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Kube API Server

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In this section, we will talk about kube-apiserver in kubernetes

Kube-apiserver is the primary component in kubernetes.

Kube-apiserver is responsible for authenticating, validating requests, retrieving and Updating data in ETCD key-value store. In fact kube-apiserver is the only component that interacts directly to the etcd datastore. The other components such as kube-scheduler, kube-controller-manager and kubelet uses the API-Server to update in the cluster in their respective areas.

Installing kube-apiserver

If you are bootstrapping kube-apiserver using kubeadm tool, then you don’t need to know this, but if you are setting up using the hardway then kube-apiserver is available as a binary in the kubernetes release page.
- For example: You can downlaod the kube-apiserver v1.13.0 binary here kube-apiserver
```
$ wget https://storage.googleapis.com/kubernetes-release/release/v1.13.0/bin/linux/amd64/kube-apiserver
```

kube-apiserver

View kube-apiserver - Kubeadm

kubeadm deploys the kube-apiserver as a pod in kube-system namespace on the master node.
```
$ kubectl get pods -n kube-system
```

View kube-apiserver options - Kubeadm

You can see the options with in the pod definition file located at /etc/kubernetes/manifests/kube-apiserver.yaml
```
$ cat /etc/kubernetes/manifests/kube-apiserver.yaml
```

View kube-apiserver options - Manual

In a Non-kubeadm setup, you can inspect the options by viewing the kube-apiserver.service
```
$ cat /etc/systemd/system/kube-apiserver.service
```
You can also see the running process and effective options by listing the process on master node and searching for kube-apiserver.
```
$ ps -aux | grep kube-apiserver
```

K8s Reference Docs:

https://kubernetes.io/docs/reference/command-line-tools-reference/kube-apiserver/
https://kubernetes.io/docs/concepts/overview/components/
https://kubernetes.io/docs/concepts/overview/kubernetes-api/
https://kubernetes.io/docs/tasks/access-application-cluster/access-cluster/
https://kubernetes.io/docs/tasks/administer-cluster/access-cluster-api/