Kubernetes附加组件 – Tech 学习之路

一、 DNS服务

k8s集群中DNS服务主要用于将Service资源的名称解析成对应的Cluster IP地址。

DNS服务部署完毕后，现有Pod资源不会加载DNS资源，仅新创建的Pod资源会引用DNS服务。

1. 安装DNS服务

准备镜像

docker load -i 镜像包
docker tag 镜像名称:版本仓库地址:端口/镜像名称:版本
docker push 仓库地址:端口/镜像名称:版本

[root@k8s-registry ~]# docker load -i docker_k8s_dns.tar.gz 
......
Loaded image: gcr.io/google_containers/kubedns-amd64:1.9
......
Loaded image: gcr.io/google_containers/kube-dnsmasq-amd64:1.4
......
Loaded image: gcr.io/google_containers/dnsmasq-metrics-amd64:1.0
......
Loaded image: gcr.io/google_containers/exechealthz-amd64:1.2
[root@k8s-registry ~]# docker tag gcr.io/google_containers/kubedns-amd64:1.9 10.0.0.140:5000/kubedns-amd64:1.9
[root@k8s-registry ~]# docker tag gcr.io/google_containers/kube-dnsmasq-amd64:1.4 10.0.0.140:5000/kube-dnsmasq-amd64:1.4
[root@k8s-registry ~]# docker tag gcr.io/google_containers/dnsmasq-metrics-amd64:1.0 10.0.0.140:5000/dnsmasq-metrics-amd64:1.0
[root@k8s-registry ~]# docker tag gcr.io/google_containers/exechealthz-amd64:1.2 10.0.0.140:5000/exechealthz-amd64:1.2
[root@k8s-registry ~]# docker push 10.0.0.140:5000/exechealthz-amd64:1.2
......
1.2: digest: sha256:34722333f0cd0b891b61c9e0efa31913f22157e341a3aabb79967305d4e78260 size: 1358
[root@k8s-registry ~]# docker push 10.0.0.140:5000/dnsmasq-metrics-amd64:1.0 
......
1.0: digest: sha256:4767af0aee3355cdac7abfe0d7ac1432492f088e7fcf07128d38cd2f23268638 size: 1357
[root@k8s-registry ~]# docker push 10.0.0.140:5000/kube-dnsmasq-amd64:1.4 
......
1.4: digest: sha256:f7590551a628ec30ab47f188040f51c61e53e969a19ef44846754ba376b4ce21 size: 1563
[root@k8s-registry ~]# docker push 10.0.0.140:5000/kubedns-amd64:1.9 
......
1.9: digest: sha256:df5392e5c76d8519301d1d2ee582453fd9185572bcd44dc0da466b9ab220c985 size: 945

