一、Pod 资源管理
1.1、resource 的定义
容器运行过程中需要分配所需的资源，如何与 cggroup 联动配合呢？答案是通过定义resource来实现资源的分配，资源的分配单位主要是 cpu 和 memory，资源的定义分两种：requests 和 limits，requests 表示请求资源，主要用于初始 kubernetes 调度 pod 时的依据，表示必须满足的分配资源；limits 表示资源的限制，即 pod 不能超过 limits 定义的限制大小，超过则通过 cggroup 限制，pod 中定义资源可以通过下面四个字段定义：
- spec.container[].resources.requests.cpu 请求cpu资源的大小，如0.1个cpu和100m表示分配1/10个cpu；
- spec.container[].resources.requests.memory 请求内存大小，单位可用M，Mi，G，Gi表示；
- spec.container[].resources.limits.cpu 限制cpu的大小，不能超过阀值，cggroup中限制的值；
- spec.container[].resources.limits.memory 限制内存的大小，不能超过阀值，超过会发生OOM；
1、如何定义 pod 的 resource 资源
以定义nginx-demo 为例，容器请求 cpu 资源为 250m，限制为 500m，请求内存资源为 128Mi，限制内存资源为 256Mi，当然也可以定义多个容器的资源，多个容器相加就是 pod 的资源总资源，如下：
[root@node-1 demo]#cat nginx-resource.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-demo
labels:
name: nginx-demo
spec:
containers:
- name: nginx-demo
image: nginx:1.7.9
imagePullPolicy: IfNotPresent
ports:
- name: nginx-port-80
protocol: TCP
containerPort: 80
resources:
requests:
cpu: 0.25
memory: 128Mi
limits:
cpu: 500m
memory: 256Mi
2、pod 的配置定义
如之前的pod还存在，先将其删除 kubectl delete pod
[root@node-1 demo]# kubectl apply -f nginx-resource.yaml
pod/nginx-demo created
3、查看 pod 资源的分配详情
[root@node-1 demo]# kubectl get pods
NAME READY STATUS RESTARTS AGE
demo-7b86696648-8bq7h 1/1 Running 0 12d
demo-7b86696648-8qp46 1/1 Running 0 12d
demo-7b86696648-d6hfw 1/1 Running 0 12d
nginx-demo 1/1 Running 0 94s
[root@node-1 demo]# kubectl describe pods nginx-demo
Name: nginx-demo
Namespace: default
Priority: 0
Node: node-3/10.254.100.103
Start Time: Sat, 28 Sep 2019 12:10:49 +0800
Labels: name=nginx-demo
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"name":"nginx-demo"},"name":"nginx-demo","namespace":"default"},"sp...
Status: Running
IP: 10.244.2.13
Containers:
nginx-demo:
Container ID: docker://55d28fdc992331c5c58a51154cd072cd6ae37e03e05ae829a97129f85eb5ed79
Image: nginx:1.7.9
Image ID: docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Sat, 28 Sep 2019 12:10:51 +0800
Ready: True
Restart Count: 0
Limits: #限制资源
cpu: 500m
memory: 256Mi
Requests: #请求资源
cpu: 250m
memory: 128Mi
Environment: <none>
...省略...
4、Pod 的资源如何分配呢？
毫无疑问是从 node 上分配的，当我们创建一个 pod 的时候如果设置了 requests，kubernetes 的调度器 kube-scheduler 会执行两个调度过程：filter 过滤和 weight 称重，kube-scheduler 会根据请求的资源过滤，把符合条件的 node 筛选出来，然后再进行排序，把最满足运行 pod 的 node 筛选出来，然后再特定的 node 上运行 pod。调度算法和细节可以参考下 kubernetes 调度算法介绍。如下是 node-3 节点资源的分配详情：
[root@node-1 ~]# kubectl describe node node-3
...省略...
