LABS – CERTIFIED KUBERNETES ADMINISTRATOR WITH PRACTICE TESTS > SCHEDULING – NODE AFFINITY
Scheduling
01. How many Labels exist on node node01?
ask : 5
# 클러스터의 노드를 레이블과 함께 나열하자.
kubectl get nodes --show-labels
root@controlplane:~# kubectl describe node node01 | grep -i label
Labels: beta.kubernetes.io/arch=amd64
root@controlplane:~# kubectl describe node node01
Name: node01
Roles: <none>
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=node01
kubernetes.io/os=linux
Annotations: flannel.alpha.coreos.com/backend-data: {"VNI":1,"VtepMAC":"d6:38:97:18:d9:80"}
flannel.alpha.coreos.com/backend-type: vxlan
flannel.alpha.coreos.com/kube-subnet-manager: true
flannel.alpha.coreos.com/public-ip: 10.9.6.3
kubeadm.alpha.kubernetes.io/cri-socket: /var/run/dockershim.sock
node.alpha.kubernetes.io/ttl: 0
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Wed, 19 Jan 2022 05:27:27 +0000
Taints: <none>
Unschedulable: false
Lease:
HolderIdentity: node01
AcquireTime: <unset>
RenewTime: Wed, 19 Jan 2022 05:39:28 +0000
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Wed, 19 Jan 2022 05:27:34 +0000 Wed, 19 Jan 2022 05:27:34 +0000 FlannelIsUp Flannel is running on this node
MemoryPressure False Wed, 19 Jan 2022 05:37:42 +0000 Wed, 19 Jan 2022 05:27:27 +0000 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Wed, 19 Jan 2022 05:37:42 +0000 Wed, 19 Jan 2022 05:27:27 +0000 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Wed, 19 Jan 2022 05:37:42 +0000 Wed, 19 Jan 2022 05:27:27 +0000 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Wed, 19 Jan 2022 05:37:42 +0000 Wed, 19 Jan 2022 05:27:38 +0000 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 10.9.6.3
Hostname: node01
Capacity:
cpu: 36
ephemeral-storage: 507944172Ki
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 214588000Ki
pods: 110
Allocatable:
cpu: 36
ephemeral-storage: 468121348141
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 214485600Ki
pods: 110
System Info:
Machine ID: e8574b7bc3784a8dbca351f47f17972f
System UUID: df4f7349-5604-cb04-432c-f7c9a46f5ce0
Boot ID: 06683fbc-cc7d-4b3c-873c-79494ee99344
Kernel Version: 5.4.0-1060-gcp
OS Image: Ubuntu 18.04.5 LTS
Operating System: linux
Architecture: amd64
Container Runtime Version: docker://19.3.0
Kubelet Version: v1.20.0
Kube-Proxy Version: v1.20.0
PodCIDR: 10.244.1.0/24
PodCIDRs: 10.244.1.0/24
Non-terminated Pods: (2 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits AGE
--------- ---- ------------ ---------- --------------- ------------- ---
kube-system kube-flannel-ds-ft4fz 100m (0%) 100m (0%) 50Mi (0%) 300Mi (0%) 12m
kube-system kube-proxy-h6v5f 0 (0%) 0 (0%) 0 (0%) 0 (0%) 12m
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 100m (0%) 100m (0%)
memory 50Mi (0%) 300Mi (0%)
ephemeral-storage 0 (0%) 0 (0%)
hugepages-1Gi 0 (0%) 0 (0%)
hugepages-2Mi 0 (0%) 0 (0%)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 12m kubelet Starting kubelet.
Normal NodeHasSufficientMemory 12m kubelet Node node01 status is now: NodeHasSufficientMemory
Normal NodeHasNoDiskPressure 12m kubelet Node node01 status is now: NodeHasNoDiskPressure
Normal NodeHasSufficientPID 12m kubelet Node node01 status is now: NodeHasSufficientPID
Normal NodeAllocatableEnforced 12m kubelet Updated Node Allocatable limit across pods
Normal Starting 11m kube-proxy Starting kube-proxy.
Normal NodeReady 11m kubelet Node node01 status is now: NodeReady02. What is the value set to the label beta.kubernetes.io/arch on node01?
ask : amd64
-- beta.kubernetes.io/arch=amd64
03. Apply a label color=blue to node node01
- color = blue
# 노드 한 개를 선택하고, 레이블을 추가하자.
kubectl label nodes node01 color=blue
# kubectl label nodes <your-node-name> color=blue
# <your-node-name> 는 선택한 노드의 이름이다.
# 선택한 노드가 color=blue 레이블을 갖고 있는지 확인하자.
# kubectl get nodes --show-labels04. Create a new deployment named blue with the nginx image and 3 replicas.
- Name: blue
- Replicas: 3
- Image: nginx
kubectl create deployment blue --image=nginx --replicas=305. Which nodes can the pods for the blue deployment be placed on?
