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[kubernetes-실습] Managing State with Deployments

ps.jang on Jan 262021-01-26T05:00:00+09:00
Updated Aug 262021-08-26T00:00:00+09:00 12 min read

ReplicaSet 동작

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# ReplicaSet 생성을 위한 yaml 파일 생성
ps0107@k8smaster1:~$ vi rs.yaml
apiVersion: extensions/v1beta1
kind: ReplicaSet
metadata:
  name: rs-one
spec:
  replicas: 2
  template:
    metadata:
      labels:
        system: ReplicaOne
    spec:
      containers:
      - name: nginx
        image: nginx:1.11.1
        ports:
        - containerPort: 80
 
# ReplicaSet 생성
ps0107@k8smaster1:~$ kubectl create -f rs.yaml 
replicaset.extensions/rs-one created

# 생성된 ReplicaSet 상세 내용 확인
ps0107@k8smaster1:~$ kubectl describe rs rs-one 
Name:         rs-one
Namespace:    default
Selector:     system=ReplicaOne
Labels:       system=ReplicaOne
Annotations:  <none>
Replicas:     2 current / 2 desired
Pods Status:  0 Running / 2 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  system=ReplicaOne
  Containers:
   nginx:
    Image:        nginx:1.11.1
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:       <none>
  Volumes:        <none>
Events:
  Type    Reason            Age   From                   Message
  ----    ------            ----  ----                   -------
  Normal  SuccessfulCreate  10s   replicaset-controller  Created pod: rs-one-dxxl2
  Normal  SuccessfulCreate  10s   replicaset-controller  Created pod: rs-one-k4nm9

# 생성된 pod 확인
ps0107@k8smaster1:~$ kubectl get pods
NAME           READY   STATUS    RESTARTS   AGE
rs-one-dxxl2   1/1     Running   0          24s
rs-one-k4nm9   1/1     Running   0          24s

# ReplicaSet 객체만 삭제하고 하위에 pod는 그냥 놔둠 (--cascade=false)
ps0107@k8smaster1:~$ kubectl delete rs rs-one --cascade=false 
replicaset.extensions "rs-one" deleted

# ReplicaSet 삭제된거 확인
ps0107@k8smaster1:~$ kubectl describe rs rs-one
Error from server (NotFound): replicasets.extensions "rs-one" not found

# pod는 남아 있는지 확인
ps0107@k8smaster1:~$ kubectl get pods
NAME           READY   STATUS    RESTARTS   AGE
rs-one-dxxl2   1/1     Running   0          76s
rs-one-k4nm9   1/1     Running   0          76s

# 다시 ReplicaSet을 생성해 본다.
ps0107@k8smaster1:~$ kubectl create -f rs.yaml 
replicaset.extensions/rs-one created

# 생성이 잘되었다.
ps0107@k8smaster1:~$ kubectl get rs
NAME     DESIRED   CURRENT   READY   AGE
rs-one   2         2         2       6s

# 하지만 pod는 기존에 생성했던 pod 들이다.
ps0107@k8smaster1:~$ kubectl get pod
NAME           READY   STATUS    RESTARTS   AGE
rs-one-dxxl2   1/1     Running   0          107s
rs-one-k4nm9   1/1     Running   0          107s

# pod 하나의 label을 수정해보자 (system: IsolatedPod 로..)
ps0107@k8smaster1:~$ kubectl edit po rs-one-dxxl2
pod/rs-one-dxxl2 edited

# ReplicaSet을 조회해 보면 그대로 2개 러닝중이다.
ps0107@k8smaster1:~$ kubectl get rs
NAME     DESIRED   CURRENT   READY   AGE
rs-one   2         2         2       2m6s

# pod를 system 이라는 label 로 조회해 본다.
# 수정한 거 빼고 새로 하나가 올라온걸 볼수 있다.
# 2개를 유지하려고 하고 있다.
ps0107@k8smaster1:~$ kubectl get pod -L system
NAME           READY   STATUS    RESTARTS   AGE     SYSTEM
rs-one-95sch   1/1     Running   0          23s     ReplicaOne
rs-one-dxxl2   1/1     Running   0          3m56s   IsolatedPod
rs-one-k4nm9   1/1     Running   0          3m56s   ReplicaOne

