当定义Pod时可以选择性地为每个容器设定所需要的资源数量。最常见的可设定资源是CPU和内存大小,以及其他类型的资源。
当为Pod中的容器指定了request资源时,调度器就使用该信息来决定将Pod调度到哪个节点上。当还为容器指定了limit资源时,kubelet就会确保运行的容器不会使用超出所设的limit资源量。kubelet还会为容器预留所设的request资源量,供该容器使用。
如果Pod所在的节点具有足够的可用资源,容器可以使用超过所设置的request资源量。不过,容器不可以使用超出所设置的limit资源量。
如果给容器设置了内存的limit值,但未设置内存的request值,Kubernetes会自动为其设置与内存limit相匹配的request值。类似的,如果给容器设置了CPU的limit值但未设置CPU的request值,则Kubernetes自动为其设置CPU的request值,并使之与CPU的limit值匹配。
https://kubernetes.io/zh/docs/concepts/configuration/manage-resources-containers/
定义创建容器时预分配的CPU资源
spec.containers[].resources.requests.cpu
定义创建容器时预分配的内存资源
spec.containers[].resources.requests.memory
定义创建容器时预分配的巨页资源
spec.containers[].resources.requests.hugepages-
定义cpu的资源上限
spec.containers[].resources.limits.cpu
定义内存的资源上限
spec.containers[].resources.limits.memory
定义巨页的资源上限
spec.containers[].resources.limits.hugepages-
CPU 和内存都是资源类型。每种资源类型具有其基本单位。 CPU 表达的是计算处理能力,其单位是 Kubernetes CPUs。 内存的单位是字节。 如果你使用的是 Kubernetes v1.14 或更高版本,则可以指定巨页(Huge Page)资源。 巨页是 Linux 特有的功能,节点内核在其中分配的内存块比默认页大小大得多。
例如,在默认页面大小为 4KiB 的系统上,你可以指定约束 hugepages-2Mi: 80Mi。 如果容器尝试分配 40 个 2MiB 大小的巨页(总共 80 MiB ),则分配请求会失败。
说明:
你不能过量使用 hugepages- * 资源。 这与 memory 和 cpu 资源不同。
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
test1 2/2 Running 0 18s 10.244.1.55 node01
test1 1/2 OOMKilled 0 21s 10.244.1.55 node01
test1 2/2 Running 1 37s 10.244.1.55 node01
test1 1/2 OOMKilled 1 40s 10.244.1.55 node01
……
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 db
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]: 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 files
2021-11-06T08:38:44.274783Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.27) initializing of server in progress as process 41
2021-11-06T08:38:44.279965Z 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_main
2021-11-06T08:38:45.777389Z 0 [Warning] [MY-013746] [Server] A deprecated TLS version TLSv1.1 is enabled for channel mysql_main
2021-11-06T08:38:45.898121Z 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
锁定问题容器为mysql
kubectl delete -f test1
[root@master test]# kubectl delete -f test1.yaml
pod "test1" deleted
[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: "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 -w
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
test1 0/2 ContainerCreating 0 12s
test1 2/2 Running 0 18s 10.244.1.56 node01
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%) 4d21h
Allocated 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:
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reasy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
apiVersion: v1
kind: Pod
metadata:
labels:
test: liveness
name: liveness-exec
spec:
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
initalDeploySeconds:指定kubelet在执行第一次探测前应该等待5秒,即第一次探测是在容器启动后的第6秒才开始执行。默认是0秒,最小值是0。
periodSeconds:指定了kubelet应该每5秒执行一次存活探测。默认是10秒,最小值是1
补充:
failureThreshold:当探测失败时,Kubernetes将在放弃之前重试的次数。存活探测情况下的放弃就意味着重新启动容器,就绪探测情况下的放弃Pod会被打上未就绪的标签。默认值是3,最小值是1。
timeoutSeconds:探测的超时后等待多少秒。默认值是1秒,最小值是1。(在Kubernetes 1.20版本之前,exec探针会忽略timeoutSeconds,探针会无限期地持续运行,甚至可能超过所配置的限期,直到返回结果为止。)
在这个配置文件中,可以看到 Pod 中只有一个容器。 periodSeconds 字段指定了 kubelet 应该每 5 秒执行一次存活探测。 initialDelaySeconds 字段告诉 kubelet 在执行第一次探测前应该等待 5 秒。 kubelet 在容器内执行命令 cat /tmp/healthy 来进行探测。 如果命令执行成功并且返回值为 0,kubelet 就会认为这个容器是健康存活的。 如果这个命令返回非 0 值,kubelet 会杀死这个容器并重新启动它。
[root@master test]# vim exec.yaml
apiVersion: v1
kind: Pod
metadata:
name: liveness-exec
namespace: default
spec:
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.yaml
pod/liveness-exec created
kubectl get pod -o wide -w
[root@master ~]# kubectl get pod -o wide -w
liveness-exec 0/1 Pending 0 0s
liveness-exec 0/1 Pending 0 0s
liveness-exec 0/1 ContainerCreating 0 0s
liveness-exec 1/1 Running 0 2s 10.244.1.62 node01
liveness-exec 1/1 Running 1 68s 10.244.1.62 node01
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: v1
kind: Pod
metadata:
labels:
test: liveness
name: liveness-http
spec:
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: v1
kind: Pod
metadata:
name: liveness-httpget
namespace: default
spec:
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 pod
NAME READY STATUS RESTARTS AGE
liveness-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 -w
NAME READY STATUS RESTARTS AGE
liveness-httpget 1/1 Running 0 5m35s
liveness-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: v1
kind: Pod
metadata:
name: goproxy
labels:
app: goproxy
spec:
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: v1
kind: Pod
metadata:
name: liveness-tcpsocket
spec:
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 -w
NAME READY STATUS RESTARTS AGE
liveness-tcpsocket 0/1 ContainerCreating 0 6s
liveness-tcpsocket 1/1 Running 0 17s
liveness-tcpsocket 1/1 Running 1 44s
liveness-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: v1
kind: Pod
metadata:
name: liveness-tcpsocket
spec:
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 -w
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
liveness-tcpsocket 1/1 Running 0 21s 10.244.1.66 node01
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: v1
kind: Pod
metadata:
name: readiness-httpget
namespace: default
spec:
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.yaml
pod/readiness-httpget created
kubectl get pod
[root@master test]# kubectl get pod
NAME READY STATUS RESTARTS AGE
readiness-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 pod
NAME READY STATUS RESTARTS AGE
readiness-httpget 1/1 Running 0 15m
[root@master test]# cat readiness-multi-nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx1
labels:
app: nginx
spec:
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: v1
kind: Pod
metadata:
name: nginx2
labels:
app: nginx
spec:
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: v1
kind: Pod
metadata:
name: nginx3
labels:
app: nginx
spec:
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: v1
kind: Service
metadata:
name: nginx-svc
spec:
#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.yaml
pod/nginx1 created
pod/nginx2 created
pod/nginx3 created
service/nginx-svc created
kubectl get pod,svc -o wide
[root@master test]# kubectl get pod,svc -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
pod/nginx1 1/1 Running 0 22s 10.244.1.69 node01
pod/nginx2 1/1 Running 0 22s 10.244.2.31 node02
pod/nginx3 1/1 Running 0 22s 10.244.1.70 node01
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
service/kubernetes ClusterIP 10.1.0.1
service/nginx-svc ClusterIP 10.1.177.18
运行成功
kubectl exec -it nginx1 -- rm -rf /usr/share/nginx/html/index.html
[root@master test]# kubectl exec -it nginx1 -- rm -rf /usr/share/nginx/html/index.html
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
nginx1 1/1 Running 0 3m41s 10.244.1.69 node01
nginx2 1/1 Running 0 3m41s 10.244.2.31 node02
nginx3 1/1 Running 0 3m41s 10.244.1.70 node01
nginx1 0/1 Running 0 3m43s 10.244.1.69 node01
nginx1的READY状态变为0/1
kubectl describe pod nginx1
[root@master test]# kubectl describe pod nginx1
……
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 4m13s default-scheduler Successfully assigned default/nginx1 to node01
Normal Pulled 4m12s kubelet, node01 Container image "nginx" already present on machine
Normal Created 4m12s kubelet, node01 Created container nginx
Normal Started 4m12s kubelet, node01 Started container nginx
Warning Unhealthy 0s (x9 over 40s) kubelet, node01 Readiness probe failed: HTTP probe failed with statuscode: 404
由于httpGet检测到的状态返回码为404,所以readinessProbe失败,kubelet将其设定为noready状态。
kubectl describe svc nginx-svc
[root@master test]# kubectl describe svc nginx-svc
Name: nginx-svc
Namespace: default
Labels:
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"name":"nginx-svc","namespace":"default"},"spec":{"ports":[{"name":"http"…
Selector: app=nginx
Type: ClusterIP
IP: 10.1.177.18
Port: http 80/TCP
TargetPort: 80/TCP
Endpoints: 10.244.1.70:80,10.244.2.31:80
Session Affinity: None
Events:
nginx1被剔除出了service的终端列表
kubectl get endpoints
[root@master test]# kubectl get endpoints
NAME ENDPOINTS AGE
kubernetes 192.168.122.10:6443 3d3h
nginx-svc 10.244.1.70:80,10.244.2.31:80 9m34s
终端中无nginx1
探针分为3种
检查方式分为3种
常用的探针可选参数有4个
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