准备配置文件

# skydns deployment资源
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
spec:
  replicas: 2
  strategy: #deploy滚动升级策略
    rollingUpdate:
      maxSurge: 10%
      maxUnavailable: 0
  selector:
    matchLabels:
      k8s-app: kube-dns
  template:
    metadata:
      labels:
        k8s-app: kube-dns
      annotations:
        scheduler.alpha.kubernetes.io/critical-pod: ''
        scheduler.alpha.kubernetes.io/tolerations: '[{"key":"CriticalAddonsOnly", "operator":"Exists"}]'
    spec:
      nodeName: 10.0.0.130 #将容器调度到指定节点
      # 仅为演示参数功能，实际中并不建议使用
      containers:
      - name: kubedns
        image: 10.0.0.140:5000/kubedns-amd64:1.9
        resources:
          limits:
            memory: 308Mi
          requests:
            cpu: 100m
            memory: 200Mi
        livenessProbe:
        # 健康检查
          httpGet:
            path: /healthz-kubedns
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        readinessProbe:
        # 可用性检查
          httpGet:
            path: /readiness
            port: 8081
            scheme: HTTP
          initialDelaySeconds: 3
          timeoutSeconds: 5
        args:
        - --domain=cluster.local
        - --dns-port=10053
        - --config-map=kube-dns
        - --kube-master-url=http://10.0.0.110:10000 #指向apiServer的地址
        - --v=0
        env:
        - name: PROMETHEUS_PORT
          value: "10055"
        ports:
        - containerPort: 10053
          name: dns-local
          protocol: UDP
        - containerPort: 10053
          name: dns-tcp-local
          protocol: TCP
        - containerPort: 10055
          name: metrics
          protocol: TCP
      - name: dnsmasq
        image: 10.0.0.140:5000/kube-dnsmasq-amd64:1.4
        livenessProbe: 
          httpGet:
            path: /healthz-dnsmasq
            port: 8080
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --cache-size=1000
        - --no-resolv
        - --server=127.0.0.1#10053
        ports:
        - containerPort: 53
          name: dns
          protocol: UDP
        - containerPort: 53
          name: dns-tcp
          protocol: TCP
        resources:
          requests:
            cpu: 150m
            memory: 10Mi
      - name: dnsmasq-metrics
        image: 10.0.0.140:5000/dnsmasq-metrics-amd64:1.0
        livenessProbe:
          httpGet:
            path: metrics
            port: 10054
            scheme: HTTP
          initialDelaySeconds: 60
          timeoutSeconds: 5
          successThreshold: 1
          failureThreshold: 5
        args:
        - --v=2
        - --logtostderr
        ports:
        - containerPort: 10054
          name: metrics
          protocol: TCP
        resources:
          requests:
            memory: 10Mi
      - name: healthz
        image: 10.0.0.140:5000/exechealthz-amd64:1.2
        resources:
          limits:
            memory: 50Mi
          requests:
            cpu: 10m
            memory: 50Mi
        args:
        - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1 >/dev/null
        - --url=/healthz-dnsmasq
        - --cmd=nslookup kubernetes.default.svc.cluster.local 127.0.0.1:10053 >/dev/null
        - --url=healthz-kubedns
        - --port=8080
        - --quiet
        ports:
        - containerPort: 8080
          protocol: TCP
      dnsPolicy: Default

[root@k8s-master ~]# mkdir k8s_yaml/dns && cd k8s_yaml/dns
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get node
NAME         STATUS    AGE
10.0.0.120   Ready     23h
10.0.0.130   Ready     23h
[root@k8s-master ~/k8s_yaml/dns]# cat skydns-deploy.yml
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 create -f skydns-deploy.yml 
deployment "kube-dns" created
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get all -o wide -n kube-system
NAME              DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/kube-dns   2         2         2            2           34s

NAME                     DESIRED   CURRENT   READY     AGE       CONTAINER(S)                              IMAGE(S)                                                                                                                                                   SELECTOR
rs/kube-dns-2134347918   2         2         2         34s       kubedns,dnsmasq,dnsmasq-metrics,healthz   10.0.0.140:5000/kubedns-amd64:1.9,10.0.0.140:5000/kube-dnsmasq-amd64:1.4,10.0.0.140:5000/dnsmasq-metrics-amd64:1.0,10.0.0.140:5000/exechealthz-amd64:1.2   k8s-app=kube-dns,pod-template-hash=2134347918

NAME                           READY     STATUS    RESTARTS   AGE       IP            NODE
po/kube-dns-2134347918-d78jc   4/4       Running   0          34s       192.168.7.3   10.0.0.130
po/kube-dns-2134347918-nvd49   4/4       Running   0          34s       192.168.7.2   10.0.0.130
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get all -o wide
NAME             CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE       SELECTOR
svc/kubernetes   10.100.0.1   <none>        443/TCP   21h       <none>

# skydns svc资源
apiVersion: v1
kind: Service
metadata:
  name: kube-dns
  namespace: kube-system
  labels:
    k8s-app: kube-dns
    kubernetes.io/cluster-service: "true"
    kubernetes.io/name: "KubeDNS"
spec:
  selector:
    k8s-app: kube-dns
  clusterIP: 10.100.1.1
  ports:
  - name: dns
    port: 53
    protocol: UDP
  - name: dns-tcp
    port: 53
    protocol: TCP

