k8s 之资源限制以及探针检查

当定义Pod每个容器所需的资源数量可以有选择地设置。最常见的可设置资源是CPU以及内存大小和其他类型的资源。

当为Pod指定了中容器request在资源方面，调度器决定使用该信息Pod调度到哪个节点。当容器也被指定时limit资源时，kubelet它将确保运行容器不会超过设定的容器limit资源量。kubelet还将为容器预留设置的容器request容器使用的资源量。 如果Pod节点有足够的可用资源，容器可以使用超过设置的request资源量。但是，超过设置的容器不能使用limit资源量。 如果给容器设置了内存limit值，但未设置内存request值，Kubernetes它将自动设置和内存limit相匹配的request值。类似地，如果设置了给容器CPU的limit值但未设置CPU的request值，则Kubernetes自动设置CPU的request值，并使之和CPU的limit值匹配。

https://kubernetes.io/zh/docs/concepts/configuration/manage-resources-containers/

在创建容器时时预分配的定义CPU资源 spec.containers[].resources.requests.cpu 在创建容器时时预分配的定义内存资源 spec.containers[].resources.requests.memory 在创建容器时时预分配的定义巨页资源 spec.containers[].resources.requests.hugepages-<size> 定义cpu的资源上限 spec.containers[].resources.limits.cpu 定义内存资源的上限 spec.containers[].resoures.limits.memory
定义巨页的资源上限
spec.containers[].resources.limits.hugepages-<size>

CPU资源的request和limit以cpu为单位。kubernetes中的一个cpu相当于1个vCPU（1个超线程）。 Kubernetes也支持带小数CPU的请求。spec.containers[].resources.requests.cpu为0.5的容器能够获得一个cpu的一半CPU资源（类似于cgroup对CPU资源的时间分片）。表达式0.1等价于表达式100m（毫核），表示每1000毫秒内容器可以使用的CPU时间总量为0.1*1000毫秒。

内存的request和limit以字节为单位。可以用证书表示， 也可以用以10为底数的指数的单位（E、P、T、G、M、K）来表示， 或者以2为底数的指数的单位（Ei、Pi、Ti、Gi、Mi、Ki）来表示。 如1KB=103=1000，1MB=106=1000000=1000KB，1GB=10^9=1000000000=1000MB 1KiB=210=1024，1MiB=220=1048576=1024KiB

PS：在买硬盘的时候，操作系统报的数量要比产品标出或商家号称的小一些，主要原因是标出的是以MB、GB为单位的，1GB就是1,000,000,000Byte，而操作系统是以2进制为处理单位的，因此检查硬盘容量时是以MiB、GiB为单位，1GiB=2^30=1,073,741,824Byte。相比较而言，1GiB要比1GB多出73,741,824Byte，所以检测实际结果要比标出的少一些，单位越大，两者的差值也就越大。

apiVersion: v1
kind: Pod
metadata:
  name: frontend
spec:
  containers:
  - name: app
    image: images.my-company.example/app:v4
    env:
    - name: MYSQL_ROOT_PASSWORD
      value: "password"
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
  - name: log-aggregator
    image: images.my-company.example/log-aggregator:v6
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"

此例子中 Pod 有两个 Container。每个 Container 的请求为 0.25 cpu 和 64MiB（226 字节）内存， 每个容器的资源约束为 0.5 cpu 和 128MiB 内存。 你可以认为该 Pod 的资源请求为 0.5 cpu 和 128 MiB 内存，资源限制为 1 cpu 和 256MiB 内存。

[root@master ~]# mkdir /opt/test
[root@master ~]# cd !$
cd /opt/test
[root@master test]# vim test1.yaml
 
apiVersion: v1
kind: Pod
metadata:
  name: test1
spec:
  containers:
  - name: web
    image: nginx
    env:
    - name: WEB_ROOT_PASSWORD
      value: "password"
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"
  - name: db
    image: mysql
    env:
    - name: MYSQL_ROOT_PASSWORD
      value: "password"
    resources:
      requests:
        memory: "64Mi"
        cpu: "250m"
      limits:
        memory: "128Mi"
        cpu: "500m"

