Implement logic for KeptnAppCreationRequest controller

[odubajDT]

Part of #514

Pre-requisites :

• Bootstrap KeptnAppCreationRequest #612

Goal

Implement the controller logic to handle 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. Instead this resource will be generated automatically.

Technical Details

Implementation of Reconcile() function of KeptnAppCreationRequest controller

The controller will be the component creating/updating the KeptnApp resource according to the current state. It will fetch all workloads of the application and also takes care of waiting for the timeout to expire.

Explanationary notes:
How to know if KeptnApp is user defined:

• if the KeptnApp has a .metadata.ownerReference pointing to KeptnAppCreationRequest, it is not a user defined KeptnApp
• if it does not have this reference, it's user defined

How to know if KeptnApp is single-service or multi-service:

• if the KeptnAppCreationRequest annotation keptn.sh/app-type has value single-service -> it's single-service app and the timeout is set to 0
• if the KeptnAppCreationRequest annotation keptn.sh/app-type has value mutli-service -> it's multi-service app and the timeout is set to 30 (in the future this value will be configured from Keptn Config CRD, for now we will use a hard-coded value)

Workflow:
The controller tries to fetch the KeptnApp

• if he finds it and it is user-defined (no auto-application discovery needed), it will remove the KeptnAppCreationRequest and do not reconcile itself again
• if KeptnApp exists && is not user defined -> the controller checks the timeout -> if it's not expired yet -> reconcile
• if KeptnApp does not exist -> the controller checks the timeout -> if it's not expired yet -> reconcile

If the timeout expired (the length of the timeout is based on the information if the app is single-service or multi-service), controller fetches all the KeptnWorkloads of the appropriate application and updates/creates the KeptnApp with the correct version (depending on if it already exists or not). The Version of the KeptnApp will be computed as a hash of workload versions, which are part of the application.

• creation of KeptnApp -> controller creates new KeptnApp with all workloads of the application but without any pre- or post- deployment tasks/evaluations. Please do not forget to start a context of the App (example here) and a trace context (example here) where the traceContextCarrier needs to be stored in KeptnApp annotations
• update of KeptnApp -> controller updates the existing non user-defined KeptnApp with all the workloads of the application which are currently in the cluster

After the KeptnApp is created/updated, the KeptnAppCreationRequest should be deleted and the reconciliation loop ends -> this behaviour is needed due to possible future updates of the KeptnApp (adding/deleting workloads).

Acceptance Criteria

• KeptnAppCreationRequest controller reconciles the resources and creates/updates the appropriate KeptnApp

DoD

• Implemented controller logic according to the description
• Unit tests
• Integration tests

Note

PoC of implementation available here: #559

[bacherfl]

During implementation it turned out that we need to solve #1185 before this can be fully implemented