[root@k8s-master ~/k8s_yaml/dns]# cat skydns-svc.yml 
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get deploy -n kube-system --show-labels
NAME       DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE       LABELS
kube-dns   2         2         2            2           13m       k8s-app=kube-dns,kubernetes.io/cluster-service=true
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get pod -n kube-system --show-labels 
NAME                        READY     STATUS    RESTARTS   AGE       LABELS
kube-dns-2134347918-d78jc   4/4       Running   0          13m       k8s-app=kube-dns,pod-template-hash=2134347918
kube-dns-2134347918-nvd49   4/4       Running   0          13m       k8s-app=kube-dns,pod-template-hash=2134347918
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 create -f skydns-svc.yml 
service "kube-dns" created
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get svc -n kube-system -o wide
NAME       CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGE       SELECTOR
kube-dns   10.100.1.1   <none>        53/UDP,53/TCP   56s       k8s-app=kube-dns
[root@k8s-master ~/k8s_yaml/dns]# kubectl -s http://10.0.0.110:10000 get all -n kube-system
NAME              DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/kube-dns   2         2         2            2           16m

NAME           CLUSTER-IP   EXTERNAL-IP   PORT(S)         AGE
svc/kube-dns   10.100.1.1   <none>        53/UDP,53/TCP   26s

NAME                     DESIRED   CURRENT   READY     AGE
rs/kube-dns-2134347918   2         2         2         16m

NAME                           READY     STATUS    RESTARTS   AGE
po/kube-dns-2134347918-d78jc   4/4       Running   0          16m
po/kube-dns-2134347918-nvd49   4/4       Running   0          16m

2. 修改kubelet参数

所有node节点kubelet服务配置文件都需更改

#/etc/kubernetes/kubelet
KUBELET_ARGS="--cluster_dns=IP地址 --cluster_domain=cluster.local" #指定k8s集群DNS服务的Cluster IP地址

[root@k8s-node01 ~]# tail -2 /etc/kubernetes/kubelet
# Add your own!
KUBELET_ARGS="--cluster_dns=10.100.1.1 --cluster_domain=cluster.local"

[root@k8s-node02 ~]# tail -2 /etc/kubernetes/kubelet
# Add your own!
KUBELET_ARGS="--cluster_dns=10.100.1.1 --cluster_domain=cluster.local"

systemctl restart kubelet.service

[root@k8s-node01 ~]# systemctl restart kubelet.service

[root@k8s-node02 ~]# systemctl restart kubelet.service

3. 验证DNS服务

[root@k8s-master ~]# cd k8s_yaml/
[root@k8s-master ~/k8s_yaml]# mkdir tomcat+mysql
[root@k8s-master ~/k8s_yaml]# mv *.yaml ./tomcat+mysql/
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# ls
k8s_deploy_mysql.yaml  k8s_deploy_tomcat.yaml  k8s_svc_mysql.yaml  k8s_svc_tomcat.yaml
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# tail -5 k8s_deploy_tomcat.yaml
        env:
        - name: MYSQL_SERVICE_HOST
          value: 'mysql'
        - name: MYSQL_SERVICE_PORT
          value: '3306'
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 get all 
NAME             CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
svc/kubernetes   10.100.0.1   <none>        443/TCP   22h
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 create -f .
deployment "mysql" created
deployment "tomcat" created
service "mysql" created
service "tomcat" created
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# curl -sI  10.0.0.120:8080/demo/ | sed -n 1,2p
HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 get all -o wide
NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/mysql    1         1         1            1           5m
deploy/tomcat   3         3         3            3           5m

NAME             CLUSTER-IP       EXTERNAL-IP   PORT(S)         AGE       SELECTOR
svc/kubernetes   10.100.0.1       <none>        443/TCP         23h       <none>
svc/mysql        10.100.117.159   <none>        3306/TCP        5m        app=mysql
svc/tomcat       10.100.229.229   <nodes>       8080:8080/TCP   5m        app=tomcat

NAME                  DESIRED   CURRENT   READY     AGE       CONTAINER(S)   IMAGE(S)                        SELECTOR
rs/mysql-3158564321   1         1         1         5m        mysql          10.0.0.140:5000/mysql:5.7       app=mysql,pod-template-hash=3158564321
rs/tomcat-627834460   3         3         3         5m        mysql          10.0.0.140:5000/tomcat-app:v2   app=tomcat,pod-template-hash=627834460

