support koa-graphql

[sibelius]

Is your feature request related to a problem? Please describe.
We use koa-graphql instead of express-graphql, so we'd like to support it

Describe the solution you'd like
Create something like this https://github.com/elastic/apm-agent-nodejs/blob/master/lib/instrumentation/modules/express-graphql.js for koa-graphql

Describe alternatives you've considered
how can I add this custom instrumentations to my own code without modifying this package?

Additional context

if I implement this for koa-graphql, the transaction name will be the operation name of the GraphQL query/mutation?

[trentm]

Hi. Theoretically you can implement the instrumentation yourself and call apm.addPatch(...) to have the APM agent automatically load your instrumentation file when koa-graphql is require()d. However, practically, there aren't a lot of examples and usage of this, so it might be a little painful to get going.

If you are willing, you could start a PR for this and we could try to help you get it working. I'm not familiar with koa-graphql to know if it would potentially be a very similar implementation to the express-graphql instrumentation.

[sibelius]

we added a custom label per operation name, it works well