由于mysql对于内存的使用要求比较高，因此需要先检查内存的可用空间是否能够满足mysql的正常运行，若剩余内存不够，可对其进行释放操作。

free -mH

[root@node01 ~]# free -mh
              total        used        free      shared  buff/cache   available
Mem:           1.9G        1.0G         86M         26M        870M        663M
Swap:            0B          0B          0B

内存总量为1.9G，实际使用1G，因此可有内存应该为0.9G左右。 但是由于有870M的内存被用于缓存，导致了free仅为86M。 86M剩余可用内存显然是不够用的，因此需要释放缓存。

echo [1\2\3] > /proc/sys/vm/drop_caches

[root@node01 ~]# cat /proc/sys/vm/drop_caches
0
[root@node01 ~]# echo 3 > /proc/sys/vm/drop_caches
[root@node01 ~]# free -mh
              total        used        free      shared  buff/cache   available
Mem:           1.9G        968M        770M         26M        245M        754M
Swap:            0B          0B          0B

0：0是系统默认值，默认情况下表示不释放内存，由操作系统自动管理 1：释放页缓存 2：释放dentries和inodes 3：释放所有缓存 注意： 如果因为是应用有像内存泄露、溢出的问题，从swap的使用情况是可以比较快速可以判断的，但free上面反而比较难查看。相反，如果在这个时候，我们告诉用户，修改系统的一个值，“可以”释放内存，free就大了。用户会怎么想？不会觉得操作系统“有问题”吗？所以说，既然核心是可以快速清空buffer或cache，也不难做到（这从上面的操作中可以明显看到），但核心并没有这样做（默认值是0），我们就不应该随便去改变它。 一般情况下，应用在系统上稳定运行了，free值也会保持在一个稳定值的，虽然看上去可能比较小。当发生内存不足、应用获取不到可用内存、OOM错误等问题时，还是更应该去分析应用方面的原因，如用户量太大导致内存不足、发生应用内存溢出等情况，否则，清空buffer，强制腾出free的大小，可能只是把问题给暂时屏蔽了。

kubectl apply -f tets1.yaml

[root@master test]# kubectl apply -f test1.yaml 
pod/test1 created

kubectl get pod -o wide -w

[root@master test]# kubectl get pod -o wide -w
NAME    READY   STATUS              RESTARTS   AGE   IP       NODE     NOMINATED NODE   READINESS GATES
test1   0/2     ContainerCreating   0          4s    <none>   node01   <none>           <none>
test1   2/2     Running             0          18s   10.244.1.55   node01   <none>           <none>
test1   1/2     OOMKilled           0          21s   10.244.1.55   node01   <none>           <none>
test1   2/2     Running             1          37s   10.244.1.55   node01   <none>           <none>
test1   1/2     OOMKilled           1          40s   10.244.1.55   node01   <none>           <none>
......

OOM（OverOfMemory）表示服务的运行超过了我们所设定的约束值。 Ready:2/2，status:Running说明该pod已成功创建并运行，但运行过程中发生OOM问题被kubelet杀死并重新拉起新的pod。

kubectl logs test1 -c web

[root@master test]# kubectl logs test1 -c web
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
2021/11/06 08:31:23 [notice] 1#1: using the "epoll" event method
2021/11/06 08:31:23 [notice] 1#1: nginx/1.21.3
2021/11/06 08:31:23 [notice] 1#1: built by gcc 8.3.0 (Debian 8.3.0-6) 
2021/11/06 08:31:23 [notice] 1#1: OS: Linux 3.10.0-693.el7.x86_64
2021/11/06 08:31:23 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
2021/11/06 08:31:23 [notice] 1#1: start worker processes
2021/11/06 08:31:23 [notice] 1#1: start worker process 31
2021/11/06 08:31:23 [notice] 1#1: start worker process 32