Capacity: #节点上资源的总资源情况，1个cpu，2g内存，110个pod
cpu: 1
ephemeral-storage: 51473888Ki
hugepages-2Mi: 0
memory: 1882352Ki
pods: 110
Allocatable: #节点容许分配的资源情况，部分预留的资源会排出在Allocatable范畴
cpu: 1
ephemeral-storage: 47438335103
hugepages-2Mi: 0
memory: 1779952Ki
pods: 110
System Info:
Machine ID: 0ea734564f9a4e2881b866b82d679dfc
System UUID: FFCD2939-1BF2-4200-B4FD-8822EBFFF904
Boot ID: 293f49fd-8a7c-49e2-8945-7a4addbd88ca
Kernel Version: 3.10.0-957.21.3.el7.x86_64
OS Image: CentOS Linux 7 (Core)
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://18.6.3
Kubelet Version: v1.15.3
Kube-Proxy Version: v1.15.3
PodCIDR: 10.244.2.0/24
Non-terminated Pods: (3 in total) #节点上运行pod的资源的情况，除了nginx-demo之外还有多个pod
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
default nginx-demo 250m (25%) 500m (50%) 128Mi (7%) 256Mi (14%) 63m
kube-system kube-flannel-ds-amd64-jp594 100m (10%) 100m (10%) 50Mi (2%) 50Mi (2%) 14d
kube-system kube-proxy-mh2gq 0 (0%) 0 (0%) 0 (0%) 0 (0%) 12d
Allocated resources: #已经分配的cpu和memory的资源情况
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 350m (35%) 600m (60%)
memory 178Mi (10%) 306Mi (17%)
ephemeral-storage 0 (0%) 0 (0%)
Events: <none>
1.2、资源分配原理
Pod的定义的资源 requests 和 limits 作用于 kubernetes 的调度器 kube-sheduler 上，实际上 cpu 和内存定义的资源会应用在 container 上，通过容器上的 cggroup 实现资源的隔离作用，接下来我们介绍下资源分配的原理。
- spec.containers[].resources.requests.cpu 作用在CpuShares，表示分配cpu 的权重，争抢时的分配比例
- spec.containers[].resources.requests.memory 主要用于kube-scheduler调度器，对容器没有设置意义
- spec.containers[].resources.limits.cpu 作用CpuQuota和CpuPeriod，单位为微秒，计算方法为：CpuQuota/CpuPeriod，表示最大cpu最大可使用的百分比，如500m表示允许使用1个cpu中的50%资源
- spec.containers[].resources.limits.memory 作用在Memory，表示容器最大可用内存大小，超过则会OOM
以上面定义的 nginx-demo 为例，研究下 pod 中定义的 requests 和 limits 应用在 docker 生效的参数：
1、查看 pod 所在的 node 节点，nginx-demo 调度到 node-3 节点上
[root@node-1 ~]# kubectl get pods -o wide nginx-demo
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-demo 1/1 Running 0 96m 10.244.2.13 node-3 <none> <none>
2、获取容器的 id 号
可以通过 kubectl describe pods nginx-demo 的 containerID 获取到容器的 id，或者登陆到 node-3 节点通过名称过滤获取到容器的 id 号，默认会有两个 pod：一个通过 pause 镜像创建，另外一个通过应用镜像创建。
[root@node-3 ~]# docker container list |grep nginx
55d28fdc9923 84581e99d807 "nginx -g 'daemon of…" 2 hours ago Up 2 hours k8s_nginx-demonginx-demo_default_66958ef7-507a-41cd-a688-7a4976c6a71e_0
2fe0498ea9b5 k8s.gcr.io/pause:3.1 "/pause" 2 hours ago Up 2 hours k8s_POD_nginx-demo_default_66958ef7-507a-41cd-a688-7a4976c6a71e_0
3、查看docker容器详情信息
[root@node-3 ~]# docker container inspect 55d28fdc9923
[
...部分输出省略...
