Create garbage collection docs

content/en/docs/concepts/overview/working-with-objects/finalizers.md

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+---
+title: Finalizers
+content_type: concept
+weight: 60
+---
+
+<!-- overview -->
+
+{{<glossary_definition term_id="finalizer" length="long">}}
+
+You can use finalizers to control {{<glossary_tooltip text="garbage collection" term_id="garbage-collection">}}
+of resources by alerting {{<glossary_tooltip text="controllers" term_id="controller">}} to perform specific cleanup tasks before
+deleting the target resource. 
+
+Finalizers don't usually specify the code to execute. Instead, they are
+typically lists of keys on a specific resource similar to annotations.
+Kubernetes specifies some finalizers automatically, but you can also specify
+your own.
+
+## How finalizers work
+
+When you create a resource using a manifest file, you can specify finalizers in
+the `metadata.finalizers` field. When you attempt to delete the resource, the
+controller that manages it notices the values in the `finalizers` field and does
+the following: 
+
+  * Modifies the object to add a `metadata.deletionTimestamp` field with the
+    time you started the deletion.
+  * Marks the object as read-only until its `metadata.finalizers` field is empty.
+
+The controller then attempts to satisfy the requirements of the finalizers
+specified for that resource. Each time a finalizer condition is satisfied, the
+controller removes that key from the resource's `finalizers` field. When the
+field is empty, garbage collection continues. You can also use finalizers to
+prevent deletion of unmanaged resources.
+
+A common example of a finalizer is `kubernetes.io/pv-protection`, which prevents
+accidental deletion of `PersistentVolume` objects. When a `PersistentVolume`
+object is in use by a Pod, Kubernetes adds the `pv-protection` finalizer. If you
+try to delete the `PersistentVolume`, it enters a `Terminating` status, but the
+controller can't delete it because the finalizer exists. When the Pod stops
+using the `PersistentVolume`, Kubernetes clears the `pv-protection` finalizer,
+and the controller deletes the volume.
+
+## Owner references, labels, and finalizers {#owners-labels-finalizers}
+
+Like {{<glossary_tooltip text="labels" term_id="label">}}, [owner references](/concepts/overview/working-with-objects/owners-dependents/)
+describe the relationships between objects in Kubernetes, but are used for a
+different purpose. When a
+{{<glossary_tooltip text="controllers" term_id="controller">}} manages objects
+like Pods, it uses labels to track changes to groups of related objects. For
+example, when a {{<glossary_tooltip text="Job" term_id="job">}} creates one or
+more Pods, the Job controller applies labels to those pods and tracks changes to
+any Pods in the cluster with the same label.
+
+The Job controller also adds *owner references* to those Pods, pointing at the
+Job that created the Pods. If you delete the Job while these Pods are running,
+Kubernetes uses the owner references (not labels) to determine which Pods in the
+cluster need cleanup.
+
+Kubernetes also processes finalizers when it identifies owner references on a
+resource targeted for deletion. 
+
+In some situations, finalizers can block the deletion of dependent objects,
+which can cause the targeted owner object to remain in a read-only state for
+longer than expected without being fully deleted. In these situations, you
+should check finalizers and owner references on the target owner and dependent
+objects to troubleshoot the cause. 
+
+{{<note>}}
+In cases where objects are stuck in a deleting state, try to avoid manually
+removing finalizers to allow deletion to continue. Finalizers are usually added
+to resources for a reason, so forcefully removing them can lead to issues in
+your cluster. 
+{{</note>}}
+
+## {{% heading "whatsnext" %}}
+
+* Read [Using Finalizers to Control Deletion](/blog/2021/05/14/using-finalizers-to-control-deletion/)
+  on the Kubernetes blog.