http_response: return values in case of timeout

[LeJav]

It would be nice if http_response could return values in case of timeout.
For instance, timeout value (or predefined value) for response_time and a predefined code (0 for instance) for http_response_code

Instead of having:

if err != nil {
return err
}

Do something like:

if err != nil {
fields = make(map[string]interface{})
fields["response_time"] = h.ResponseTimeout.Duration.Seconds()
fields["http_response_code"] = 0
acc.AddFields("http_response", fields, tags)
return nil
}

The timeouts will then clearly appear in graphs

[phemmer]

We should probably come up with a standard behavior for all plugins which measure response times of something, and end up timing out. We have a similar issues over at #2548 for dns_query and #1654 for the ping plugin.

[danielnelson]

There is now a result_type field that will be set to timeout upon timeout. The http_response_code will be unset.