# ReplicaSet을 삭제 한다
ps0107@k8smaster1:~$ kubectl delete rs rs-one
replicaset.extensions "rs-one" deleted

# system 라벨이 IsolatedPod는 그대로 남아 있다.
ps0107@k8smaster1:~$ kubectl  get pod
NAME           READY   STATUS    RESTARTS   AGE
rs-one-dxxl2   1/1     Running   0          4m26s

# ReplicaSet은 삭제 되어있다.
ps0107@k8smaster1:~$ kubectl get rs
No resources found.

ps0107@k8smaster1:~$ kubectl get po
NAME           READY   STATUS    RESTARTS   AGE
rs-one-dxxl2   1/1     Running   0          4m43s

#  system=IsolatedPod 라벨링 되어 있는 pod를 삭제한다.
ps0107@k8smaster1:~$ kubectl delete po -l system=IsolatedPod
pod "rs-one-dxxl2" deleted

ps0107@k8smaster1:~$ kubectl get pod
No resources found.

DaemonSet 동작

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# DaemonSet 생성을 위한 yaml 파일 생성
ps0107@k8smaster1:~$ cat ds.yaml 
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  name: ds-one
spec:
  template:
    metadata:
      labels:
        system: ReplicaOne
    spec:
      containers:
      - name: nginx
        image: nginx:1.11.1
        ports:
        - containerPort: 80
 
# DaemonSet 생성
ps0107@k8smaster1:~$ kubectl create -f ds.yaml 
daemonset.extensions/ds-one created

# 각 노드에 한개씩 러닝이라 현재 2개 확인 가능
ps0107@k8smaster1:~$ kubectl get ds
NAME     DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
ds-one   2         2         2       2            2           <none>          4s

# 생성된 pod가 각 노드에 한개씩 러닝중이다. 
ps0107@k8smaster1:~$ kubectl get pod -o wide
NAME           READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
ds-one-6sjkv   1/1     Running   0          13s   192.168.0.29   k8smaster1   <none>           <none>
ds-one-hpx96   1/1     Running   0          13s   192.168.1.70   k8sworker1   <none>           <none>

# 현재 러닝중인 nginx의 이미지 버전확인
ps0107@k8smaster1:~$ kubectl describe po ds-one-6sjkv | grep "Image:"
    Image:          nginx:1.11.1

Rolling Updates And Rollback

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# ---------------------------------------------------------------
# updateStrategy의 설정을 OnDelete 로 했을때 테스트
# ---------------------------------------------------------------
# 현재 updateStrategy 설정 확인 
# OnDelete : 이미지를 변경하더라도 이전 버전을 수동 삭제해야 새로운 버전으로 생성됨.
ps0107@k8smaster1:~$ kubectl get ds ds-one -o yaml | grep -A 1 Strategy
updateStrategy:
        type: OnDelete

# daemonSet의 nginx이미지 버전을 수정해보자
ps0107@k8smaster1:~$ kubectl set image ds ds-one nginx=nginx:1.12.1-alpine
daemonset.extensions/ds-one image updated

# pod들의 이미지 버전을 보면 아직 바뀐상태가 아니다.
ps0107@k8smaster1:~$ kubectl describe po ds-one-6sjkv | grep "Image:"
    Image:          nginx:1.11.1    

# 삭제를 해야 바뀐다. 삭제를 해보자.
ps0107@k8smaster1:~$ kubectl delete po ds-one-6sjkv
pod "ds-one-6sjkv" deleted

ps0107@k8smaster1:~$ kubectl get pod -o wide
NAME           READY   STATUS              RESTARTS   AGE    IP             NODE         NOMINATED NODE   READINESS GATES
ds-one-hpx96   1/1     Running             0          9m4s   192.168.1.70   k8sworker1   <none>           <none>
ds-one-rvrdb   0/1     ContainerCreating   0          6s     <none>         k8smaster1   <none>           <none>

ps0107@k8smaster1:~$ kubectl get pod -o wide
NAME           READY   STATUS    RESTARTS   AGE     IP             NODE         NOMINATED NODE   READINESS GATES
ds-one-hpx96   1/1     Running   0          9m19s   192.168.1.70   k8sworker1   <none>           <none>
ds-one-rvrdb   1/1     Running   0          21s     192.168.0.30   k8smaster1   <none>           <none>

# 기존 pod 의 이미지버전
ps0107@k8smaster1:~$ kubectl describe po ds-one-hpx96 | grep "Image:"
    Image:          nginx:1.11.1
 
# 삭제후 새로 생성된 이미지의 버전 이다. (잘 바귄걸로 올라왔다)
ps0107@k8smaster1:~$ kubectl describe po ds-one-rvrdb | grep "Image:"
    Image:          nginx:1.12.1-alpine
 
