k8s基础-健康检查机制
探针类型
Execaction该探针在容器内执行任意命令，并检查命令的退出状态码，如果状态码是0，则探测成功，否则重启
TCPSocketAction该探针尝试与容器指定端口建立TCP连接，如果连接成功建立，则探测成功，否则容器重新启动
HTTPGetAction该探针对容器的IP地址执行HTTP GET请求，如果探测器收到响应，并且响应状态码没有错误，则认为探测成功，如果返回一个不是期望的状态码或未响应，则视为失败，容器将会被重新启动
示例
创建一个http get类型的探针
# cat nginx-health.yml
apiVersion: v1
kind: Pod
metadata:
name: nginx-health
spec:
nodeSelector:
server: 'backend'
containers:
- image: nginx:latest
name: nginx-health
ports:
- containerPort: 80
protocol: TCP
livenessProbe:
httpGet:
path: /index.php
port: 80这里我探测了一个并不存在的地址，所以pod在探测失败后肯定会重启 启动该pod，启动成功后查看pod的描述和日志
# kubectl logs -f nginx-health
2019/10/14 08:56:34 [error] 6#6: *1 open() "/usr/share/nginx/html/index.php" failed (2: No such file or directory), client: 192.168.152.168, server: localhost, request: "GET /index.php HTTP/1.1", host: "192.168.166.155:80"
192.168.152.168 - - [14/Oct/2019:08:56:34 +0000] "GET /index.php HTTP/1.1" 404 153 "-" "kube-probe/1.15" "-"看下pod信息
# kubectl describe pod nginx-health
Name: nginx-health
Namespace: default
Priority: 0
Node: node1/192.168.152.168
Start Time: Mon, 14 Oct 2019 04:50:10 -0400
Labels: <none>
Annotations: cni.projectcalico.org/podIP: 192.168.166.155/32
kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"nginx-health","namespace":"default"},"spec":{"containers":[{"image":"...
Status: Running
IP: 192.168.166.155
Containers:
nginx-health:
Container ID: docker://36e07faa8b8d0eb7f3e5465186cc2f23cf8198776d45c546f9ead3264e901c02
Image: nginx:latest
Image ID: docker-pullable://nginx@sha256:aeded0f2a861747f43a01cf1018cf9efe2bdd02afd57d2b11fcc7fcadc16ccd1
Port: 80/TCP
Host Port: 0/TCP
State: Waiting
Reason: CrashLoopBackOff
Last State: Terminated
Reason: Completed
Exit Code: 0
Started: Mon, 14 Oct 2019 05:00:09 -0400
Finished: Mon, 14 Oct 2019 05:00:34 -0400
Ready: False
Restart Count: 7
Liveness: http-get http://:80/index.php delay=0s timeout=1s period=10s #success=1 #failure=3
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-ps4lj (ro)
Conditions:
Type Status
Initialized True
Ready False
ContainersReady False
PodScheduled True
Volumes:
default-token-ps4lj:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-ps4lj
Optional: false
QoS Class: BestEffort
Node-Selectors: server=backend
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 11m default-scheduler Successfully assigned default/nginx-health to node1
Normal Created 9m21s (x3 over 11m) kubelet, node1 Created container nginx-health
Normal Started 9m21s (x3 over 11m) kubelet, node1 Started container nginx-health
Normal Pulling 8m52s (x4 over 11m) kubelet, node1 Pulling image "nginx:latest"
Normal Killing 8m52s (x3 over 10m) kubelet, node1 Container nginx-health failed liveness probe, will be restarted
Normal Pulled 6m3s (x6 over 11m) kubelet, node1 Successfully pulled image "nginx:latest"
Warning Unhealthy 82s (x22 over 10m) kubelet, node1 Liveness probe failed: HTTP probe failed with statuscode: 404可以看到相关报错，从该描述中也可以看到相关信息： delay=0s 表示在容器启动后立即开始探测 timeout=1s 表示容器必须在一秒内进行响应，否则记作失败 period=10s 表示每隔10秒探测一次 failure=3 表示连续三次探测失败后重启容器
现在我们改成一个存在的链接进行探测，然后将以上提到的几个指标修改下，比如等pod启动十秒后再进此探测 我们怎么去查看有哪些指标呢？k8s有相关类似的help
# kubectl explain pods.spec.containers.livenessProbe
KIND: Pod
VERSION: v1
RESOURCE: livenessProbe <Object>
DESCRIPTION:
Periodic probe of container liveness. Container will be restarted if the
probe fails. Cannot be updated. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
Probe describes a health check to be performed against a container to
determine whether it is alive or ready to receive traffic.
