user-modifiable" comment, does it mean "not modifiable, PERIOD" or "not easily modifiable but if you find a way to stuff parameters in then I will send them for you"?

I really need this feature.
Is it too troublesome, or time consuming to implement? Is it on the roadmap? Do you have plans for this?
I would be glad to contribute if you give me the some directions on what exactly would be required to make this properly.

[othiym23]

Good question! The main reason we don't support custom parameters for Node traces is that we haven't gotten around to it yet. There are two problems to be solved:

1. Deciding upon the right API surface, and
2. Dealing with the various naming conventions and strategies needed to make sure that New Relic will properly format and display custom parameters

It's probably a simple enough feature to add, but it'll require testing, documentation, and the like. Custom parameters, metrics, and instrumentation are close to the top of our list of things to add, and should be coming pretty soon. If you want to try hacking things up for yourself in the meantime, you can give it a shot, but don't be surprised if things get weird.

[imkira]

Hi @othiym23 thanks for the prompt reply!

1. Deciding upon the right API surface, and

I suppose the external facade API with which the user interacts in order to add custom parameters to transactions is the most important API surface to have in mind when it comes to design decisions. Are you also referring to the internal API design?

1. Dealing with the various naming conventions and strategies needed to make sure that New Relic will properly format and display custom parameters

Is there any official documentation on this?
I was thinking on kind of porting ruby's newrelic/rpm implementation of custom parameters into newrelic/node-newrelic.

[othiym23]

What documentation... 😒

Actually, it's not as bad as that. We're moving to a new, more consistent way of handing transaction attributes, that will be much better documented (at least internally), but for now, it's mostly lore. The a Ruby or Python agent approach is probably the one we'll follow.

And I was referring exclusively to the outward-facing API -- it should look like the other agents', but there's some special-purpose logging and error-handling for Node because of the complexity of the async transaction tracer (which is an issue for us, not you -- that was me explaining why the feature wasn't there yet).

[imkira]

Got it! I will close this for now and, if I manage to cook something in the meanwhile, I'll keep you posted.
Thanks!