寫在前面
上一篇文章中kubernetes系列教程（五）深入掌握核心概念pod初步介紹了yaml學習kubernetes中重要的一個概念pod，接下來介紹kubernetes系列教程pod的resource資源管理和pod的Quality of service服務質量。
1. Pod資源管理
1.1 resource定義
容器運行過程中需要分配所需的資源，如何與cggroup聯動配合呢？答案是通過定義resource來實現資源的分配，資源的分配單位主要是cpu和memory，資源的定義分兩種：requests和limits，requests表示請求資源，主要用於初始kubernetes調度pod時的依據，表示必須滿足的分配資源;limits表示資源的限制，即pod不能超過limits定義的限制大小，超過則通過cggroup限制，pod中定義資源可以通過下面四個字段定義：
- spec.container[].resources.requests.cpu 請求cpu資源的大小，如0.1個cpu和100m表示分配1/10個cpu；
- spec.container[].resources.requests.memory 請求內存大小，單位可用M，Mi，G，Gi表示；
- spec.container[].resources.limits.cpu 限制cpu的大小，不能超過閥值，cggroup中限制的值；
- spec.container[].resources.limits.memory 限制內存的大小，不能超過閥值，超過會發生OOM；
1、開始學習如何定義pod的resource資源,如下以定義nginx-demo爲例，容器請求cpu資源爲250m，限制爲500m，請求內存資源爲128Mi，限制內存資源爲256Mi，當然也可以定義多個容器的資源，多個容器相加就是pod的資源總資源，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: 256Mi2、應用pod的配置定義(如之前的pod還存在，先將其刪除kubectl delete pod <pod-name>),或pod命名爲另外一個名
[root@node-1 demo]# kubectl apply -f nginx-resource.yaml
pod/nginx-demo created3、查看pod資源的分配詳情
[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: #限制資源
cpu: 500m
memory: 256Mi
Requests: #請求資源
cpu: 250m
memory: 128Mi
Environment: <none>
...省略...4、Pod的資源如何分配呢？毫無疑問是從node上分配的，當我們創建一個pod的時候如果設置了requests，kubernetes的調度器kube-scheduler會執行兩個調度過程：filter過濾和weight稱重，kube-scheduler會根據請求的資源過濾，把符合條件的node篩選出來，然後再進行排序，把最滿足運行pod的node篩選出來，然後再特定的node上運行pod。調度算法和細節可以參考下kubernetes調度算法介紹。如下是node-3節點資源的分配詳情：
[root@node-1 ~]# kubectl describe node node-3
...省略...
Capacity: #節點上資源的總資源情況，1個cpu，2g內存，110個pod
cpu: 1
ephemeral-storage: 51473888Ki
hugepages-2Mi: 0
memory: 1882352Ki
pods: 110
Allocatable: #節點容許分配的資源情況，部分預留的資源會排出在Allocatable範疇
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) #節點上運行pod的資源的情況，除了nginx-demo之外還有多個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: #已經分配的cpu和memory的資源情況
(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 資源分配原理
Pod的定義的資源requests和limits作用於kubernetes的調度器kube-sheduler上，實際上cpu和內存定義的資源會應用在container上，通過容器上的cggroup實現資源的隔離作用，接下來我們介紹下資源分配的原理。
- spec.containers[].resources.requests.cpu 作用在CpuShares，表示分配cpu 的權重，爭搶時的分配比例
- spec.containers[].resources.requests.memory 主要用於kube-scheduler調度器，對容器沒有設置意義
- spec.containers[].resources.limits.cpu 作用CpuQuota和CpuPeriod，單位爲微秒，計算方法爲：CpuQuota/CpuPeriod，表示最大cpu最大可使用的百分比，如500m表示允許使用1個cpu中的50%資源
- spec.containers[].resources.limits.memory 作用在Memory，表示容器最大可用內存大小，超過則會OOM
以上面定義的nginx-demo爲例，研究下pod中定義的requests和limits應用在docker生效的參數：
1、查看pod所在的node節點，nginx-demo調度到node-3節點上
[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、獲取容器的id號，可以通過kubectl describe pods nginx-demo的containerID獲取到容器的id，或者登陸到node-3節點通過名稱過濾獲取到容器的id號，默認會有兩個pod：一個通過pause鏡像創建，另外一個通過應用鏡像創建
[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_03、查看docker容器詳情信息
[root@node-3 ~]# docker container inspect 55d28fdc9923
[
...部分輸出省略...
