[쿠버네티스] 치트 메모장

       Welcome to the KodeKloud Hands-On lab                                                                
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controlplane ~ ➜  k get pods
No resources found in default namespace.

controlplane ~ ➜  k get replicaset
No resources found in default namespace.

controlplane ~ ➜  k get deploy
No resources found in default namespace.

controlplane ~ ➜  k get deployment
No resources found in default namespace.

controlplane ~ ➜  k get deploy
NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
frontend-deployment   0/4     4            0           7s

controlplane ~ ➜  k get replicaset
NAME                            DESIRED   CURRENT   READY   AGE
frontend-deployment-649fb4c7c   4         4         0       24s

controlplane ~ ➜  k get pods
NAME                                  READY   STATUS             RESTARTS   AGE
frontend-deployment-649fb4c7c-fp7nh   0/1     ErrImagePull       0          37s
frontend-deployment-649fb4c7c-k77p9   0/1     ImagePullBackOff   0          37s
frontend-deployment-649fb4c7c-mjmnf   0/1     ErrImagePull       0          37s
frontend-deployment-649fb4c7c-tqr8w   0/1     ErrImagePull       0          37s

controlplane ~ ➜  k get pods
NAME                                  READY   STATUS             RESTARTS   AGE
frontend-deployment-649fb4c7c-fp7nh   0/1     ImagePullBackOff   0          118s
frontend-deployment-649fb4c7c-k77p9   0/1     ErrImagePull       0          118s
frontend-deployment-649fb4c7c-mjmnf   0/1     ErrImagePull       0          118s
frontend-deployment-649fb4c7c-tqr8w   0/1     ImagePullBackOff   0          118s

controlplane ~ ➜  k get deploy
NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
frontend-deployment   0/4     4            0           2m21s

controlplane ~ ➜  k describe deploy frontend-deployment
Name:                   frontend-deployment
Namespace:              default
CreationTimestamp:      Tue, 21 Jan 2025 08:01:30 +0000
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               name=busybox-pod
Replicas:               4 desired | 4 updated | 4 total | 0 available | 4 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  name=busybox-pod
  Containers:
   busybox-container:
    Image:      busybox888
    Port:       <none>
    Host Port:  <none>
    Command:
      sh
      -c
      echo Hello Kubernetes! && sleep 3600
    Environment:   <none>
    Mounts:        <none>
  Volumes:         <none>
  Node-Selectors:  <none>
  Tolerations:     <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  <none>
NewReplicaSet:   frontend-deployment-649fb4c7c (4/4 replicas created)
Events:
  Type    Reason             Age   From                   Message
  ----    ------             ----  ----                   -------
  Normal  ScalingReplicaSet  3m9s  deployment-controller  Scaled up replica set frontend-deployment-649fb4c7c to 4

controlplane ~ ➜  k describe deploy frontend-deployment
Name:                   frontend-deployment
Namespace:              default
CreationTimestamp:      Tue, 21 Jan 2025 08:01:30 +0000
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               name=busybox-pod
Replicas:               4 desired | 4 updated | 4 total | 0 available | 4 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  name=busybox-pod
  Containers:
   busybox-container:
    Image:      busybox888
    Port:       <none>
    Host Port:  <none>
    Command:
      sh
      -c
      echo Hello Kubernetes! && sleep 3600
    Environment:   <none>
    Mounts:        <none>
  Volumes:         <none>
  Node-Selectors:  <none>
  Tolerations:     <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  <none>
NewReplicaSet:   frontend-deployment-649fb4c7c (4/4 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  3m55s  deployment-controller  Scaled up replica set frontend-deployment-649fb4c7c to 4

controlplane ~ ➜  k get pods -l busybox-pod
No resources found in default namespace.