{
"Image": "sha256:84581e99d807a703c9c03bd1a31cd9621815155ac72a7365fd02311264512656",
"ResolvConfPath": "/var/lib/docker/containers/2fe0498ea9b5dfe1eb63eba09b1598a8dfd60ef046562525da4dcf7903a25250/resolv.conf",
"HostConfig": {
"Binds": [
"/var/lib/kubelet/pods/66958ef7-507a-41cd-a688-7a4976c6a71e/volumes/kubernetes.io~secret/default-token-5qwmc:/var/run/secrets/kubernetes.io/serviceaccount:ro",
"/var/lib/kubelet/pods/66958ef7-507a-41cd-a688-7a4976c6a71e/etc-hosts:/etc/hosts",
"/var/lib/kubelet/pods/66958ef7-507a-41cd-a688-7a4976c6a71e/containers/nginx-demo/1cc072ca:/dev/termination-log"
],
"ContainerIDFile": "",
"LogConfig": {
"Type": "json-file",
"Config": {
"max-size": "100m"
}
},
"UTSMode": "",
"UsernsMode": "",
"ShmSize": 67108864,
"Runtime": "runc",
"ConsoleSize": [
0,
0
],
"Isolation": "",
"CpuShares": 256, CPU分配的权重，作用在requests.cpu上
"Memory": 268435456, 内存分配的大小，作用在limits.memory上
"NanoCpus": 0,
"CgroupParent": "kubepods-burstable-pod66958ef7_507a_41cd_a688_7a4976c6a71e.slice",
"BlkioWeight": 0,
"BlkioWeightDevice": null,
"BlkioDeviceReadBps": null,
"BlkioDeviceWriteBps": null,
"BlkioDeviceReadIOps": null,
"BlkioDeviceWriteIOps": null,
"CpuPeriod": 100000, CPU分配的使用比例，和CpuQuota一起作用在limits.cpu上
"CpuQuota": 50000,
"CpuRealtimePeriod": 0,
"CpuRealtimeRuntime": 0,
"CpusetCpus": "",
"CpusetMems": "",
"Devices": [],
"DeviceCgroupRules": null,
"DiskQuota": 0,
"KernelMemory": 0,
"MemoryReservation": 0,
"MemorySwap": 268435456,
"MemorySwappiness": null,
"OomKillDisable": false,
"PidsLimit": 0,
"Ulimits": null,
"CpuCount": 0,
"CpuPercent": 0,
"IOMaximumIOps": 0,
"IOMaximumBandwidth": 0,
},
}
]
1.3、CPU 资源测试
pod中 cpu 的限制主要通过 requests.cpu 和 limits.cpu 来定义，limits 是不能超过的 cpu 大小，我们通过 stress 镜像来验证，stress 是一个c pu 和 内存 的压侧工具，通过指定 args 参数的定义压侧 cpu 的大小。监控 pod 的 cpu 和内存可通过 kubectl top 的方式来查看，依赖于监控组件如 metric-server 或 promethus，当前没有安装，我们通过 docker stats 的方式来查看。
1、通过 stress 镜像定义一个 pod，分配 0.25 个 cores 和最大限制 0.5 个core使用比例
[root@node-1 demo]# cat cpu-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: cpu-demo
namespace: default
annotations:
kubernetes.io/description: "demo for cpu requests and"
spec:
containers:
- name: stress-cpu
image: vish/stress
resources:
requests:
cpu: 250m
limits:
cpu: 500m
args:
- -cpus
- "1"
2、应用 yaml 文件生成 pod
[root@node-1 demo]# kubectl apply -f cpu-demo.yaml
pod/cpu-demo created
3、查看 pod 资源分配详情
[root@node-1 demo]# kubectl describe pods cpu-demo
Name: cpu-demo
Namespace: default
Priority: 0
Node: node-2/10.254.100.102
Start Time: Sat, 28 Sep 2019 14:33:12 +0800
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{"kubernetes.io/description":"demo for cpu requests and"},"name":"cpu-demo","nam...
