# What's the relationship of kubernetes API server and kube-apiserver?

**URL:** <https://discuss.kubernetes.io/t/whats-the-relationship-of-kubernetes-api-server-and-kube-apiserver/19912>\
**Category:** General Discussions\
**Tags:** docs\
**Created:** [May 6, 2022, 4:08am UTC](https://discuss.kubernetes.io/t/whats-the-relationship-of-kubernetes-api-server-and-kube-apiserver/19912 "2022-05-06T04:08:02Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![markdocker07](https://avatars.discourse-cdn.com/v4/letter/m/a88e4f/32.png) [@markdocker07](https://discuss.kubernetes.io/u/markdocker07)\
**Post date:** [May 6, 2022, 4:08am UTC](https://discuss.kubernetes.io/t/whats-the-relationship-of-kubernetes-api-server-and-kube-apiserver/19912/1 "2022-05-06T04:08:02Z")

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When I read doc of [kube-apiserver](https://kubernetes.io/docs/concepts/overview/components/#kube-apiserver):

> The API server is a component of the Kubernetes [control plane](https://kubernetes.io/docs/reference/glossary/?all=true#term-control-plane) that exposes the Kubernetes API. The API server is the front end for the Kubernetes control plane.

> The main implementation of a Kubernetes API server is [kube-apiserver](https://kubernetes.io/docs/reference/generated/kube-apiserver/). kube-apiserver is designed to scale horizontally—that is, it scales by deploying more instances. You can run several instances of kube-apiserver and balance traffic between those instances

So the API server is not equals to kube-apiserver.  
what’s the relathionship of them? is it parallel to `OSI model` and `TCP/IP` protocol? the standard and implementation?

* * *

question2:  
by the way , the `api` in the diagram, is it mean the kubernetes API server or kube-apiserver?

 ![image](https://us1.discourse-cdn.com/flex016/uploads/kubernetes/original/2X/9/96b33df4b8da797315bf0950b482f155239b3d11.png)

question3: there are several`api` instances, is it mean it is `scale horizontally`?

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**Author:** ![thockin](https://sea2.discourse-cdn.com/flex016/user_avatar/discuss.kubernetes.io/thockin/32/2457_2.png) [@thockin](https://discuss.kubernetes.io/u/thockin)\
**Post date:** [May 6, 2022, 3:39pm UTC](https://discuss.kubernetes.io/t/whats-the-relationship-of-kubernetes-api-server-and-kube-apiserver/19912/2 "2022-05-06T15:39:08Z")

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> [@markdocker07](#):
>
> a Kubernetes API server

This means the abstract idea of a server which has the right REST semantics (consistent object model, watch, etc). Usually it includes the Kubernetes API types and schema, but there is a concept of a generic API server, which has the semantics but just a barebones schema, which can be used for other things (e.g. running your own system with your own types and schema).

> [@markdocker07](#):
>
> kube-apiserver

This is a specific program which implements the Kubernetes API semantics and schema.

> [@markdocker07](#):
>
> question3: there are several `api` instances, is it mean it is `scale horizontally` ?

From the doc you quoted: “kube-apiserver is designed to scale horizontally—that is, it scales by deploying more instances.”