FIELDS:
exec <Object>
One and only one of the following should be specified. Exec specifies the
action to take.
failureThreshold <integer>
Minimum consecutive failures for the probe to be considered failed after
having succeeded. Defaults to 3. Minimum value is 1.
httpGet <Object>
HTTPGet specifies the http request to perform.
initialDelaySeconds <integer>
Number of seconds after the container has started before liveness probes
are initiated. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
periodSeconds <integer>
How often (in seconds) to perform the probe. Default to 10 seconds. Minimum
value is 1.
successThreshold <integer>
Minimum consecutive successes for the probe to be considered successful
after having failed. Defaults to 1. Must be 1 for liveness. Minimum value
is 1.
tcpSocket <Object>
TCPSocket specifies an action involving a TCP port. TCP hooks not yet
supported
timeoutSeconds <integer>
Number of seconds after which the probe times out. Defaults to 1 second.
Minimum value is 1. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes修改后的yml文件如下
# cat nginx-health.yml
apiVersion: v1
kind: Pod
metadata:
name: nginx-health
spec:
nodeSelector:
server: 'backend'
containers:
- image: nginx:latest
name: nginx-health
ports:
- containerPort: 80
protocol: TCP
livenessProbe:
httpGet:
path: /index.html
port: 80
initialDelaySeconds: 10
periodSeconds: 10
timeoutSeconds: 10启动后再次查看日志
# kubectl logs -f nginx-health
192.168.152.168 - - [14/Oct/2019:09:03:39 +0000] "GET /index.html HTTP/1.1" 200 612 "-" "kube-probe/1.15" "-"
192.168.152.168 - - [14/Oct/2019:09:03:49 +0000] "GET /index.html HTTP/1.1" 200 612 "-" "kube-probe/1.15" "-"查看修改后的几个指标有没有生效
# kubectl describe pod nginx-health
Name: nginx-health
Namespace: default
Priority: 0
Node: node1/192.168.152.168
Start Time: Mon, 14 Oct 2019 05:17:49 -0400
Labels: <none>
Annotations: cni.projectcalico.org/podIP: 192.168.166.157/32
kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"name":"nginx-health","namespace":"default"},"spec":{"containers":[{"image":"...
Status: Running
IP: 192.168.166.157
Containers:
nginx-health:
Container ID: docker://011be58ccbe6fbc6e490588ec5a1f60028e1593a1f28a59022fda72ff544cffc
Image: nginx:latest
Image ID: docker-pullable://nginx@sha256:aeded0f2a861747f43a01cf1018cf9efe2bdd02afd57d2b11fcc7fcadc16ccd1
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 14 Oct 2019 05:18:18 -0400
Ready: True
Restart Count: 0
Liveness: http-get http://:80/index.html delay=10s timeout=10s period=10s #success=1 #failure=3
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-ps4lj (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-ps4lj:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-ps4lj
Optional: false
QoS Class: BestEffort
Node-Selectors: server=backend
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 67s default-scheduler Successfully assigned default/nginx-health to node1
Normal Pulling 66s kubelet, node1 Pulling image "nginx:latest"
Normal Pulled 38s kubelet, node1 Successfully pulled image "nginx:latest"
Normal Created 38s kubelet, node1 Created container nginx-health
Normal Started 38s kubelet, node1 Started container nginx-health举报
腾讯云开发者