NAME                        READY     STATUS    RESTARTS   AGE       IP             NODE
po/mysql-3158564321-r31zd   1/1       Running   0          5m        192.168.16.2   10.0.0.120
po/tomcat-627834460-0slgc   1/1       Running   0          5m        192.168.16.3   10.0.0.120
po/tomcat-627834460-6bdcg   1/1       Running   0          5m        192.168.7.4    10.0.0.130
po/tomcat-627834460-mxb3r   1/1       Running   0          5m        192.168.16.4   10.0.0.120

[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 exec -it tomcat-627834460-0slgc /bin/bash
root@tomcat-627834460-0slgc:/usr/local/tomcat# cat /etc/resolv.conf 
search default.svc.cluster.local svc.cluster.local cluster.local
nameserver 10.100.1.1
nameserver 10.0.0.254
options ndots:5
root@tomcat-627834460-0slgc:/usr/local/tomcat# ping baidu.com -c1
PING baidu.com (220.181.38.148): 56 data bytes
64 bytes from 220.181.38.148: icmp_seq=0 ttl=127 time=8.948 ms
--- baidu.com ping statistics ---
1 packets transmitted, 1 packets received, 0% packet loss
round-trip min/avg/max/stddev = 8.948/8.948/8.948/0.000 ms
root@tomcat-627834460-0slgc:/usr/local/tomcat# ping mysql -c1 -w1
PING mysql.default.svc.cluster.local (10.100.117.159): 56 data bytes
--- mysql.default.svc.cluster.local ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss

二、 namespace

k8s集群的namespace资源，用于实现k8s集群的资源隔离。

kubectl get namespace #查看当前k8s集群namespace信息
kubectl get all -n namespace名称 #查看指定namespace空间的所有资源
kubectl get all --namespace namespace名称 #查看指定namespace空间的所有资源
kubectl create namespace namespace名称 #创建namespace资源

[root@k8s-master ~]# kubectl -s http://10.0.0.110:10000 get namespace 
NAME          STATUS    AGE
default       Active    361d
kube-system   Active    361d

# 资源指定namespace属性
apiVersion: 版本
kind: 资源类型
metadata:

namespace: 名称

name: 名称

spec:

......

# Tomcat + MySQL示例
[root@k8s-master ~]# cd k8s_yaml/tomcat+mysql/
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# sed -i '3a \ \ namespace: tomcat' *
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# head -5 *
==> k8s_deploy_mysql.yaml <==
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  namespace: tomcat
  name: mysql

==> k8s_deploy_tomcat.yaml <==
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  namespace: tomcat
  name: tomcat

==> k8s_svc_mysql.yaml <==
apiVersion: v1
kind: Service
metadata:
  namespace: tomcat
  name: mysql

==> k8s_svc_tomcat.yaml <==
apiVersion: v1
kind: Service
metadata:
  namespace: tomcat
  name: tomcat

[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 create namespace tomcat
namespace "tomcat" created
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 get namespace 
NAME          STATUS    AGE
default       Active    361d
kube-system   Active    361d
tomcat        Active    10s
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 create -f .
deployment "mysql" created
deployment "tomcat" created
service "mysql" created
service "tomcat" created
[root@k8s-master ~/k8s_yaml/tomcat+mysql]# kubectl -s http://10.0.0.110:10000 get all -n tomcat
NAME            DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/mysql    1         1         1            0           13s
deploy/tomcat   3         3         3            0           13s

NAME         CLUSTER-IP      EXTERNAL-IP   PORT(S)         AGE
svc/mysql    10.100.82.28    <none>        3306/TCP        13s
svc/tomcat   10.100.30.178   <nodes>       8080:8080/TCP   13s

NAME                  DESIRED   CURRENT   READY     AGE
rs/mysql-3158564321   1         1         1         13s
rs/tomcat-627834460   3         3         3         13s