Make sure to check taints on both nodes!
ask : controlplane & node01
Check if controlplane and node01 have any taints
on them that will prevent the pods to be scheduled on them.
If there are no taints, the pods can be scheduled on either node.
So run the following command to check the taints on both nodes.
kubectl describe node controlplane | grep -i taints
kubectl describe node node01 | grep -i taints
root@controlplane:~# kubectl describe node controlplane | grep -i taints
Taints: <none>
root@controlplane:~# kubectl describe node node01 | grep -i taints
Taints: <none>06. Set Node Affinity to the deployment to place the pods on node01 only.
- Name: blue
- Replicas: 3
- Image: nginx
- NodeAffinity: requiredDuringSchedulingIgnoredDuringExecution
- Key: color
- values: blue
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: blue
spec:
replicas: 3
selector:
matchLabels:
run: nginx
template:
metadata:
labels:
run: nginx
spec:
containers:
- image: nginx
imagePullPolicy: Always
name: nginx
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: color
operator: In
values:
- blueapply 로 명령어 칠경우 아래와 같은 에러가 나므로 kubectl create -f sample.yaml 로 !
root@controlplane:~# kubectl apply -f sample.yaml
Warning: resource deployments/blue is missing the kubectl.kubernetes.io/last-applied-configuration annotation which is required by kubectl apply. kubectl apply should only be used on resources created declaratively by either kubectl create --save-config or kubectl apply. The missing annotation will be patched automatically.
The Deployment "blue" is invalid: spec.selector: Invalid value: v1.LabelSelector{MatchLabels:map[string]string{"app":"blue", "run":"nginx"}, MatchExpressions:[]v1.LabelSelectorRequirement(nil)}: field is immutable07. Which nodes are the pods placed on now?
ask : node01
root@controlplane:~# kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
blue-77978c84c6-bfgtk 1/1 Running 0 3m41s 10.244.1.8 node01 <none> <none>
blue-77978c84c6-j2ss8 1/1 Running 0 3m41s 10.244.1.7 node01 <none> <none>
blue-77978c84c6-pc7km 1/1 Running 0 3m41s 10.244.1.6 node01 <none> <none>
08. Create a new deployment named red with the nginx image and 2 replicas,
and ensure it gets placed on the controlplane node only.
Use the label - node-role.kubernetes.io/master - set on the controlplane node.
- Name: red
- Replicas: 2
- Image: nginx
- NodeAffinity: requiredDuringSchedulingIgnoredDuringExecution
- Key: node-role.kubernetes.io/master
- Use the right operator
---
# 오답...
apiVersion: apps/v1
kind: Deployment
metadata:
name: red
spec:
replicas: 2
selector:
matchLabels:
run: nginx
template:
metadata:
labels:
run: nginx
spec:
containers:
- image: nginx
imagePullPolicy: Always
name: nginx
nodeName: controlplane
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: label
operator: In
values:
- node-role.kubernetes.io/master# 정답...
apiVersion: apps/v1
kind: Deployment
metadata:
name: red
spec:
replicas: 2
selector:
matchLabels:
run: nginx
template:
metadata:
labels:
run: nginx
spec:
containers:
- image: nginx
imagePullPolicy: Always
name: nginx
affinity:
nodeAffinity:
requiredDuringSchedulingIgnoredDuringExecution:
nodeSelectorTerms:
- matchExpressions:
- key: node-role.kubernetes.io/master
operator: Exists# tip
# -- dry-run=client 옵션을 적용하면 실제 Kubernetes 에 resource 가 생성되지않고,
# nginx-pod.yaml 파일을 생성해줌
kubectl run red --image=nginx --dry-run=client -o yaml > nginx-pod.yaml# Bookmark
https://kubernetes.io/ko/docs/tasks/configure-pod-container/assign-pods-nodes-using-node-affinity/
노드 어피니티를 사용해 노드에 파드 할당
이 문서는 쿠버네티스 클러스터의 특정 노드에 노드 어피니티를 사용해 쿠버네티스 파드를 할당하는 방법을 설명한다. 시작하기 전에 쿠버네티스 클러스터가 필요하고, kubectl 커맨드-라인 툴이
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