CertLoader.UpdateCertifcate() refactor

[mlajkim]

Background

Before the pr #111, there was not enough check and cert loader panicked.
The changes however has three different uploading part.

It will be great to bring it as one as the following instead:

TODOs

• Refactor it
• Make sure to thoroughly test the flow as it might bring potential bugs

[mlajkim]

plantuml code used here:

@startuml

title Run() SIA v3.2

note right
  1. Run() runs once a day, if every step is successful
  2. If anyone of them fails, it restarts from the beginning
    (Specifically defined failures won't restart the process)

end note

start
  repeat
    if (idConfig.ProviderService != ""?) then (not empty)
        #lightblue:IdentityProvisioning();
      (not given) elseif (CERT_FILE & KEY_FILE both given?) then (given)
        #red:Attempts to read instance cert on local directory;
      else (not given)
        :Write a debug
        "Skipping to request/load x509 certificate";
      endif
    if (Successfully Prepared Instance Cert?) then (no)
        if (IS BACKUP_MODE "read" or "read+write" && idConfig.ProviderService != ""?) then (yes)
          #lightblue:Attempts to read from k8s secret;
        else (no)
          :Write a debug
          "Skipping to load backup from k8s secret";
        endif
    else (yes)
    endif
  repeat while (Successfully prepared instance cert?)  is (failed to prepare)
  if (Is K8s Backup Secret used?) then (no)
  else (yes)
    #lightblue:IdentityProvisioning() with FORCE_INIT;
    note right
      It is just an attempt.
      If it fails, it does not restart the flow,
      as the instance cert is already prepared.
    end note
  endif
  note right
    Saves instance certificate into the cert reloader
  end note
  :CertReloader.UpdateCertificate();
  :RoleCertProvisioningRequest();
  :WriteFile();
  note right
    Color #lightblue: WriteFile() Should WRITE InstanceCert
    Color #red: WriteFile() Should NOT write InstanceCert
  end note
stop
@enduml