Kubernets pod exists finalizers are always in terminating state

Metadata 

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Defines the original data of the object ,namespace Is used to place objects , Objects can pass through namespace Isolation .

Any kubernetes The objects of are divided into two categories , A class of objects like nodes , A computing node belongs to the entire cluster , Such objects are nonnamespace, its namespace The value is always empty .

The other is pod,service, All belong to a tenant / User , These objects belong to namespace.

An object namespace+name It represents the unique value in the whole cluster .

 typemeta Defines what I am ,metadata Defines who I am .

Finalizer

If you only contact the community kubernetes, So right. Finalizer There may not be too many concepts ,Finalizer Itself is a resource lock .

An object , When we created it , Send the request for this object to apiserver,apiserver After authentication, it is stored in etcd, If you delete this object , It also goes through the same link , It finally came from etcd Delete , The deletion itself is a physical deletion , amount to etcd This data is erased , The object disappears .

If the controller is written to monitor this object , Then it will listen to the creation of this object , Once this object is created, it will do something , When the object is deleted, it will do other things , We can't believe that the system is always working , Suppose the controller is wrong , Or the controller is being upgraded , The controller is not working at this time , Delete the object at this time , Suppose the object disappears , So this event has disappeared , After this object is deleted , Then start my controller , The controller cannot see the event that this object was deleted before , Because this event has already occurred before the controller is started , When starting a new controller instance , There is no notification of this message , Therefore, the event of object deletion is lost .

therefore fanalizer It is essentially a resource lock , An object is added finalizer, Physical deletion will not be performed when deleting objects , It will do logical deletion , In fact, it is in the event stamp of its attribute deletetimestamp Set to delete the timestamp at that moment .

The advantage is that when the user deletes an object , If the object has finalizer, Then this object will not disappear , The controller can then capture the event , Even when the controller is under maintenance , Then you can see this event after restarting , When an object is found deletetimestamp Not empty , Indicates that the user wants to delete it , Then some logic processing can be done in the controller .

When we allocate external resources , For example, create a pod, This pod After creation , We need to configure some external networks , Or configure external dns, External load balancing , At this time, you need to add finalizer, Then I need to write a controller , The controller is configured externally dns, Configure external dns We have to add finalizer, I configured the controller to add , Plus finalizer Then the object is locked , As long as it has finalizer Will not be physically deleted , When I delete this object , The controller will see update Events , See this object deletetimestamp Not empty , So this controller To clear the external configuration , When the external configuration is cleared , So by the controler take finalizer Delete the , After removal ,k8s Find this object finalizer It's empty , Then it will automatically change from logical deletion to physical deletion , The object disappears .

therefore finalizer It's a resource lock .

 

 

 

Pod Always in Terminating state There is Finalizers

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k8s Resources metadata If it exists in finalizers , Then the resource is generally created by a program , And in it

Of the created resource metadata Inside finalizers Added its logo , This means that this resource needs to be deleted

The program that creates the resource will clean up before deleting , After cleaning it up, you need to remove the ID from the finalizers Remove , however

Then the resources will finally be completely deleted .

such as Rancher Some resources created will be written finalizers identification .

Handling suggestions ： kubectl edit Edit the resource definition manually , Delete finalizers , Then look at resources , You will find

It has been deleted