容器探测的具体实现方法；三种探针类型
ExecAction、TCPSocketAction、HTTPGetAction
lifecycle
Actions that the management system should take in response to container
lifecycle events. Cannot be updated.
livenessProbe
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
readinessProbe
Periodic probe of container service readiness. Container will be removed
from service endpoints if the probe fails. Cannot be updated. More info:
https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
livenessProbe 介绍
[root@master manifests]# kubectl explain pods.spec.containers.livenessProbe
KIND: Pod
VERSION: v1
RESOURCE: livenessProbe
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 探针
One and only one of the following should be specified. Exec specifies the
action to take.
failureThreshold 成功次数
Minimum consecutive failures for the probe to be considered failed after
having succeeded. Defaults to 3. Minimum value is 1.
httpGet http探针
HTTPGet specifies the http request to perform.
initialDelaySeconds 启动后等待多长时间，开始探测
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 每一次间隔时间；默认10秒
How often (in seconds) to perform the probe. Default to 10 seconds. Minimum
value is 1.
successThreshold 失败次数
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 tcp探针
TCPSocket specifies an action involving a TCP port. TCP hooks not yet
supported
timeoutSeconds 每一超时时间；默认1秒
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
exec探测方法介绍
[root@master manifests]# kubectl explain pods.spec.containers.livenessProbe.exec
KIND: Pod
VERSION: v1
RESOURCE: exec
DESCRIPTION:
One and only one of the following should be specified. Exec specifies the
action to take.
ExecAction describes a "run in container" action.
FIELDS:
command <[]string> #指定运行的命令，容器里必须支持
Command is the command line to execute inside the container, the working
directory for the command is root ('/') in the container's filesystem. The
command is simply exec'd, it is not run inside a shell, so traditional
shell instructions ('|', etc) won't work. To use a shell, you need to
explicitly call out to that shell. Exit status of 0 is treated as
live/healthy and non-zero is unhealthy.
编写测试
[root@master manifests]# cat chenxi-exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: liveness-exec-pod
namespace: default
spec:
containers:
- name: liveness-exec-container
image: busybox:latest
imagePullPolicy: IfNotPresent
command: ["/bin/sh","-c","touch /tmp/chenxi; sleep 60; rm -rf /tmp/chenxi; sleep 3600"]
livenessProbe:
exec:
command: ["test","-e","/tmp/chenxi"]
initialDelaySeconds: 2
restartPolicy: OnFailure
启动这个pod
[root@master manifests]# kubectl create -f chenxi-exec.yaml
pod/liveness-exec-pod created
测试
[root@master manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
liveness-exec-pod 1/1 Running 0 2m
myapp-84cd4b7f95-g6ldp 1/1 Running 3 10d
nginx-5896f46c8-zblcs 1/1 Running 3 10d
pod-demo 2/2 Running 0 162m
[root@master manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
liveness-exec-pod 1/1 Running 1 2m1s
myapp-84cd4b7f95-g6ldp 1/1 Running 3 10d
nginx-5896f46c8-zblcs 1/1 Running 3 10d
pod-demo 2/2 Running 0 162m
[root@master manifests]# kubectl get pods
NAME READY STATUS RESTARTS AGE
liveness-exec-pod 1/1 Running 1 2m2s
myapp-84cd4b7f95-g6ldp 1/1 Running 3 10d
nginx-5896f46c8-zblcs 1/1 Running 3 10d
pod-demo 2/2 Running 0 162m
容器创建后，终止前操作
[root@master manifests]# kubectl explain pods.spec.containers.lifecycle
KIND: Pod
VERSION: v1
RESOURCE: lifecycle
DESCRIPTION:
Actions that the management system should take in response to container
lifecycle events. Cannot be updated.
Lifecycle describes actions that the management system should take in
response to container lifecycle events. For the PostStart and PreStop
lifecycle handlers, management of the container blocks until the action is
complete, unless the container process fails, in which case the handler is
aborted.
FIELDS:
postStart
PostStart is called immediately after a container is created. If the
handler fails, the container is terminated and restarted according to its
restart policy. Other management of the container blocks until the hook
completes. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
preStop
PreStop is called immediately before a container is terminated due to an
API request or management event such as liveness probe failure, preemption,
resource contention, etc. The handler is not called if the container
crashes or exits. The reason for termination is passed to the handler. The
Pod's termination grace period countdown begins before the PreStop hooked
is executed. Regardless of the outcome of the handler, the container will
eventually terminate within the Pod's termination grace period. Other
management of the container blocks until the hook completes or until the
termination grace period is reached. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
创建后操作
[root@master manifests]# kubectl explain pods.spec.containers.lifecycle.postStart
KIND: Pod
VERSION: v1
RESOURCE: postStart
DESCRIPTION:
PostStart is called immediately after a container is created. If the
handler fails, the container is terminated and restarted according to its
restart policy. Other management of the container blocks until the hook
completes. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
Handler defines a specific action that should be taken
FIELDS:
exec
One and only one of the following should be specified. Exec specifies the
action to take.
httpGet
HTTPGet specifies the http request to perform.
tcpSocket
TCPSocket specifies an action involving a TCP port. TCP hooks not yet
supported
停止前操作
[root@master manifests]# kubectl explain pods.spec.containers.lifecycle.preStop
KIND: Pod
VERSION: v1
RESOURCE: preStop
DESCRIPTION:
PreStop is called immediately before a container is terminated due to an
API request or management event such as liveness probe failure, preemption,
resource contention, etc. The handler is not called if the container
crashes or exits. The reason for termination is passed to the handler. The
Pod's termination grace period countdown begins before the PreStop hooked
is executed. Regardless of the outcome of the handler, the container will
eventually terminate within the Pod's termination grace period. Other
management of the container blocks until the hook completes or until the
termination grace period is reached. More info:
https://kubernetes.io/docs/concepts/containers/container-lifecycle-hooks/#container-hooks
Handler defines a specific action that should be taken
FIELDS:
exec
One and only one of the following should be specified. Exec specifies the
action to take.
httpGet
HTTPGet specifies the http request to perform.
tcpSocket
TCPSocket specifies an action involving a TCP port. TCP hooks not yet
supported
编写podyaml文件
[root@master manifests]# cat pot.yaml
apiVersion: v1
kind: Pod
metadata:
name: poststart-pod
namespace: default
spec:
containers:
- name: busybox-httpd
image: busybox:latest
imagePullPolicy: IfNotPresent
lifecycle:
postStart:
exec:
command: ['/bin/sh','-c','echo Home_Page >> /tmp/index.html']
#command: ['/bin/sh','-c','sleep 3600']
command: ["/bin/httpd"]
args: ["-f","-h /tmp"]