NAME                        READY     STATUS    RESTARTS   AGE
po/mysql-3158564321-xxs1g   1/1       Running   0          13s
po/tomcat-627834460-ft2jh   1/1       Running   0          13s
po/tomcat-627834460-j64q0   1/1       Running   0          13s
po/tomcat-627834460-vkssq   1/1       Running   0          13s

三、健康检查

1. 探针的种类

livenessProbe - 健康状态检查

健康状态检查：周期性检查服务是否存活，若检查结果失败，将重启容器。
readinessProbe - 可用性检查

可用性检查：周期性检查服务是否可用，若服务不可用，则把该业务节点从service的endpoints中移除。

apiVersion: 版本
kind: 资源类型
metadata:

name: 名称

spec:

replicas: n

template:

metadata:

labels:

app: 名称

spec:

containers:

- name: 名称

image: 镜像仓库:端口/镜像名称:版本

livenessProbe:

探针检测方法:

......

initialDelaySeconds: n #初始化健康检查间隔时间(单位: 秒)

periodSeconds: n #健康检查执行周期(单位: 秒)

timeoutSeconds: n #健康检查超时时间(单位: 秒)

successThreshold: n #健康检查成功阈值(单位: 次)

failureThreshold: n #健康检查失败阈值(单位: 次)

readinessProbe:

探针检测方法:

......

initialDelaySeconds: n #初始化可用性检查间隔时间(单位: 秒)

periodSeconds: n #可用性检查执行周期(单位: 秒)

timeoutSeconds: n #可用性检查超时时间(单位: 秒)

successThreshold: n #可用性检查成功阈值(单位: 次)

failureThreshold: n #可用性检查失败阈值(单位: 次)

2. 探针的检测方法

exec: 执行一段命令；返回值0，非0。
httpGet: 检测HTTP请求返回的健康状态代码(2xx，3xx为正常状态；4xx，5xx为错误状态)；实际环境中使用较多，因为网站业务适合运行在k8s集群环境上。
tcpSocket: 测试某个端口是否可以连接；实际环境中使用较少，端口正常无法代表服务正常。

3. 核心参数

initialDelaySeconds

初始化探针启动间隔时间：等待Pod处于running状态后的n秒开始启动探针；防止因业务启动时间较长而造成的健康检查失败，以及尽而导致的死循环。因此initialDelaySeconds设置的时长一定要大于Pod内业务完全启动的所需的时间；
periodSeconds

探针执行周期：探针执行的时间间隔；
timeoutSeconds

探针检查超时时间：探针执行等待结果的最大时间，超过门限值，则视为失败。默认值为1。
successThreshold

探针检查成功阈值：探针执行检查成功多少次，即为检测成功。默认值为1。
failureThreshold

探针检查失败阈值：探针执行检查失败多少次，即为检测失败。默认值为3。

4. livenessProbe

exec

apiVersion: v1
kind: Pod
metadata:
  name: exec-liveness
spec:
  containers:
    - name: nginx
      image: 10.0.0.140:5000/nginx:1.13
      ports:
        - containerPort: 80
      args:
        - /bin/sh
        - -c
        - touch /tmp/healthy; sleep 30; rm -rf /tmp/healthy; sleep 600;
      livenessProbe:
        exec:
          command:
            - cat
            - /tmp/healthy
        initialDelaySeconds: 5 
        periodSeconds: 5 
        timeoutSeconds: 3 
        successThreshold: 1 
        failureThreshold: 3

[root@k8s-master ~/k8s_yaml/tomcat+mysql]# mkdir ~/k8s_yaml/healthy && cd ../healthy
[root@k8s-master ~/k8s_yaml/healthy]# cat liveness-exec.yaml 
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 create -f liveness-exec.yaml 
pod "exec-liveness" created

[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 describe pod exec-liveness | tail -5