controlplane ~ ➜  k get pods
NAME                                  READY   STATUS             RESTARTS   AGE
frontend-deployment-649fb4c7c-fp7nh   0/1     ImagePullBackOff   0          5m15s
frontend-deployment-649fb4c7c-k77p9   0/1     ImagePullBackOff   0          5m15s
frontend-deployment-649fb4c7c-mjmnf   0/1     ImagePullBackOff   0          5m15s
frontend-deployment-649fb4c7c-tqr8w   0/1     ImagePullBackOff   0          5m15s

controlplane ~ ➜  k describe pod frontend-deployment-649fb4c7c-fp7nh
Name:             frontend-deployment-649fb4c7c-fp7nh
Namespace:        default
Priority:         0
Service Account:  default
Node:             controlplane/192.168.187.116
Start Time:       Tue, 21 Jan 2025 08:01:30 +0000
Labels:           name=busybox-pod
                  pod-template-hash=649fb4c7c
Annotations:      <none>
Status:           Pending
IP:               10.42.0.12
IPs:
  IP:           10.42.0.12
Controlled By:  ReplicaSet/frontend-deployment-649fb4c7c
Containers:
  busybox-container:
    Container ID:  
    Image:         busybox888
    Image ID:      
    Port:          <none>
    Host Port:     <none>
    Command:
      sh
      -c
      echo Hello Kubernetes! && sleep 3600
    State:          Waiting
      Reason:       ImagePullBackOff
    Ready:          False
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-hl5dr (ro)
Conditions:
  Type                        Status
  PodReadyToStartContainers   True 
  Initialized                 True 
  Ready                       False 
  ContainersReady             False 
  PodScheduled                True 
Volumes:
  kube-api-access-hl5dr:
    Type:                    Projected (a volume that contains injected data from multiple sources)
    TokenExpirationSeconds:  3607
    ConfigMapName:           kube-root-ca.crt
    ConfigMapOptional:       <nil>
    DownwardAPI:             true
QoS Class:                   BestEffort
Node-Selectors:              <none>
Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
  Type     Reason     Age                    From               Message
  ----     ------     ----                   ----               -------
  Normal   Scheduled  5m57s                  default-scheduler  Successfully assigned default/frontend-deployment-649fb4c7c-fp7nh to controlplane
  Normal   Pulling    4m28s (x4 over 5m56s)  kubelet            Pulling image "busybox888"
  Warning  Failed     4m28s (x4 over 5m56s)  kubelet            Failed to pull image "busybox888": failed to pull and unpack image "docker.io/library/busybox888:latest": failed to resolve reference "docker.io/library/busybox888:latest": pull access denied, repository does not exist or may require authorization: server message: insufficient_scope: authorization failed
  Warning  Failed     4m28s (x4 over 5m56s)  kubelet            Error: ErrImagePull
  Warning  Failed     4m2s (x6 over 5m55s)   kubelet            Error: ImagePullBackOff
  Normal   BackOff    49s (x20 over 5m55s)   kubelet            Back-off pulling image "busybox888"

controlplane ~ ➜  ls
deployment-definition-1.yaml  sample.yaml

controlplane ~ ➜  k get deploy 
NAME                  READY   UP-TO-DATE   AVAILABLE   AGE
frontend-deployment   0/4     4            0           7m32s

controlplane ~ ➜  k describe frontend-deployment
error: the server doesn't have a resource type "frontend-deployment"

controlplane ~ ✖ k describe deploy frontend-deployment
Name:                   frontend-deployment
Namespace:              default
CreationTimestamp:      Tue, 21 Jan 2025 08:01:30 +0000
Labels:                 <none>
Annotations:            deployment.kubernetes.io/revision: 1
Selector:               name=busybox-pod
Replicas:               4 desired | 4 updated | 4 total | 0 available | 4 unavailable
StrategyType:           RollingUpdate
MinReadySeconds:        0
RollingUpdateStrategy:  25% max unavailable, 25% max surge
Pod Template:
  Labels:  name=busybox-pod
  Containers:
   busybox-container:
    Image:      busybox888
    Port:       <none>
    Host Port:  <none>
    Command:
      sh
      -c
      echo Hello Kubernetes! && sleep 3600
    Environment:   <none>
    Mounts:        <none>
  Volumes:         <none>
  Node-Selectors:  <none>
  Tolerations:     <none>
Conditions:
  Type           Status  Reason
  ----           ------  ------
  Available      False   MinimumReplicasUnavailable
  Progressing    True    ReplicaSetUpdated
OldReplicaSets:  <none>
NewReplicaSet:   frontend-deployment-649fb4c7c (4/4 replicas created)
Events:
  Type    Reason             Age    From                   Message
  ----    ------             ----   ----                   -------
  Normal  ScalingReplicaSet  7m47s  deployment-controller  Scaled up replica set frontend-deployment-649fb4c7c to 4