{
"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分配的權重，作用在requests.cpu上
"Memory": 268435456, 內存分配的大小，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資源測試
pod中cpu的限制主要通過requests.cpu和limits.cpu來定義，limits是不能超過的cpu大小，我們通過stress鏡像來驗證，stress是一個cpu和內存的壓側工具，通過指定args參數的定義壓側cpu的大小。監控pod的cpu和內存可通過kubectl top的方式來查看，依賴於監控組件如metric-server或promethus，當前沒有安裝，我們通過docker stats的方式來查看。
1、通過stress鏡像定義一個pod，分配0.25個cores和最大限制0.5個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、應用yaml文件生成pod
[root@node-1 demo]# kubectl apply -f cpu-demo.yaml
pod/cpu-demo created3、查看pod資源分配詳情
[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請求的大小
cpu: 250m4、登陸到特定的node節點，通過docker container stats查看容器的資源使用詳情
在pod所屬的node上通過top查看，cpu的使用率限制百分比爲50%。
通過上面的驗證可以得出結論，我們在stress容器中定義使用1個core，通過limits.cpu限定可使用的cpu大小是500m，測試驗證pod的資源已在容器內部或宿主機上都嚴格限制在50%（node機器上只有一個cpu，如果有2個cpu則會分攤爲25%）。
1.4 memory資源測試
1、通過stress鏡像測試驗證requests.memory和limits.memory的生效範圍，limits.memory定義容器可使用的內存資源大小，當超過內存設定的大小後容器會發生OOM，如下定義一個測試的容器，最大內存不能超過512M,使用stress鏡像--vm-bytes定義壓側內存大小爲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、應用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、查看資源的分配情況
[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: #內存限制大小
memory: 512Mi
Requests: #內存請求大小
memory: 128Mi
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-5qwmc (ro)4、查看容器內存資源的使用情況，分配256M內存，最大可使用爲512Mi，利用率爲50%，此時沒有超過limits限制的大小，容器運行正常
5、當容器內部超過內存的大小會怎麼樣呢，我們將--vm-byte設置爲513M，容器會嘗試運行，超過內存後會OOM，kube-controller-manager會不停的嘗試重啓容器,RESTARTS的次數會不停的增加。
[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"] . #容器中使用內存爲520M
查看容器的狀態爲OOMKilled，RESTARTS的次數不斷的增加，不停的嘗試重啓
[root@node-1 demo]# kubectl get pods memory-stress-demo
NAME READY STATUS RESTARTS AGE
memory-stress-demo 0/1 OOMKilled 3 60s2. Pod服務質量
服務質量QOS（Quality of Service）主要用於pod調度和驅逐時參考的重要因素，不同的QOS其服務質量不同，對應不同的優先級，主要分爲三種類型的Qos：
- BestEffort 盡最大努力分配資源，默認沒有指定resource分配的Qos，優先級最低；
- Burstable 可波動的資源，至少需要分配到requests中的資源，常見的QOS；
- Guaranteed 完全可保障資源，requests和limits定義的資源相同，優先級最高。
2.1 BestEffort最大努力
1、Pod中沒有定義resource，默認的Qos策略爲BestEffort,優先級別最低，當資源比較進展是需要驅逐evice時，優先驅逐BestEffort定義的Pod，如下定義一個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、創建pod並查看Qos策略，qosClass爲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、刪除測試Pod
[root@node-1 demo]# kubectl delete pods nginx-qos-besteffort
pod "nginx-qos-besteffort" deleted2.2 Burstable可波動
1、Pod的服務質量爲Burstable，僅次於Guaranteed的服務質量，至少需要一個container定義了requests，且requests定義的資源小於limits資源
[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: 256Mi2、應用yaml文件生成pod並查看Qos類型
[root@node-1 demo]# kubectl apply -f nginx-qos-burstable.yaml
pod/nginx-qos-burstable created
查看Qos類型
[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 #服務質量是可波動的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-burstable2.3 Guaranteed完全保障
1、resource中定義的cpu和memory必須包含有requests和limits，切requests和limits的值必須相同，其優先級別最高，當出現調度和驅逐時優先保障該類型的Qos,如下定義一個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: 256Mi2、應用yaml文件生成pod並查看pod的Qos類型爲可完全保障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 #服務質量爲可完全保障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寫在最後
本章是kubernetes系列教程第六篇文章，通過介紹resource資源的分配和服務質量Qos，關於resource有節點使用建議：
- requests和limits資源定義推薦不超過1:2，避免分配過多資源而出現資源爭搶，發生OOM；
- pod中默認沒有定義resource，推薦給namespace定義一個limitrange，確保pod能分到資源；
- 防止node上資源過度而出現機器hang住或者OOM，建議node上設置保留和驅逐資源，如保留資源--system-reserved=cpu=200m,memory=1G，驅逐條件--eviction hard=memory.available<500Mi。
附錄
容器計算資源管理：https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/
pod內存資源管理：https://kubernetes.io/docs/tasks/configure-pod-container/assign-memory-resource/
pod cpu資源管理：https://kubernetes.io/docs/tasks/configure-pod-container/assign-cpu-resource/
服務質量QOS：https://kubernetes.io/docs/tasks/configure-pod-container/quality-service-pod/
Docker關於CPU的限制：https://www.cnblogs.com/sparkdev/p/8052522.html
當你的才華撐不起你的野心時，你就應該靜下心來學習