nginx启动正常，接下来查看mysql日志 kubectl logs test1 -c mysql

[root@master test]# kubectl logs test1 -c db2021-11-06 08:38:44+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.27-1debian10 started.2021-11-06 08:38:44+00:00 [Note] [Entrypoint]: Switching to dedicated user 'mysql'2021-11-06 08:38:44+00:00 [Note] [Entrypoint]: Entrypoint script for MySQL Server 8.0.27-1debian10 started.2021-11-06 08:38:44+00:00 [Note] [Entrypoint]: Initializing database files2021-11-06T08:38:44.274783Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.27) initializing of server in progress as process 412021-11-06T08:38:44.279965Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.2021-11-06T08:38:44.711420Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.2021-11-06T08:38:45.777355Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1 is enabled for channel mysql_main2021-11-06T08:38:45.777389Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1.1 is enabled for channel mysql_main2021-11-06T08:38:45.898121Z 6 [Warning] [MY-010453] [Server] root@localhost is created with an empty password ! Please consider switching off the --initialize-insecure option./usr/local/bin/docker-entrypoint.sh: line 191:    41 Killed                  "$@" --initialize-insecure --default-time-zone=SYSTEM

kubectl delete -f test1

[root@master test]# kubectl delete -f test1.yaml pod "test1" deleted

[root@master test]# vim test1.yaml apiVersion: v1kind: Podmetadata: name: test1spec: containers: - name: web image: nginx env: - name: WEB_ROOT_PASSWORD value: "password" resources: requests: memory: "64Mi" cpu: "250m" limits: memory: "128Mi" cpu: "500m" - name: db image: mysql env: - name: MYSQL_ROOT_PASSWORD value: "password" resources: requests: memory: "512Mi" cpu: "0.5" limits: memory: "1024Mi" cpu: "1"

kubectl apply -f test1.yaml

[root@master test]# kubectl apply -f test1.yaml pod/test1 created

kubectl get pod -o wide -w

[root@master test]# kubectl get pod -o wide -wNAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATEStest1 0/2 ContainerCreating 0 12s <none> node01 <none> <none>test1 2/2 Running 0 18s 10.244.1.56 node01 <none> <none>

kubectl describe pod test1

[root@master test]# kubectl describe pod test1......Containers: web: Container ID: docker://caf5bef54f878ebba32728b5e43743e36bbdf1457973f3ca130c98de5e1803d3 Image: nginx......#nginx资源限制 Limits: cpu: 500m memory: 128Mi Requests: cpu: 250m memory: 64Mi#nginx环境变量 Environment: WEB_ROOT_PASSWORD: password Mounts: /var/run/secrets/kubernetes.io/serviceaccount from default-token-7lsdx (ro) db: Container ID: docker://2574f2bd02d9d7fc5bb0d2b74582b0bece3d8bd37d1d7ff3148ae8109df49367 Image: mysql......#mysql资源限制 Limits: cpu: 1 memory: 1Gi Requests: cpu: 500m memory: 512Mi#mysql环境变量 Environment: MYSQL_ROOT_PASSWORD: password Mounts: /var/run/secrets/kubernetes.io/serviceaccount from default-token-7lsdx (ro)......#pod创建过程/事件记录Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 105s default-scheduler Successfully assigned default/test1 to node01 Normal Pulling 104s kubelet, node01 Pulling image "nginx" Normal Pulled 103s kubelet, node01 Successfully pulled image "nginx" Normal Created 103s kubelet, node01 Created container web Normal Started 103s kubelet, node01 Started container web Normal Pulling 103s kubelet, node01 Pulling image "mysql" Normal Pulled 88s kubelet, node01 Successfully pulled image "mysql" Normal Created 88s kubelet, node01 Created container db Normal Started 88s kubelet, node01 Started container db

[root@master test]# kubectl describe node node01......  Namespace                  Name                           CPU Requests  CPU Limits   Memory Requests  Memory Limits  AGE  ---------                  ----                           ------------  ----------   ---------------  -------------  ---  default                    test1                          750m (37%)    1500m (75%)  576Mi (30%)      1152Mi (61%)   10m  kube-system                coredns-bccdc95cf-qrlbp        100m (5%)     0 (0%)       70Mi (3%)        170Mi (9%)     4d21h  kube-system                kube-flannel-ds-amd64-6927f    100m (5%)     100m (5%)    50Mi (2%)        50Mi (2%)      4d21h  kube-system                kube-proxy-hjqfc               0 (0%)        0 (0%)       0 (0%)           0 (0%)         4d21hAllocated resources:  (Total limits may be over 100 percent, i.e., overcommitted.)  Resource           Requests     Limits  --------           --------     ------  cpu                950m (47%)   1600m (80%)  memory             696Mi (36%)  1372Mi (72%)  ephemeral-storage  0 (0%)       0 (0%)Events:              <none>

