Hello,
this is a second revamp of pull request #113, implementing poor man`s alternative for URL endpoint usage tracking.

New features:

• per-url param metric

  • collects hits per first defined url param from param_collect_list, attaching its value as param label
  • creates kong_http_url_param_total or kong_http_url_param_consumer_total depending on per_consumer switch
  • optionally extracts/validates param label value according to param_value_extract regexp, (to avoid possible problems with metric cardinality)

• per-url location metric

  • collects hits per ngx.var.uri ($uri) location, attaching its value as location label
  • creates kong_http_url_location_total or kong_http_url_location_consumer_total depending on per_consumer switch
  • optionally extracts/validates location label value according to location_extract regexp

These new metrics make sense especially for people that don't want to setup/run/maintain additional log-collection/extraction system (like fluentd/splunk) or implement any other kind of instrumentation systems. With this, they can still have at least a basic insight about per-consumer usage of their services identified by URL param and/or URL location (part).

Ideally, this features should be used together with consumer authentication (as it is in our use case), to further reduce possible metrics overpopulation problems.

Thank you