[APM] Show http url in the Span details

[hmdhk]

Background

The information is stored in the span context and merged in elastic/apm-server#1037

Please note that this is the full url therefore it might be long.

An example of the context:

{
  "context": {
    "http": {
      "url": "http://example.com"
    }
  }
}

Design

[elasticmachine]

Pinging @elastic/apm-ui

[formgeist]

@elastic/apm-agent-devs Quick question; is this something that is applicable for all agents (not only RUM) to show the URL for spans (when available) in the Span details view?

[axw]

Yes, I think so. I've just recently added it to the Go agent: elastic/apm-agent-go#172.

[felixbarny]

The Java agent does not use that field yet, but we'll also add it.

[formgeist]

I've made a design proposal for adding it to the new Span detail flyout (which is included in DT).

cc @elastic/apm-ui

[beniwohli]

I think it should have the same prominence in the UI as the SQL query, as the URL is about as important for an external request span as the SQL query is for a DB span. Having both in one span doesn't make much sense anyway.

[formgeist]

@beniwohli OK, thanks for the feedback. I'll update the design to have the URL be more prominent.

[formgeist]

Updated design proposal - moving the URL to its own row and made the URL value bigger

[beniwohli]

@formgeist my suggestion was more to show the URL for an external request span exactly like we show the SQL statement in a DB span. You won't have both, a DB span doesn't have a context.http.url and an external request span won't have a context.db.query (or whatever we decided to call that, can't remember).

I had a quick talk with @watson, and he agrees.

[formgeist]

Alrighty, thanks for the clarification - I've updated the screen to have the HTTP URL in a similar style as the DB Statement. Do we want to call it HTTP URL as a title?

[beniwohli]

Awesome, LGTM!