@startuml
  title Staging Reverse Proxy

  participant User
  box "Firewall" #Orange
    participant fw
        note over fw: NAT between vlan \n1300 (public) addresses \nto vlan 443 (staging)
  end box
  box "1 global reverse proxy" #LightGreen
    participant FrontendHitch
    participant Varnish
  end box
  box "1 node per service (webapp, deposit)" #LightBlue
    participant Apache
    participant Gunicorn
  end box

  activate fw

  User -> FrontendHitch: https queries
  activate FrontendHitch

  FrontendHitch -> Varnish: forwards query
  note left: ssl termination

  activate Varnish

  alt #transparent cache hit
    Varnish -> FrontendHitch: returns result
    FrontendHitch --> User: returns result
  else cache missed
    Varnish -> Apache: forwards query
    activate Apache

    Apache -> Gunicorn: forwards query
    activate Gunicorn

    Gunicorn --> Apache: returns result
    deactivate Gunicorn

    Apache --> Varnish: caches and returns result
    deactivate Apache

    Varnish -> FrontendHitch: returns result
    FrontendHitch --> User: returns result

    deactivate Varnish
    deactivate FrontendHitch
  end

@enduml