kubernetes.io/description: demo for cpu requests and
Status: Running
IP: 10.244.1.14
Containers:
stress-cpu:
Container ID: docker://14f93767ad37b92beb91e3792678f60c9987bbad3290ae8c29c35a2a80101836
Image: progrium/stress
Image ID: docker-pullable://progrium/stress@sha256:e34d56d60f5caae79333cee395aae93b74791d50e3841986420d23c2ee4697bf
Port: <none>
Host Port: <none>
Args:
-cpus
1
State: Waiting
Reason: CrashLoopBackOff
Last State: Terminated
Reason: Error
Exit Code: 1
Started: Sat, 28 Sep 2019 14:34:28 +0800
Finished: Sat, 28 Sep 2019 14:34:28 +0800
Ready: False
Restart Count: 3
Limits: #cpu限制使用的比例
cpu: 500m
Requests: #cpu请求的大小
cpu: 250m
4、查看容器资源使用情况
登陆到特定的 node 节点，通过 docker container stats 查看容器的资源使用详情
limits.cpu 资源使用率，在 pod 所属的 node 上通过 top 查看，cpu 的使用率限制百分比为 50%。
limits.cpu 验证，宿主机上 top 查看 cpu 资源的使用率。通过上面的验证可以得出结论，我们在 stress 容器中定义使用 1 个 core，通过 limits.cpu 限定可使用的 cpu 大小是 500m，测试验证 pod 的资源已在容器内部或宿主机上都严格限制在 50%（node 机器上只有一个 cpu，如果有 2 个 cpu 则会分摊为 25%）。
1.4、memory资源测试
1、通过 stress 镜像测试验证 requests.memory 和 limits.memory 的生效范围
limits.memory定义容器可使用的内存资源大小，当超过内存设定的大小后容器会发生OOM，如下定义一个测试的容器，最大内存不能超过512M,使用stress镜像--vm-bytes定义压侧内存大小为256Mi
[root@node-1 demo]# cat memory-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: memory-stress-demo
annotations:
kubernetes.io/description: "stress demo for memory limits"
spec:
containers:
- name: memory-stress-limits
image: polinux/stress
resources:
requests:
memory: 128Mi
limits:
memory: 512Mi
command: ["stress"]
args: ["--vm", "1", "--vm-bytes", "256M", "--vm-hang", "1"]
2、应用 yaml 文件生成 pod
[root@node-1 demo]# kubectl apply -f memory-demo.yaml
pod/memory-stress-demo created
[root@node-1 demo]# kubectl get pods memory-stress-demo -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
memory-stress-demo 1/1 Running 0 41s 10.244.1.19 node-2 <none> <none>
3、查看资源的分配情况
[root@node-1 demo]# kubectl describe pods memory-stress-demo
Name: memory-stress-demo
Namespace: default
Priority: 0
Node: node-2/10.254.100.102
Start Time: Sat, 28 Sep 2019 15:13:06 +0800
Labels: <none>
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{"kubernetes.io/description":"stress demo for memory limits"},"name":"memory-str...
kubernetes.io/description: stress demo for memory limits
Status: Running
IP: 10.244.1.16
Containers:
memory-stress-limits:
Container ID: docker://c7408329cffab2f10dd860e50df87bd8671e65a0f8abb4dae96d059c0cb6bb2d
Image: polinux/stress
Image ID: docker-pullable://polinux/stress@sha256:6d1825288ddb6b3cec8d3ac8a488c8ec2449334512ecb938483fc2b25cbbdb9a
Port: <none>
Host Port: <none>
Command:
stress
Args:
--vm
1
--vm-bytes
256Mi
--vm-hang
1
State: Waiting
Reason: CrashLoopBackOff
Last State: Terminated
Reason: Error
Exit Code: 1
Started: Sat, 28 Sep 2019 15:14:08 +0800
Finished: Sat, 28 Sep 2019 15:14:08 +0800
Ready: False
Restart Count: 3
Limits: #内存限制大小
memory: 512Mi
Requests: #内存请求大小
memory: 128Mi
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-5qwmc (ro)
4、查看容器内存资源的使用情况
分配256M 内存，最大可使用为 512Mi，利用率为 50%，此时没有超过 limits 限制的大小，容器运行正常
5、当容器内部超过内存的大小会怎么样呢？
我们将--vm-byte设置为513M，容器会尝试运行，超过内存后会OOM，kube-controller-manager会不停的尝试重启容器,RESTARTS的次数会不停的增加。
[root@node-1 demo]# cat memory-demo.yaml
apiVersion: v1
kind: Pod
metadata:
name: memory-stress-demo
annotations:
kubernetes.io/description: "stress demo for memory limits"
spec:
containers:
- name: memory-stress-limits
image: polinux/stress
resources:
requests:
memory: 128Mi
limits:
memory: 512Mi
command: ["stress"]
args: ["--vm", "1", "--vm-bytes", "520M", "--vm-hang", "1"] . #容器中使用内存为520M
查看容器的状态为OOMKilled，RESTARTS的次数不断的增加，不停的尝试重启
[root@node-1 demo]# kubectl get pods memory-stress-demo
NAME READY STATUS RESTARTS AGE
memory-stress-demo 0/1 OOMKilled 3 60s
二、Pod 服务质量
服务质量 QOS（Quality of Service）主要用于 pod 调度和驱逐时参考的重要因素，不同的 QOS 其服务质量不同，对应不同的优先级，主要分为三种类型的 Qos：
- BestEffort 尽最大努力分配资源，默认没有指定 resource 分配的 Qos，优先级最低；
- Burstable 可波动的资源，至少需要分配到 requests 中的资源，常见的 QOS；
- Guaranteed 完全可保障资源，requests 和 limits 定义的资源相同，优先级最高。
2.1、BestEffort 最大努力
1、默认的 Qos 策略为 BestEffort
Pod中没有定义 resource，默认的 Qos 策略为 BestEffort,优先级别最低，当资源比较进展是需要驱逐 evice 时，优先驱逐 BestEffort 定义的 Pod，如下定义一个 BestEffort 的 Pod
[root@node-1 demo]# cat nginx-qos-besteffort.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-qos-besteffort
labels:
name: nginx-qos-besteffort
spec:
containers:
- name: nginx-qos-besteffort
image: nginx:1.7.9
imagePullPolicy: IfNotPresent
ports:
- name: nginx-port-80
protocol: TCP
containerPort: 80
resources: {}
2、创建 pod 并查看 Qos 策略，qosClass 为 BestEffort
[root@node-1 demo]# kubectl apply -f nginx-qos-besteffort.yaml
pod/nginx-qos-besteffort created
查看Qos策略
[root@node-1 demo]# kubectl get pods nginx-qos-besteffort -o yaml
apiVersion: v1
kind: Pod
metadata:
annotations:
kubectl.kubernetes.io/last-applied-configuration: |
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"name":"nginx-qos-besteffort"},"name":"nginx-qos-besteffort","namespace":"default"},"spec":{"containers":[{"image":"nginx:1.7.9","imagePullPolicy":"IfNotPresent","name":"nginx-qos-besteffort","ports":[{"containerPort":80,"name":"nginx-port-80","protocol":"TCP"}],"resources":{}}]}}
creationTimestamp: "2019-09-28T11:12:03Z"
labels:
name: nginx-qos-besteffort
name: nginx-qos-besteffort
namespace: default
resourceVersion: "1802411"
selfLink: /api/v1/namespaces/default/pods/nginx-qos-besteffort
uid: 56e4a2d5-8645-485d-9362-fe76aad76e74
spec:
containers:
- image: nginx:1.7.9
imagePullPolicy: IfNotPresent
name: nginx-qos-besteffort
ports:
- containerPort: 80
name: nginx-port-80
protocol: TCP
resources: {}
terminationMessagePath: /dev/termination-log
...省略...
status:
hostIP: 10.254.100.102
phase: Running
podIP: 10.244.1.21
qosClass: BestEffort #Qos策略
startTime: "2019-09-28T11:12:03Z"
3、删除测试 Pod
[root@node-1 demo]# kubectl delete pods nginx-qos-besteffort
pod "nginx-qos-besteffort" deleted
2.2、Burstable可波动
1、Pod 的服务质量为 Burstable，仅次于 Guaranteed 的服务质量，至少需要一个 container 定义了 requests，且 requests 定义的资源小于 limits 资源
[root@node-1 demo]# cat nginx-qos-burstable.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-qos-burstable
labels:
name: nginx-qos-burstable
spec:
containers:
- name: nginx-qos-burstable
image: nginx:1.7.9
imagePullPolicy: IfNotPresent
ports:
- name: nginx-port-80
protocol: TCP
containerPort: 80
resources:
requests:
cpu: 100m
memory: 128Mi
limits:
cpu: 200m
memory: 256Mi
2、应用 yaml 文件生成 pod 并查看 Qos 类型
[root@node-1 demo]# kubectl apply -f nginx-qos-burstable.yaml
pod/nginx-qos-burstable created
查看Qos类型
[root@node-1 demo]# kubectl describe pods nginx-qos-burstable
Name: nginx-qos-burstable
Namespace: default
Priority: 0
Node: node-2/10.254.100.102
Start Time: Sat, 28 Sep 2019 19:27:37 +0800
Labels: name=nginx-qos-burstable
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"name":"nginx-qos-burstable"},"name":"nginx-qos-burstable","namespa...
