Kubernetes 정상 작동 확인

 

● Ready 상태라고 해서 끝이 아닌, 더 확인해 봐야 한다

[vagrant@ms ~]$ kubectl get nodes
NAME              STATUS   ROLES           AGE   VERSION
ms.example.com    Ready    control-plane   41m   v1.29.2
wk1.example.com   Ready    <none>          40m   v1.29.2
wk2.example.com   Ready    <none>          40m   v1.29.2

 

 

● pods 확인을 해봐야 한다

>> kube-system 안에 있는 pods 들이 모두 Running 이 되어야 정상 작동한다

[vagrant@ms ~]$ kubectl get pods -n kube-system
NAME                                     READY   STATUS    RESTARTS   AGE
coredns-76f75df574-dnn6l                 1/1     Running   0          41m
coredns-76f75df574-xx9lp                 1/1     Running   0          41m
etcd-ms.example.com                      1/1     Running   0          41m
kube-apiserver-ms.example.com            1/1     Running   0          41m
kube-controller-manager-ms.example.com   1/1     Running   0          41m
kube-proxy-2g2fg                         1/1     Running   0          41m
kube-proxy-f86lt                         1/1     Running   0          41m
kube-proxy-ghfmd                         1/1     Running   0          41m
kube-scheduler-ms.example.com            1/1     Running   0          41m

 

 

● namespace 는 kubectl 을 경유해준다?

[vagrant@ms ~]$ kubectl get ns
NAME              STATUS   AGE
default           Active   45m
kube-flannel      Active   45m
kube-node-lease   Active   45m
kube-public       Active   45m
kube-system       Active   45m

 

● 사용하지 않고 있다

>> 하지만 kube-system 은 기본적으로 사용하며, 그대로 쓴다

[vagrant@ms ~]$ kubectl get pods
No resources found in default namespace.
[vagrant@ms ~]$ kubectl get pods -n kube-public
No resources found in kube-public namespace.

[vagrant@ms ~]$ kubectl get pods -n kube-system
NAME                                     READY   STATUS    RESTARTS   AGE
coredns-76f75df574-dnn6l                 1/1     Running   0          46m
coredns-76f75df574-xx9lp                 1/1     Running   0          46m
etcd-ms.example.com                      1/1     Running   0          46m
kube-apiserver-ms.example.com            1/1     Running   0          46m
kube-controller-manager-ms.example.com   1/1     Running   0          46m
kube-proxy-2g2fg                         1/1     Running   0          46m
kube-proxy-f86lt                         1/1     Running   0          46m
kube-proxy-ghfmd                         1/1     Running   0          46m
kube-scheduler-ms.example.com            1/1     Running   0          46m

 

 

● kube-flannel 정상작동 / kube-system 정상작동 >> 정상

# CNI ( container network interface )

[vagrant@ms ~]$ kubectl get pods -n kube-flannel
NAME                    READY   STATUS    RESTARTS   AGE
kube-flannel-ds-84jkj   1/1     Running   0          46m
kube-flannel-ds-p4lpr   1/1     Running   0          46m
kube-flannel-ds-qp7d5   1/1     Running   0          46m

 

 

 

▶ 동작 확인 작업

>> 다운로드 중

[vagrant@ms ~]$ kubectl run apache --image httpd:2.4
pod/apache created

[vagrant@ms ~]$ kubectl get pods
NAME     READY   STATUS              RESTARTS   AGE
apache   0/1     ContainerCreating   0          7s

[vagrant@ms ~]$ kubectl get pods
NAME     READY   STATUS    RESTARTS   AGE
apache   1/1     Running   0          36s

 

 

▷ 모든 pods 는 master 에서 작동 안하고 모두 worker 에서 작동한다

[vagrant@ms ~]$ kubectl get pods -o wide
NAME     READY   STATUS    RESTARTS   AGE   IP           NODE              NOMINATED NODE   READINESS GATES
apache   1/1     Running   0          55s   10.244.2.2   wk2.example.com   <none>           <none>

 

 

◎ 하나 더 생성시 부하 분산하여 자동으로 각 worker 에 균등하게 실행된다

>> pod 를 랜덤하게 배치하는게 아니라 적절하게 배치한다

# pod 는 컨테이너를 담고있는 그릇이라고 생각

[vagrant@ms ~]$ kubectl run apache2 --image httpd:2.4
pod/apache2 created

[vagrant@ms ~]$ kubectl get pods -o wide
NAME      READY   STATUS    RESTARTS   AGE    IP           NODE              NOMINATED NODE   READINESS GATES
apache    1/1     Running   0          100s   10.244.2.2   wk2.example.com   <none>           <none>
apache2   1/1     Running   0          15s    10.244.1.2   wk1.example.com   <none>           <none>

 

 

○ 직접 접속하여 문제가 없는지 확인

[vagrant@ms ~]$ curl 10.244.2.2
<html><body><h1>It works!</h1></body></html>
[vagrant@ms ~]$ curl 10.244.1.2
<html><body><h1>It works!</h1></body></html>