Create a playbook for debugging problems in Core services

[mshustov]

Kibana Core team owns low-level services that are used by other plugins, problems in these services are quite often caused by environment setup, not a problem in a Kibana service itself. Since we are involved in investigating such incidents, we should create a playbook for debugging problems in the local and the Cloud environments.
Topics:

• Kibana < -- > Elasticsearch connection problems
  • connect ECONNREFUSED
  • ECONNRESET: Socket was closed by the client
  • socket hang up
  • No Living connections
  • 502 Bad gateway
  • reading tcpdump
  • circuit_breaking_exception (Data too large, data for [..] would be...)
• Cloud issues
  • no Kiaban <---> Elasticsearch connection
• debugging query performance
• debug memory leaks
• errors in UI or HTTP responses are likely caused by an underlying problem in a Solution code, check logs
• license level
  • license is available
  • license level is sufficient to use a feature

[elasticmachine]

Pinging @elastic/kibana-core (Team:Core)

[mshustov]

another case to cover:

• a firewall blocks some requests from the Kibana app to the Kibana server. a HAR file shows these requests as having 0 status in blocking phase