KodeCloud CKA Finalizers & Owner References

Links: 111 KodeCloud Index

Finalizers & Owner References¶

Finalizers are identified as keys on resources that control the garbage collection process before deletion.
- They are used by controllers to determine which cleanup operations should be performed.
- They are a way to ensure that a Kubernetes resource is NOT deleted until certain conditions are met.
Dead finalizers are finalizer strings that the controller does not understand, leading to difficulties in deletion.
- Understanding finalizers and their associated actions can aid in debugging deletion issues.
Finalizers, present in an object's metadata, are a list of strings.
One use case for using finalizers is when there are dependent resources that should be deleted before deleting the main resource.
- Finalizers can also be used to clean up resources before deletion.
The deletion process involves updating the object with a deletion timestamp, signaling that the object can only be read (except for removing finalizer keys).
The state diagram illustrates the finalization process, showing that an object remains in the "finalization" state until the finalizers are removed by controllers.
Owner references establish relationships between objects, enabling the deletion of entire trees of resources.
- Common examples include pods referencing their replica sets.
- Child objects are associated with parent objects, and deleting the parent triggers the deletion of all dependent objects.
The cascade option allows the deletion of a parent without affecting its children.
- Using k delete --cascade=false on parent objects orphans the child objects and removes their owner references.