controlplane ~ ➜  vi deployment-definition-1.yaml

controlplane ~ ➜  k apply -f deployment-definition-1.yaml
Error from server (BadRequest): error when creating "deployment-definition-1.yaml": deployment in version "v1" cannot be handled as a Deployment: no kind "deployment" is registered for version "apps/v1" in scheme "k8s.io/apimachinery@v1.31.0-k3s3/pkg/runtime/scheme.go:100"

controlplane ~ ✖ vi deployment-definition-1.yaml

controlplane ~ ➜  k apply -f deployment-definition-1.yaml
deployment.apps/deployment-1 created

controlplane ~ ➜  vi deploy.yaml

controlplane ~ ➜  k apply -f deploy.yaml
deployment.apps/httpd-frontend created

controlplane ~ ➜

 

Practice Test - Node Affinity

 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: blue
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      affinity:
        nodeAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            nodeSelectorTerms:
            - matchExpressions:
              - key: color
                operator: In
                values:
                - blue
      containers:
      - name: nginx
        image: nginx
        ports:
        - containerPort: 80
      tolerations:
      - key: "color"
        operator: "Equal"
        value: "blue"
        effect: "NoSchedule"

 

Practice Test - Resource Limits

apiVersion: v1
kind: Pod
metadata:
  name: elephant
  namespace: default
spec:
  containers:
  - name: memory-demo-ctr
    image: polinux/stress
    resources:
      requests:
        memory: "20Mi"
      limits:
        memory: "20Mi"
    command: ["stress"]
    args: ["--vm", "1", "--vm-bytes", "150M", "--vm-hang", "1"]

 

Practice Test - Static PODs

First, let's identify the node in which the pod called static-greenbox is created. To do this, run:
root@controlplane:~# kubectl get pods --all-namespaces -o wide  | grep static-greenbox
default       static-greenbox-node01                 1/1     Running   0          19s     10.244.1.2   node01       <none>           <none>
root@controlplane:~#
From the result of this command, we can see that the pod is running on node01.


Next, SSH to node01 and identify the path configured for static pods in this node.

Important: The path need not be /etc/kubernetes/manifests. Make sure to check the path configured in the kubelet configuration file.
root@controlplane:~# ssh node01 
root@node01:~# ps -ef |  grep /usr/bin/kubelet 
root        4147       1  0 14:05 ?        00:00:00 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --container-runtime-endpoint=unix:///var/run/containerd/containerd.sock --pod-infra-container-image=registry.k8s.io/pause:3.9
root        4773    4733  0 14:05 pts/0    00:00:00 grep /usr/bin/kubelet

root@node01:~# grep -i staticpod /var/lib/kubelet/config.yaml
staticPodPath: /etc/just-to-mess-with-you

root@node01:~# 
Here the staticPodPath is /etc/just-to-mess-with-you


Navigate to this directory and delete the YAML file:
root@node01:/etc/just-to-mess-with-you# ls
greenbox.yaml
root@node01:/etc/just-to-mess-with-you# rm -rf greenbox.yaml 
root@node01:/etc/just-to-mess-with-you#
Exit out of node01 using CTRL + D or type exit. You should return to the controlplane node. Check if the static-greenbox pod has been deleted:
root@controlplane:~# kubectl get pods --all-namespaces -o wide  | grep static-greenbox
root@controlplane:~#

 

 Multiple Schedulers

Kubernetes의 기본 스케줄러 이미지는 Kubernetes 버전에 따라 결정됩니다. 디폴트 스케줄러의 이미지를 확인하려면 다음 단계를 따를 수 있습니다.

1. 기본 스케줄러 파드 확인
기본 스케줄러의 이미지를 확인하려면, kube-scheduler 파드를 살펴보아야 합니다. 기본적으로 kube-system 네임스페이스에 배치되어 있습니다.

bash
복사
편집
kubectl get pods -n kube-system | grep kube-scheduler
출력 예:

sql
복사
편집
kube-scheduler-controlplane   1/1     Running   0          10m
2. 기본 스케줄러 이미지 확인
기본 스케줄러의 이미지를 확인하려면 다음 명령어를 실행합니다.

bash
복사
편집
kubectl describe pod kube-scheduler-controlplane -n kube-system | grep Image
출력 예:

bash
복사
편집
Image: k8s.gcr.io/kube-scheduler:v1.25.0
여기서, **이미지 이름은 k8s.gcr.io/kube-scheduler:<version>**입니다.