pod管理调度约束、与健康状态检查

pod的管理

[root@k8s-master ~]# vim pod.yaml

apiVersion: v1

kind: Pod

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx

创建pod

[root@k8s-master ~]# kubectl create -f pod.yaml

查看pod信息

[root@k8s-master ~]# kubectl get all

po/nginx-pod

1/1 Running 0 1m

查看pod的详细信息

[root@k8s-master ~]# kubectl describe po/nginx-pod

删除创建的pod

[root@k8s-master ~]# kubectl delete -f pod.yaml

POD的资源管理

[root@k8s-master ~]# vim pod.yaml

apiVersion: v1

kind: Pod

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx

resources:

requests:

memory: "64Mi"

cpu: "250m"

limits:

memory: "128Mi"

cpu: "500m"

[root@k8s-master ~]# kubectl create -f pod.yaml

[root@k8s-master ~]# kubectl describe po/nginx-pod

Limits:

cpu: 500m

memory: 128Mi

pod调度约束与重启策略

[root@k8s-master ~]# vim pod.yaml

apiVersion: v1

kind: Pod

metadata:

labels:

app: nginx

spec:

nodeName: 192.168.30.22

nodeSelector:

env_role: dev

containers:

- name: nginx

image: nginx

[root@k8s-master ~]# kubectl create -f pod.yaml

我们指定的是pod在22主机上创建，自然也会分配到这个主机上

[root@k8s-master ~]# kubectl get pod -o wide

nginx-pod 1/1 Running 0 2m 172.17.11.3 192.168.30.22

查看主机名标签

[root@k8s-master ~]# kubectl describe node 192.168.30.22

Name: 192.168.30.22

Roles: <none>

Labels: beta.kubernetes.io/arch=amd64

beta.kubernetes.io/os=linux

kubernetes.io/hostname=192.168.30.22

添加标签

[root@k8s-master ~]# kubectl label nodes 192.168.30.22 env_role=dev

再次查看主机名标签已经把env_role=dev添加进去

[root@k8s-master ~]# kubectl describe node 192.168.30.22

Name: 192.168.30.22

Roles: <none>

Labels: beta.kubernetes.io/arch=amd64

beta.kubernetes.io/os=linux

env_role=dev

kubernetes.io/hostname=192.168.30.22

根据我们的约束再次创建pod已经又放在22主机上了

[root@k8s-master ~]# kubectl get pod -o wide

nginx-pod2 1/1 Running 0 1m 172.17.11.5 192.168.30.22

pod健康状态检查

提供 Probe 机制，有以下两种类型：

l livenessProbe

如果检查失败，将杀死容器，根据Pod的restartPolicy来操作。

l readinessProbe

如果检查失败，Kubernetes会把Pod从service endpoints中剔除。

Probe 支持以下三种检查方法：

l httpGet

发送HTTP请求，返回200-400范围状态码为成功。

l exec

执行Shell命令返回状态码是0为成功。

l tcpSocket

发起TCP Socket建立成功。

[root@k8s-master ~]# vim pod.yaml

apiVersion: v1

kind: Pod

metadata:

labels:

app: nginx

spec:

containers:

- name: nginx

image: nginx

ports:

- containerPort: 80

livenessProbe:

httpGet:

path: /index.html

port: 80

[root@k8s-master ~]# kubectl create -f pod.yaml

查看详细信息，可以看到这里容器访问80端口的信息

[root@k8s-master ~]# kubectl describe po/nginx-pod

Restart Count: 0

Liveness: http-get http://:80/index.html delay=0s timeout=1s period=10s #success=1 #failure=3

Environment: <none>

通过日志可以看到这里使用kube-probe来访问

[root@k8s-master ~]# kubectl logs nginx-pod -f

172.17.80.1 - - [08/Jul/2019:10:08:14 +0000] "GET /index.html HTTP/1.1" 200 612 "-" "kube-probe/1.9" "-"

172.17.80.1 - - [08/Jul/2019:10:08:24 +0000] "GET /index.html HTTP/1.1" 200 612 "-" "kube-probe/1.9" "-"

再开一个窗口，进入容器删除index.html看看日志的变化

[root@k8s-master ~]# kubectl exec -it nginx-pod bash

root@nginx-pod:/# cd /usr/share/nginx/html/

root@nginx-pod:/usr/share/nginx/html# ls

50x.html index.html

root@nginx-pod:/usr/share/nginx/html# rm index.html

root@nginx-pod:/usr/share/nginx/html# exit

这边10秒后显示404找不到页面了

2019/07/08 10:17:14 [error] 6#6: *55 open() "/usr/share/nginx/html/index.html" failed (2: No such file or directory), client: 172.17.80.1, server: localhost, request: "GET /index.html HTTP/1.1", host: "172.17.80.4:80"

172.17.80.1 - - [08/Jul/2019:10:17:14 +0000] "GET /index.html HTTP/1.1" 404 153 "-" "kube-probe/1.9" "-"

172.17.80.1 - - [08/Jul/2019:10:17:24 +0000] "GET /index.html HTTP/1.1" 404 153 "-" "kube-probe/1.9" "-"

查看pod的详细信息，已经输出404页面，但是它还会再创建一个容器并启动

[root@k8s-master ~]# kubectl describe pod nginx-pod

Warning Unhealthy 22s (x3 over 42s) kubelet, 192.168.30.23 Liveness probe failed: HTTP probe failed with statuscode: 404

Normal Created 5m (x2 over 14m) kubelet, 192.168.30.23 Created container

Normal Started 5m (x2 over 14m) kubelet, 192.168.30.23 Started container

进入容器再看，容器又有了

root@nginx-pod:~# cd /usr/share/nginx/html

root@nginx-pod:/usr/share/nginx/html# ls

50x.html index.html