Improve request events instrumentation

[nguyhh]

What are you trying to accomplish?

This is an extension of the simple instrumentation callback what has been done previously in #870.

To create our own event logs of Stripe calls, we were missing certain informations when we subscribe to Request/RequestEnd. The missing informations that we would like to have access to are:

• Request headers and body
• Response headers and body

What approach did you choose and why?

We simply added the missing fields to the RequestEndEvent class.

Please correct me if I am wrong, but here is my understanding on where to retrieve the missing informations.

• Context seems to hold the information about the request
  • context.body would hold the request body information
• Resp seems to be the response
  • resp.body holds the response body
  • resp.to_hash seems to hold the hidden response headers
• The request headers were not exposed, so we are passing it through theexecute_request_with_rescues method

[CLAassistant]

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[anniel-stripe]

Hi @nguyhh, thanks so much for the contribution! Looks like there is a linting error, which you can fix by running bundle exec rake rubocop.

Otherwise the implementation looks reasonable to me! I'm going to have @pakrym-stripe take a look as well, since he has more experience with stripe-ruby.

[nguyhh]

Hi!
There was a lint error saying that the list of arguments was too long. So what I did is extract the arguments and wrap them under a RequestContext and a ResponseContext object. I wasn't really sure where these classes should live so I've put them under the Instrumentation class at the moment. Please let me know if there is a better suited place. 😄

[anniel-stripe]

Hi, thanks so much for making those changes! This LGTM :)