Log Prometheus current number of host and index

Merged Thong Kuah requested to merge load-balancing-prometheus into master

What does this MR do?

  1. Log current number of hosts and current index when #initialize is called
  2. Log current number of hosts and current index when #next is called
  3. Log current number of hosts and current index when #hosts= is called

Issue: https://gitlab.com/gitlab-org/gitlab-ee/issues/13630

CE port: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/32044

Does this MR meet the acceptance criteria?

Conformity

Performance and Testing

Manual QA

Recording of metrics after a GitLab request:

Screen_Recording_2019-08-22_at_11.31.47_AM

See https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/15440#note_206556427 for how this was tested locally

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

  • Label as security and @ mention @gitlab-com/gl-security/appsec
  • The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
  • Security reports checked/validated by a reviewer from the AppSec team
Edited by Ash McKenzie