  1m    17s 2   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal  Pulled  Container image "10.0.0.140:5000/nginx:1.13" already present on machine
  17s   17s 1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal  Killing Killing container with docker id ca8c9ba97501: pod "exec-liveness_default(800f963c-e2c1-11eb-9de1-000c29870b5c)" container "nginx" is unhealthy, it will be killed and re-created.
  17s   17s 1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal  Created Created container with docker id c30a501185be; Security:[seccomp=unconfined]
  17s   17s 1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal  Started Started container with docker id c30a501185be
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 get pod
NAME                    READY     STATUS             RESTARTS   AGE
exec-liveness           0/1       CrashLoopBackOff   17         53m
httpget-liveness        1/1       Running            1          36m
test-2416581181-9fqr6   2/2       Running            22         236d
test-2416581181-jzl5l   2/2       Running            22         236d

httpGet

apiVersion: v1
kind: Pod
metadata:
  name: httpget-liveness
spec:
  containers:
    - name: nginx
      image: 10.0.0.140:5000/nginx:1.13
      ports:
        - containerPort: 80
      livenessProbe:
        httpGet:
          path: /index.html
          port: 80  
        initialDelaySeconds: 5
        periodSeconds: 5

[root@k8s-master ~/k8s_yaml/healthy]# cat liveness-httpget.yaml 
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 create -f  liveness-httpget.yaml 
pod "httpget-liveness" created
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 describe pod httpget-liveness | grep Liveness
    Liveness:           http-get http://:80/index.html delay=5s timeout=1s period=5s #success=1 #failure=3  #默认阈值
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 describe pod httpget-liveness | tail -4
  33m       33m     1   {default-scheduler }                Normal      Scheduled   Successfully assigned httpget-liveness to 10.0.0.120
  33m       33m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Pulled      Container image "10.0.0.140:5000/nginx:1.13" already present on machine
  33m       33m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Created     Created container with docker id 102651b9f1c4; Security:[seccomp=unconfined]
  33m       33m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Started     Started container with docker id 102651b9f1c4
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 exec -it 102651b9f1c4 /bin/bash
Error from server (NotFound): pods "102651b9f1c4" not found
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 exec -it httpget-liveness /bin/bash
root@httpget-liveness:/# rm -f  /usr/share/nginx/html/index.html 
root@httpget-liveness:/# exit
exit
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 describe pod httpget-liveness | tail -4
  22s       12s     3   {kubelet 10.0.0.120}    spec.containers{nginx}  Warning     Unhealthy   Liveness probe failed: HTTP probe failed with statuscode: 404
  12s       12s     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Killing     Killing container with docker id 102651b9f1c4: pod "httpget-liveness_default(f81d0b80-e2c3-11eb-9de1-000c29870b5c)" container "nginx" is unhealthy, it will be killed and re-created.
  12s       12s     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Created     Created container with docker id 7cca27d50894; Security:[seccomp=unconfined]
  12s       12s     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Started     Started container with docker id 7cca27d50894

tcpSocket

apiVersion: v1
kind: Pod
metadata:
  name: tcpsocket-liveness
spec:
  containers:
    - name: nginx
      image: 10.0.0.140:5000/nginx:1.13
      ports:
        - containerPort: 80
      args:
        - /bin/bash
        - -c 
        - tail -f /etc/hosts
      livenessProbe:
        tcpSocket:
          port: 80
        initialDelaySeconds: 10
        periodSeconds: 3

[root@k8s-master ~/k8s_yaml/healthy]# cat liveness-socket.yml 
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 create -f liveness-socket.yml 
pod "tcpsocket-liveness" created
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  exec -it tcpsocket-liveness /bin/bash
root@tcpsocket-liveness:/# service nginx start
root@tcpsocket-liveness:/# 
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 describe pod httpget-liveness | tail -4
  39m       39m     3   {kubelet 10.0.0.120}    spec.containers{nginx}  Warning     Unhealthy   Liveness probe failed: HTTP probe failed with statuscode: 404
  39m       39m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Killing     Killing container with docker id 102651b9f1c4: pod "httpget-liveness_default(f81d0b80-e2c3-11eb-9de1-000c29870b5c)" container "nginx" is unhealthy, it will be killed and re-created.
  39m       39m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Created     Created container with docker id 7cca27d50894; Security:[seccomp=unconfined]
  39m       39m     1   {kubelet 10.0.0.120}    spec.containers{nginx}  Normal      Started     Started container with docker id 7cca27d50894

