Adapt mutating webhook to create KeptnAppCreationRequest resources

[odubajDT]

Part of #514

Pre-requisites:

• Bootstrap KeptnAppCreationRequest #612
• Implement logic for KeptnAppCreationRequest controller #613
• Adapt behaviour of KeptnAppCreationRequest controller during corner cases processing #728

Goal

Adapt webhook to generate KeptnAppCreationRequest resources to support of automatic discovery of the application, where a multi-service/single-service application will not require a user-defined KeptnApp resource.

Technical Details

Changes of mutating webhook

According to the research and a PoC we came to a conclusion that the KeptnAppCreationRequest resource should be created by mutating webhook. In the same time creation of the KeptnApp resource (in the current state only for single-service applications) should not be part of mutating webhook and will be part of the KeptnAppCreationRequest controller. We won't need two different implementations paths to distinguish anymore between a single-service of multi-service applications, although there will be a small difference.

Workflow:

Webhook receives a Pod and checks the annotations:

• if the Pod has application annotation, it is part of multi-service application (check like this)
• if it does not have them, we are dealing with a single-service application

In the second step webhook will try to retrieve KeptnAppCreationRequest resource for the application -> the name of the KeptnAppCreationRequest is the same as the name of the application (and the name of the future KeptnApp)

• if it finds it, it does nothing
• if it does not find it, webhook will create KeptnAppCreationRequest resource. Its name will be the same as the name off the application. Additionaly, the KeptnAppCreationRequest will have the following labels:
  • keptn.sh/app-type: (single-service|multi-service) -> this is important for the KeptnAppCreationRequest controller to know whether he should wait for the rest of workloads to be applied to the cluster, or can directly move on to creation of KeptnApp

Acceptance Criteria

• Mutating webhook does not create KeptnApp resources
• Mutating webhook creates KeptnAppCreationRequest resources

DoD

• Changed webhook implementation according to the description
• Unit tests
• Integration tests

Note

PoC of implementation available here: #559