node01的配置为2C2G。 CPU Requests分析： nginx的requests为250m，mysql的requests为500m，因此node01的CPU Requests为750m，在node01的两个核中使用占比为37%。 CPU Limits分析： nginx到的limit为500m，mysql的limit为1，因此node01到的CPU Limits为1500m，在node01的两个核中使用占比为75%。 Memory Requests分析： nginx的requests为64Mi，mysql的requests为512Mi，因此node01的内存Requests为576Mi，在node01的2G内存中使用占比为30%。 Memory Limits分析： nginx的limits为128Mi，mysql的limit为1Gi，因此node01的1152Mi，在node01的2G内存中使用占比为61%。

健康检查又称为探针（Probe），是由kubelet对容器执行的定期诊断。

判断容器是否正在运行。如果探测失败，则kubelet会杀死容器，并且容器将根据restartPolicy来设置Pod状态，如果容器不提供存活探针，则默认状态为Success。

判断容器是否准备好接受请求。如果探测失败，端点控制器将从与Pod匹配的所有service endpoints中剔除删除该Pod的IP地址。初始延迟之前的就绪状态默认为Failure。如果容器不提供就绪探针，则默认状态为Success。

判断容器内的应用程序是否已启动，主要针对于不能确定具体启动时间的应用。如果匹配了startupProbe探测，则在startupProbe状态为Success之前，其他所有探针都处于无效状态，直到它成功后其他探针才起作用。如果startupProbe失败，kubelet将杀死容器，容器将根据restartPolicy来重启。如果容器没有配置startupProbe，则默认状态为Success。

以上三种规则可同时定义。在readinessProbe检测成功之前，Pod的running状态是不会变成ready状态的。

在容器内执行执行命令，如果容器退出时返回码为0则认为诊断成功。

对指定端口上的容器的IP地址进行TCP检查（三次握手）。如果端口打开，则诊断被认为是成功的。

对指定的端口和路径上的容器的IP地址执行httpGet请求。如果响应的状态码大于等于200且小于400（2xx和3xx），则诊断被认为是成功的。

每次探测都将获得以下三种结果之一： ● 成功：容器通过了诊断 ● 失败：容器未通过诊断 ● 未知：诊断失败，因此不会采取任何行动

文档链接： https://kubernetes.io/zh/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

apiVersion: v1kind: Podmetadata:  labels:    test: liveness name: liveness-execspec:  containers:  - name: liveness image: k8s.gcr.io/busybox 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

[root@master test]# vim exec.yaml apiVersion: v1kind: Podmetadata: name: liveness-exec namespace: defaultspec: containers: - name: liveness-exec-container image: busybox imagePullPolicy: IfNotPresent command: ["/bin/sh","-c","touch /tmp/live; sleep 30; rm -rf /tmp/live; sleep 3600"] livenessProbe: exec: command: ["test","-e","/tmp/live"] initialDelaySeconds: 1 periodSeconds: 3

在这个配置文件中，可以看到Pod只有一个容器。 容器中的command字段表示创建一个/tmp/live文件后休眠30秒，休眠结束后删除该文件，并休眠10分钟。 仅使用livenessProbe存活探针，并使用exec检查方式，对/tmp/live文件进行存活检测。 initialDelaySeconds字段表示kubelet在执行第一次探测前应该等待1秒。 periodSeconds字段表示kubelet每隔3秒执行一次存活探测。

kubectl create -f exec.yaml

[root@master test]# kubectl create -f exec.yamlpod/liveness-exec created

kubectl get pod -o wide -w

[root@master ~]# kubectl get pod -o wide -wliveness-exec 0/1 Pending 0 0s <none> <none> <none> <none>liveness-exec 0/1 Pending 0 0s <none> node01 <none> <none>liveness-exec 0/1 ContainerCreating 0 0s <none> node01 <none> <none>liveness-exec 1/1 Running 0 2s 10.244.1.62 node01 <none> <none>liveness-exec 1/1 Running 1 68s 10.244.1.62 node01 <none> <none>