5. readinessProbe

httpGet

apiVersion: extensions/v1beta1
kind: Deployment
metadata: 
  name: httpget-readiness
spec:
  replicas: 4
  template:
    metadata:
      labels:
        app: nginx
    spec: 
      containers:
      - name: nginx
        image: 10.0.0.140:5000/nginx:1.13
        ports:
        - containerPort: 80
        readinessProbe:
          httpGet:
            path: /Young.html
            port: 80
          initialDelaySeconds: 5
          periodSeconds: 3
          timeoutSeconds: 1

[root@k8s-master ~/k8s_yaml/healthy]# cat readiness-httpGet.yml
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000 create  -f readiness-httpGet.yml 
deployment "httpget-readiness" created
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  get deployment 
NAME                DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
httpget-readiness   4         4         4            0           1m
test                2         2         2            2           236d
[root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  get pod | grep readiness
httpget-readiness-1081103140-bg527   0/1       Running   0          1m
httpget-readiness-1081103140-npwbw   0/1       Running   0          1m
httpget-readiness-1081103140-qk0m8   0/1       Running   0          1m
httpget-readiness-1081103140-w9986   0/1       Running   0          1m

  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  exec -it httpget-readiness-1081103140-bg527 /bin/bash
  root@httpget-readiness-1081103140-bg527:/# echo "Testing 123" >/usr/share/nginx/html/Young.html
  root@httpget-readiness-1081103140-bg527:/# exit
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  exec -it httpget-readiness-1081103140-npwbw /bin/bash
  root@httpget-readiness-1081103140-npwbw:/# echo "Testing 123" >/usr/share/nginx/html/Young.html
  root@httpget-readiness-1081103140-npwbw:/# exit
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  get deployment 
  NAME                DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
  httpget-readiness   4         4         4            2           5m
  test                2         2         2            2           236d
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  get pod -o wide| grep readiness
  httpget-readiness-1081103140-bg527   1/1       Running   0          7m        192.168.45.6   10.0.0.130
  httpget-readiness-1081103140-npwbw   1/1       Running   0          7m        192.168.56.8   10.0.0.120
  httpget-readiness-1081103140-qk0m8   0/1       Running   0          7m        192.168.45.7   10.0.0.130
  httpget-readiness-1081103140-w9986   0/1       Running   0          7m        192.168.56.9   10.0.0.120
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  expose deploy httpget-readiness --port=80 --name=
  readiness-httpget-svc
  service "readiness-httpget-svc" exposed
  [root@k8s-master ~/k8s_yaml/healthy]# kubectl -s http://10.0.0.110:10000  describe svc readiness-httpget-svc 
  Name:         readiness-httpget-svc
  Namespace:        default
  Labels:           app=nginx
  Selector:     app=nginx
  Type:         ClusterIP
  IP:           10.100.243.225
  Port:          80/TCP
  Endpoints:        192.168.45.6:80,192.168.56.8:80
  Session Affinity: None
  No events.

四、 Dashboard服务

Dashboard服务镜像文件
提取码：3lhv

step 1 上传并导入镜像

[root@k8s-registry ~]# rz -E
rz waiting to receive.
[root@k8s-registry ~]# ls kubernetes-dashboard-amd64_v1.4.1.tar.gz 
kubernetes-dashboard-amd64_v1.4.1.tar.gz
[root@k8s-registry ~]# docker load -i kubernetes-dashboard-amd64_v1.4.1.tar.gz 
5f70bf18a086: Loading layer 1.024 kB/1.024 kB
2e350fa8cbdf: Loading layer 86.96 MB/86.96 MB
Loaded image: index.tenxcloud.com/google_containers/kubernetes-dashboard-amd64:v1.4.1