Status: Running
IP: 10.244.1.22
Containers:
nginx-qos-burstable:
Container ID: docker://d1324b3953ba6e572bfc63244d4040fee047ed70138b5a4bad033899e818562f
Image: nginx:1.7.9
Image ID: docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Sat, 28 Sep 2019 19:27:39 +0800
Ready: True
Restart Count: 0
Limits:
cpu: 200m
memory: 256Mi
Requests:
cpu: 100m
memory: 128Mi
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-5qwmc (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-5qwmc:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-5qwmc
Optional: false
QoS Class: Burstable #服务质量是可波动的Burstable
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 95s default-scheduler Successfully assigned default/nginx-qos-burstable to node-2
Normal Pulled 94s kubelet, node-2 Container image "nginx:1.7.9" already present on machine
Normal Created 94s kubelet, node-2 Created container nginx-qos-burstable
Normal Started 93s kubelet, node-2 Started container nginx-qos-burstable
2.3、Guaranteed 完全保障
1、requests.cpu 和 limits.cpu 相同
resource 中定义的 cpu 和 memory 必须包含有 requests 和 limits，切 requests 和 limits 的值必须相同，其优先级别最高，当出现调度和驱逐时优先保障该类型的 Qos,如下定义一个nginx-qos-guaranteed 的容器，requests.cpu 和 limits.cpu 相同，同理 requests.memory 和 limits.memory.
[root@node-1 demo]# cat nginx-qos-guaranteed.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx-qos-guaranteed
labels:
name: nginx-qos-guaranteed
spec:
containers:
- name: nginx-qos-guaranteed
image: nginx:1.7.9
imagePullPolicy: IfNotPresent
ports:
- name: nginx-port-80
protocol: TCP
containerPort: 80
resources:
requests:
cpu: 200m
memory: 256Mi
limits:
cpu: 200m
memory: 256Mi
2、应用 yaml 文件生成 pod 并查看 pod 的 Qos 类型为可完全保障 Guaranteed
[root@node-1 demo]# kubectl apply -f nginx-qos-guaranteed.yaml
pod/nginx-qos-guaranteed created
[root@node-1 demo]# kubectl describe pods nginx-qos-guaranteed
Name: nginx-qos-guaranteed
Namespace: default
Priority: 0
Node: node-2/10.254.100.102
Start Time: Sat, 28 Sep 2019 19:37:15 +0800
Labels: name=nginx-qos-guaranteed
Annotations: kubectl.kubernetes.io/last-applied-configuration:
{"apiVersion":"v1","kind":"Pod","metadata":{"annotations":{},"labels":{"name":"nginx-qos-guaranteed"},"name":"nginx-qos-guaranteed","names...
Status: Running
IP: 10.244.1.23
Containers:
nginx-qos-guaranteed:
Container ID: docker://cf533e0e331f49db4e9effb0fbb9249834721f8dba369d281c8047542b9f032c
Image: nginx:1.7.9
Image ID: docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Sat, 28 Sep 2019 19:37:16 +0800
Ready: True
Restart Count: 0
Limits:
cpu: 200m
memory: 256Mi
Requests:
cpu: 200m
memory: 256Mi
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-5qwmc (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-5qwmc:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-5qwmc
Optional: false
QoS Class: Guaranteed #服务质量为可完全保障Guaranteed
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute for 300s
node.kubernetes.io/unreachable:NoExecute for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 25s default-scheduler Successfully assigned default/nginx-qos-guaranteed to node-2
Normal Pulled 24s kubelet, node-2 Container image "nginx:1.7.9" already present on machine
Normal Created 24s kubelet, node-2 Created container nginx-qos-guaranteed
Normal Started 24s kubelet, node-2 Started container nginx-qos-guaranteed
三、总结
关于resource有节点使用建议：
- requests和limits资源定义推荐不超过1:2，避免分配过多资源而出现资源争抢，发生OOM；
- pod中默认没有定义resource，推荐给namespace定义一个limitrange，确保pod能分到资源；
- 防止node上资源过度而出现机器hang住或者OOM，建议node上设置保留和驱逐资源，如保留资源--system-reserved=cpu=200m,memory=1G，驱逐条件--eviction hard=memory.available`<500Mi。
四、附录
容器计算资源管理：
https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/
pod内存资源管理：
https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/
podcpu资源管理：
https://kubernetes.io/docs/tasks/configure-pod-container/assign-cpu-resource/
服务质量QOS：
https://kubernetes.io/docs/tasks/configure-pod-container/quality-service-pod/
Docker关于CPU的限制：
https://www.cnblogs.com/sparkdev/p/8052522.html
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