发现68秒时容器重启

kubectl describe pod liveness-exec

[root@master test]# kubectl describe pod liveness-exec ......Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 67s default-scheduler Successfully assigned default/liveness-exec to node01 Normal Started 66s kubelet, node01 Started container liveness-exec-container Warning Unhealthy 30s (x3 over 36s) kubelet, node01 Liveness probe failed: Normal Killing 30s kubelet, node01 Container liveness-exec-container failed liveness probe, will be restarted Normal Pulled 0s (x2 over 67s) kubelet, node01 Container image "busybox" already present on machine Normal Created 0s (x2 over 67s) kubelet, node01 Created container liveness-exec-container

在容器启动37秒时，健康检查三次失败（倒推第一次检查在31秒），kubelet启动了killing程序并在67秒时拉取镜像创建新的容器，在68秒时完成第一次容器重启

apiVersion: v1kind: Podmetadata:  labels:    test: liveness name: liveness-httpspec:  containers:  - name: liveness image: k8s.gcr.io/liveness args:    - /server livenessProbe:      httpGet:        path: /healthz port: 8080 httpHeaders:        - name: Custom-Header value: Awesome initialDelaySeconds: 3 periodSeconds: 3

在这个配置文件中，可以看到Pod只有一个容器。initialDealySeconds字段告诉kubelet再执行第一次探测前应该等待3秒。preiodSeconds字段指定了kubelet每隔3秒执行一次存活探测。kubelet会向容器内运行的服务（服务会监听8080端口）发送一个认为容器是健康存活的。如果处理程序返回失败代码，则kubelet会杀死这个容器并且重新启动它。 任何大于或等于200并且小于400的返回代码标示成功，其他返回代码都标示失败。

[root@master test]# vim httpget.yaml apiVersion: v1kind: Podmetadata: name: liveness-httpget namespace: defaultspec: containers: - name: liveness-httpget-container image: nginx imagePullPolicy: IfNotPresent ports: - name: nginx containerPort: 80 livenessProbe: httpGet: port: nginx path: /index.html initialDelaySeconds: 1 periodSeconds: 3 timeoutSeconds: 10

kubectl create -f httpget.yaml

[root@master test]# kubectl create -f httpget.yaml pod/liveness-httpget created

kubectl get pod

[root@master test]# kubectl get podNAME READY STATUS RESTARTS AGEliveness-httpget 1/1 Running 0 6s

kubectl exec -it liveness-httpget – rm -rf /usr/share/nginx/html/index.html

[root@master test]# kubectl exec -it liveness-httpget -- rm -rf /usr/share/nginx/html/index.html

kubectl get pod -w

[root@master test]# kubectl get pod -wNAME READY STATUS RESTARTS AGEliveness-httpget 1/1 Running 0 5m35sliveness-httpget 1/1 Running 1 5m37s

容器发生重启

kubectl describe pod liveness-httpget

[root@master ~]# kubectl describe pod liveness-httpget......Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 5m47s default-scheduler Successfully assigned default/liveness-httpget to node01 Normal Pulled 11s (x2 over 5m46s) kubelet, node01 Container image "nginx" already present on machine Normal Created 11s (x2 over 5m46s) kubelet, node01 Created container liveness-httpget-container Normal Started 11s (x2 over 5m46s) kubelet, node01 Started container liveness-httpget-container Warning Unhealthy 11s (x3 over 17s) kubelet, node01 Liveness probe failed: HTTP probe failed with statuscode: 404 Normal Killing 11s kubelet, node01 Container liveness-httpget-container failed liveness probe, will be restarted

