Add google-cloud-profiler to ruby projects: `gstg` experiment
When we first enabled continuous profiling for go-applications in gitlab-com/gl-infra&200 (closed) there was no ruby library to do the same for our ruby-codebase (Sidekiq & web services).
Since then the google-cloud-profiler rubygem has been released. So we should look into adding it as well.
For go services, we've implemented this through labkit: https://gitlab.com/gitlab-org/labkit/blob/b312b8c107babacd5120aeaa860918449af38116/monitoring/profiler.go#L19. I think we could use the same kind of configuration through an env-variable to configure it. For most of our go-services (except KAS) this is how we've configured it: GITLAB_CONTINUOUS_PROFILING: stackdriver?service=gitlab-pages
. We should support the same kind of configuration for Rails.