StartupProbe
k8s 1.16 版本新增的探针，用于判断应用程序是否已经启动了。
当配置了 startupProbe 后，会先禁用其他探针，直到 startupProbe 成功后，其他探针才会继续。
作用：由于有时候不能准确预估应用一定是多长时间启动成功，因此配置另外两种探针时不方便配置初始化时长来检测，而配置了 statupProbe 后，只有在应用启动成功了，才会执行另外两种探针，可以更加方便的结合使用另外两种探针使用。
LivenessProbe
用于探测容器中的应用是否运行，如果探测失败，kubelet 会根据配置的重启策略进行重启，若没有配置，默认就认为容器启动成功，不会执行重启策略。
ReadinessProbe
用于探测容器内的程序是否健康，它的返回值如果返回 success，那么就认为该容器已经完全启动，并且该容器是可以接收外部流量。
探测方式
-
ExecAction
在容器内部执行一个命令，如果命令退出时返回码为 0 则认为诊断成功。
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livenessProbe: exec: command: - cat - /health
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TCPSocketAction
通过 tcp 连接监测容器内端口是否开放，如果端口打开，则诊断被认为是成功的
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livenessProbe: tcpSocket: port: 80 -
HTTPGetAction
生产环境用的较多的方式，发送 HTTP 请求到容器内的应用程序，如果接口返回的状态码在 200~400 之间，则认为容器健康。
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livenessProbe: httpGet: path: /health port: 8080 scheme: HTTP httpHeaders: - name: xxx value: xxx参数配置
- initialDelaySeconds: 60 # 执行第一次探测前的等待时间，单位秒
-
timeoutSeconds: 2 # 超时时间，单位秒
-
periodSeconds: 5 # 监测间隔时间，单位秒
-
successThreshold: 1 # 检查 1 次成功就表示成功
- failureThreshold: 5 # 监测失败 5 次就表示失败
样例
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[root@k8s-master1 test]# vim vito-demo-pod-nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: vito-demo-pod-nginx
labels:
type: app
ver: 1.0.0
namespace: 'default'
spec:
containers:
- name: demo-container-nginx
image: nginx:1.7.9
startupProbe: # 探针类型
httpGet: # 探测方式
path: /index.html
port: 80
timeoutSeconds: 2 # 超时时间
periodSeconds: 5 # 监测间隔时间
successThreshold: 1 # 检查 1 次成功就表示成功
failureThreshold: 5 # 监测失败 5 次就表示失败
livenessProbe:
tcpSocket:
port: 80
timeoutSeconds: 3
periodSeconds: 5
successThreshold: 1
failureThreshold: 5
readinessProbe:
exec:
command:
- sh
- -c
- "sleep 2; echo 'success' > /inited"
timeoutSeconds: 3
periodSeconds: 5
successThreshold: 1
failureThreshold: 5
imagePullPolicy: IfNotPresent
command:
- nginx
- -g
- 'daemon off;'
workingDir: /usr/share/nginx/html
ports:
- name: http
containerPort: 80
protocol: TCP
- name: https
containerPort: 443
env:
- name: JVM_OPTS
value: '-Xms128m -Xmx128m'
resources:
requests:
cpu: 100m
memory: 128Mi
limits:
cpu: 200m
memory: 256Mi
restartPolicy: OnFailure
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[root@k8s-master1 test]# kubectl create -f vito-demo-pod-nginx.yaml
pod/vito-demo-pod-nginx created
[root@k8s-master1 test]# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
vito-demo-pod-nginx 1/1 Running 0 28s 10.244.37.203 k8s-node1.zhch.lan <none> <none>
# kubectl exec -it PodName -c ContainerName -- Command
[root@k8s-master1 test]# kubectl exec -it vito-demo-pod-nginx -c demo-container-nginx -- cat /inited
success
[root@k8s-master1 test]# kubectl describe pod vito-demo-pod-nginx
Name: vito-demo-pod-nginx
Namespace: default
Priority: 0
Service Account: default
Node: k8s-node1.zhch.lan/192.168.99.204
Start Time: Thu, 14 Dec 2023 12:52:27 +0800
Labels: type=app
ver=1.0.0
Annotations: cni.projectcalico.org/containerID: 5b8a4c8ba81121256a2f98bfceaf9f6ddedba09109a9b625fca15eae7be6ed7d
cni.projectcalico.org/podIP: 10.244.37.203/32
cni.projectcalico.org/podIPs: 10.244.37.203/32
Status: Running
IP: 10.244.37.203
IPs:
IP: 10.244.37.203
Containers:
demo-container-nginx:
Container ID: docker://185de3f33bb849efef2eab906c8073e35cdf32ad28869c6138a1bf024c975997
Image: nginx:1.7.9
Image ID: docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
Ports: 80/TCP, 443/TCP
Host Ports: 0/TCP, 0/TCP
Command:
nginx
-g
daemon off;
State: Running
Started: Thu, 14 Dec 2023 12:52:28 +0800
Ready: True
Restart Count: 0
Limits:
cpu: 200m
memory: 256Mi
Requests:
cpu: 100m
memory: 128Mi
Liveness: tcp-socket :80 delay=0s timeout=3s period=5s #success=1 #failure=5
Readiness: exec [sh -c sleep 2; echo 'success' > /inited] delay=0s timeout=3s period=5s #success=1 #failure=5
Startup: http-get http://:80/index.html delay=0s timeout=2s period=5s #success=1 #failure=5
Environment:
JVM_OPTS: -Xms128m -Xmx128m
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-5bllv (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-5bllv:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: Burstable
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 53s default-scheduler Successfully assigned default/vito-demo-pod-nginx to k8s-node1.zhch.lan
Normal Pulled 52s kubelet Container image "nginx:1.7.9" already present on machine
Normal Created 52s kubelet Created container demo-container-nginx
Normal Started 52s kubelet Started container demo-container-nginx
[root@k8s-master1 test]#