重启原因是HTTP探测得到的状态返回码是404，HTTP probe failed with statuscode: 404。 重启完成后，不会再次重启，因为重新拉取的镜像中包含了index.html文件。

apiVersion: v1kind: Podmetadata:  name: goproxy labels:    app: goproxyspec:  containers:  - name: goproxy image: k8s.gcr.io/goproxy:0.1 ports:    - containerPort: 8080 readinessProbe:      tcpSocket:        port: 8080 initialDelaySeconds: 5 periodSeconds: 10 livenessProbe:      tcpSocket:        port: 8080 initialDelaySeconds: 15 periodSeconds: 20

这个例子同时使用readinessProbe和livenessProbe探测。kubelet会在容器启动5秒后发送第一个readiness探测。这会尝试连接goproxy容器的8080端口。如果探测成功，kubelet将继续每隔10秒运行一次检测。除了readinessProbe探测，这个配置包括了一个livenessProbe探测。kubelet会在容器启动15秒后进行第一次livenessProbe探测。就像readinessProbe探测一样，会尝试连接goproxy容器的8080端口。如果livenessProbe探测失败，这个容器会被重新启动。

[root@master test]# vim tcpsocket.yaml apiVersion: v1kind: Podmetadata: name: liveness-tcpsocketspec: containers: - name: liveness-tcpsocket-container image: nginx livenessProbe: initialDelaySeconds: 5 timeoutSeconds: 1 tcpSocket: port: 8080 periodSeconds: 3

kubectl apply -f tcpsocket.yaml

[root@master test]# kubectl apply -f tcpsocket.yaml pod/liveness-tcpsocket created

kubectl get pod -w

[root@master test]# kubectl get pod -wNAME READY STATUS RESTARTS AGEliveness-tcpsocket 0/1 ContainerCreating 0 6sliveness-tcpsocket 1/1 Running 0 17sliveness-tcpsocket 1/1 Running 1 44sliveness-tcpsocket 1/1 Running 2 71s

pod异常重启

kubectl describe pod liveness-tcpsocket

[root@master test]# kubectl describe pod liveness-tcpsocket ......Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 93s default-scheduler Successfully assigned default/liveness-tcpsocket to node01 Normal Pulled 23s (x3 over 77s) kubelet, node01 Successfully pulled image "nginx" Normal Created 23s (x3 over 77s) kubelet, node01 Created container liveness-tcpsocket-container Normal Started 23s (x3 over 77s) kubelet, node01 Started container liveness-tcpsocket-container Normal Pulling 11s (x4 over 92s) kubelet, node01 Pulling image "nginx" Warning Unhealthy 11s (x9 over 71s) kubelet, node01 Liveness probe failed: dial tcp 10.244.1.65:8080: connect: connection refused Normal Killing 11s (x3 over 65s) kubelet, node01 Container liveness-tcpsocket-container failed liveness probe, will be restarted

重启原因是nginx使用的默认端口为80，8080端口的健康检查被拒绝访问

kubectl delete -f tcpsocket.yaml

[root@master test]# vim tcpsocket.yaml apiVersion: v1kind: Podmetadata: name: liveness-tcpsocketspec: containers: - name: liveness-tcpsocket-container image: nginx livenessProbe: initialDelaySeconds: 5 timeoutSeconds: 1 tcpSocket:#修改端口为80 port: 80 periodSeconds: 3

kubectl apply -f tcpsocket.yaml

[root@master test]# kubectl apply -f tcpsocket.yaml pod/liveness-tcpsocket created

kubectl get pod -o wide -w

[root@master ~]# kubectl get pod -o wide -wNAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATESliveness-tcpsocket 1/1 Running 0 21s 10.244.1.66 node01 <none> <none>

启动正常，并未出现重启

kubectl describe pod liveness-tcpsocket

[root@master test]# kubectl describe pod liveness-tcpsocket ......Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 33s default-scheduler Successfully assigned default/liveness-tcpsocket to node01 Normal Pulling 32s kubelet, node01 Pulling image "nginx" Normal Pulled 17s kubelet, node01 Successfully pulled image "nginx" Normal Created 17s kubelet, node01 Created container liveness-tcpsocket-container Normal Started 17s kubelet, node01 Started container liveness-tcpsocket-container