step 2 为镜像设置标签

[root@k8s-registry ~]# docker tag index.tenxcloud.com/google_containers/kubernetes-dashboard-amd64:v1.4.1 10.0.0.140:5000/kubernetes-dashboard-amd64:v1.4.1
[root@k8s-registry ~]# docker push 10.0.0.140:5000/kubernetes-dashboard-amd64:v1.4.1
The push refers to a repository [10.0.0.140:5000/kubernetes-dashboard-amd64]
5f70bf18a086: Mounted from kubedns-amd64 
2e350fa8cbdf: Pushed 
v1.4.1: digest: sha256:e446d645ff6e6b3147205c58258c2fb431105dc46998e4d742957623bf028014 size: 1147

step 3 创建dashboard配置文件并应用

# Dashboard服务Deployment资源
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
# Keep the name in sync with image version and
# gce/coreos/kube-manifests/addons/dashboard counterparts
  name: kubernetes-dashboard-latest
  namespace: kube-system
spec:
  replicas: 1
  template:
    metadata:
      labels:
        k8s-app: kubernetes-dashboard
        version: latest
        kubernetes.io/cluster-service: "true"
    spec:
      containers:
      - name: kubernetes-dashboard
        image: 10.0.0.140:5000/kubernetes-dashboard-amd64:v1.4.1
        resources:
          # keep request = limit to keep this container in guaranteed class
          limits:
            cpu: 100m
            memory: 50Mi
          requests:
            cpu: 100m
            memory: 50Mi
        ports:
        - containerPort: 9090
        args:
         -  --apiserver-host=http://10.0.0.110:10000
        livenessProbe:
          httpGet:
            path: /
            port: 9090
          initialDelaySeconds: 30
          timeoutSeconds: 30

# Dashboard服务Service资源
apiVersion: v1
kind: Service
metadata:
  name: kubernetes-dashboard
  namespace: kube-system
  labels:
    k8s-app: kubernetes-dashboard
    kubernetes.io/cluster-service: "true"
spec:
  selector:
    k8s-app: kubernetes-dashboard
  ports:
  - port: 80
    targetPort: 9090

[root@k8s-master ~/k8s_yaml/healthy]# mkdir ../dashboard && cd ../dashboard
[root@k8s-master ~/k8s_yaml/dashboard]# cat dashboard.yaml 
[root@k8s-master ~/k8s_yaml/dashboard]# cat dashboard-svc.yaml 
[root@k8s-master ~/k8s_yaml/dashboard]# kubectl -s http://10.0.0.110:10000 create -f .
service "kubernetes-dashboard" created
deployment "kubernetes-dashboard-latest" created
[root@k8s-master ~/k8s_yaml/dashboard]# kubectl -s http://10.0.0.110:10000 get all -n kube-system
NAME                                 DESIRED   CURRENT   UP-TO-DATE   AVAILABLE   AGE
deploy/kube-dns                      2         2         2            2           237d
deploy/kubernetes-dashboard-latest   1         1         1            1           1m

NAME                       CLUSTER-IP       EXTERNAL-IP   PORT(S)         AGE
svc/kube-dns               10.100.1.1       <none>        53/UDP,53/TCP   237d
svc/kubernetes-dashboard   10.100.154.244   <none>        80/TCP          1m

NAME                                        DESIRED   CURRENT   READY     AGE
rs/kube-dns-2134347918                      2         2         2         237d
rs/kubernetes-dashboard-latest-2686154000   1         1         1         1m

NAME                                              READY     STATUS    RESTARTS   AGE
po/kube-dns-2134347918-d78jc                      4/4       Running   44         237d
po/kube-dns-2134347918-nvd49                      4/4       Running   44         237d
po/kubernetes-dashboard-latest-2686154000-11380   1/1       Running   0          1m

step 4 访问[ http://IP:Port/ui/ ]

IP为kube-apiserver服务所在主机的IP地址，Port为kube-apiserver服务所占用主机端口

通过apiServer反向代理访问Service:
http://aprServer的IP地址/api/v1/proxy/namespaces/nameSpace名称/services/service名称
附：常用于访问type类型为ClusterIP的svc资源

一、 DNS服务

1. 安装DNS服务

2. 修改kubelet参数

3. 验证DNS服务

二、 namespace

三、 健康检查

1. 探针的种类

2. 探针的检测方法

3. 核心参数

4. livenessProbe

5. readinessProbe

四、 Dashboard服务

三、健康检查