CODEWITHSUNDEEP
dockerkubernetes
lvthillo
lvthillo

Reputation: 30723

Which Kubernetes component creates a new pod?

I have a problem to understand the kubernetes workflow: So as I understand the flow:

You have a master which contains etcd, api-server, controller manager and scheduler. You have nodes which contain pods (wich contain containers), kubelet and a proxy.

The proxy is working as a basic proxy to make it possible for a service to communicate with other nodes. When a pod dies, the controller manager will see this (it 'reads' the replication controller which describes how many pods there normally are).

unclear: The controller manager will inform the API-server (I'm not right about this). The API-server will tell the scheduler to search a new place for the pod. After the scheduler has found a good place, the API will inform kubelet to create a new pod.

I'm not sure about the last scenario? Can you tell me the right proces is a clear way? Which component is creating the pod and container? Is it kubelet?

Upvotes: 1

Views: 437

Answers (1)

Christian Grabowski
Christian Grabowski

Reputation: 2882

So it's the kubelet that actually creates the pods and talks to the docker daemon. If you do a docker ps -a on your nodes (as in not master) in your cluster, you'll see the containers in your pod running. So the workflow is run a kubectl command, that goes to the API server, which passes it to the controller, say that command was to spawn a pod, the controller relays that to the API server which then goes to the scheduler and tells it to spawn the pod. Then the kubelet is told to spawn said pod.

I suggest reading the Borg paper that Kubernetes is based on to better understand things in further detail. http://static.googleusercontent.com/media/research.google.com/en//pubs/archive/43438.pdf

Upvotes: 3

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