启动正常

[root@master test]# vim readiness-httpget.yaml apiVersion: v1kind: Podmetadata: name: readiness-httpget namespace: defaultspec: containers: - name: readiness-httpget-container image: nginx imagePullPolicy: IfNotPresent ports: - name: http containerPort: 80 readinessProbe: httpGet: port: 80#注意，这里设置个错误地址 path: /index1.html initialDelaySeconds: 1 periodSeconds: 3 livenessProbe: httpGet: port: http path: /index.html initialDelaySeconds: 1 periodSeconds: 3 timeoutSeconds: 10

kubectl apply -f readiness-httpget.yaml

[root@master test]# kubectl apply -f readiness-httpget.yamlpod/readiness-httpget created

kubectl get pod

[root@master test]# kubectl get podNAME READY STATUS RESTARTS AGEreadiness-httpget 0/1 Running 0 25s

STATUS为Running，但无法进入READY状态

kubectl describe pod readiness-httpget

[root@master test]# kubectl describe pod readiness-httpget......Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Scheduled 119s default-scheduler Successfully assigned default/readiness-httpget to node01 Normal Pulled 119s kubelet, node01 Container image "nginx" already present on machine Normal Created 119s kubelet, node01 Created container readiness-httpget-container Normal Started 119s kubelet, node01 Started container readiness-httpget-container Warning Unhealthy 54s (x22 over 117s) kubelet, node01 Readiness probe failed: HTTP probe failed with statuscode: 404

异常原因为readinessProbe检测的状态返回值为404，kubelet阻止pod进入READY状态

kubectl logs readiness-httpget

[root@master test]# kubectl logs readiness-httpget......2021/11/07 16:40:41 [error] 32#32: *164 open() "/usr/share/nginx/html/index1.html" failed (2: No such file or directory), client: 10.244.1.1, server: localhost, request: "GET /index1.html HTTP/1.1", host: "10.244.1.68:80"10.244.1.1 - - [07/Nov/2021:16:40:41 +0000] "GET /index1.html HTTP/1.1" 404 153 "-" "kube-probe/1.15" "-"10.244.1.1 - - [07/Nov/2021:16:40:43 +0000] "GET /index.html HTTP/1.1" 200 615 "-" "kube-probe/1.15" "-"

kubectl exec -it readiness-httpget – touch /usr/share/nginx/html/index1.html

[root@master test]# kubectl exec -it readiness-httpget -- touch /usr/share/nginx/html/index1.html

kubectl get pod

[root@master test]# kubectl get podNAME READY STATUS RESTARTS AGEreadiness-httpget 1/1 Running 0 15m

[root@master test]# cat readiness-multi-nginx.yaml apiVersion: v1kind: Podmetadata: name: nginx1 labels: app: nginxspec: containers: - name: nginx image: nginx imagePullPolicy: IfNotPresent ports: - name: http containerPort: 80 readinessProbe: httpGet: port: http path: /index.html initialDelaySeconds: 5 periodSeconds: 5 timeoutSeconds: 10---apiVersion: v1kind: Podmetadata: name: nginx2 labels: app: nginxspec: containers: - name: nginx image: nginx imagePullPolicy: IfNotPresent ports: - name: http containerPort: 80 readinessProbe: httpGet: port: http path: /index.html initialDelaySeconds: 5 periodSeconds: 5 timeoutSeconds: 10---apiVersion: v1kind: Podmetadata: name: nginx3 labels: app: nginxspec: containers: - name: nginx image: nginx imagePullPolicy: IfNotPresent ports: - name: http containerPort: 80 readinessProbe: httpGet: port: http path: /index.html initialDelaySeconds: 5 periodSeconds: 5 timeoutSeconds: 10---apiVersion: v1kind: Servicemetadata: name: nginx-svcspec:#service通过selector绑定到nginx集群中 selector: app: nginx type: ClusterIP ports: - name: http port: 80 targetPort: 80

kubectl apply -f readiness-multi-nginx.yaml

[root@master test]# kubectl apply -f readiness-multi-nginx.yamlpod/nginx1 createdpod/nginx2 createdpod/nginx3 createdservice/nginx-svc created