# edit로 수정후 history를 확인 할 수도 있다.
ps0107@k8smaster1:~$ kubectl rollout history ds ds-one
daemonset.extensions/ds-one 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

# revision 1번은 1.11.1 이전 버전
ps0107@k8smaster1:~$ kubectl rollout history ds ds-one --revision=1
daemonset.extensions/ds-one with revision #1
Pod Template:
  Labels:system=ReplicaOne
  Containers:
   nginx:
    Image:nginx:1.11.1
    Port:80/TCP
    Host Port:0/TCP
    Environment:<none>
    Mounts:<none>
  Volumes:<none>

# revision 2번은 새로 수정한 버전임을 알수 있다.
ps0107@k8smaster1:~$ kubectl rollout history ds ds-one --revision=2
daemonset.extensions/ds-one with revision #2
Pod Template:
  Labels:system=ReplicaOne
  Containers:
   nginx:
    Image:nginx:1.12.1-alpine
    Port:80/TCP
    Host Port:0/TCP
    Environment:<none>
    Mounts:<none>
  Volumes:<none>

# 이전 버전인 1.11.1버전으로 rollout undo를 실행하여 본다.
ps0107@k8smaster1:~$ kubectl rollout undo ds ds-one --to-revision=1
daemonset.extensions/ds-one rolled back

# 그런데 바로 바뀌지 않는다...
ps0107@k8smaster1:~$ kubectl describe po ds-one-rvrdb | grep "Image:"
Image:          nginx:1.12.1-alpine

ps0107@k8smaster1:~$ kubectl describe po ds-one-hpx96 | grep "Image:"
    Image:          nginx:1.11.1  

# 바로 위에서 본 updateStrategy 설정 때문에 pod를 삭제 해야 다시 뜨면서 적용된다.
ps0107@k8smaster1:~$ kubectl delete po ds-one-rvrdb
pod "ds-one-rvrdb" deleted

# 삭제 후 새로 생성된 pod를 확인할 수 있다
ps0107@k8smaster1:~$ kubectl get po
NAME           READY   STATUS    RESTARTS   AGE
ds-one-65r2h   1/1     Running   0          4s
ds-one-hpx96   1/1     Running   0          12m

# 새로 생성된 pod의 이미지 버전을 확인해본다. 정상적으로 undo 되어 올라왔다.
ps0107@k8smaster1:~$ kubectl describe po ds-one-65r2h | grep "Image:"
    Image:          nginx:1.11.1

# 현재 ds-one 객체의 상세 정보를 확인해본다.
ps0107@k8smaster1:~$ kubectl get ds ds-one -o yaml
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  creationTimestamp: "2020-02-03T03:08:40Z"
  generation: 3
  labels:
    system: ReplicaOne
  name: ds-one
  namespace: default
  resourceVersion: "670771"
  selfLink: /apis/extensions/v1beta1/namespaces/default/daemonsets/ds-one
  uid: cd8e3a1e-8c9a-4a74-96ea-b0030e5711ae
spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      system: ReplicaOne
  template:
    metadata:
      creationTimestamp: null
      labels:
        system: ReplicaOne
    spec:
      containers:
      - image: nginx:1.11.1
        imagePullPolicy: IfNotPresent
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
  templateGeneration: 3
  updateStrategy:
    type: OnDelete
status:
  currentNumberScheduled: 2
  desiredNumberScheduled: 2
  numberAvailable: 2
  numberMisscheduled: 0
  numberReady: 2
  observedGeneration: 3
  updatedNumberScheduled: 2

# ---------------------------------------------------------------
# updateStrategy의 설정을 RollingUpdate 로 수정후 테스트 해보자
# ---------------------------------------------------------------
# 기존 객체에서 복사해서 name과 updateStrategy 부분을 수정해 보자
ps0107@k8smaster1:~$ kubectl get ds ds-one -o yaml --export > ds2.yaml 
Flag --export has been deprecated, This flag is deprecated and will be removed in future.

ps0107@k8smaster1:~$ vi ds2.yaml 
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
  creationTimestamp: null
  generation: 1
  labels:
    system: ReplicaOne
  name: ds-two
  selfLink: /apis/extensions/v1beta1/namespaces/default/daemonsets/ds-one
spec:
  revisionHistoryLimit: 10
  selector:
    matchLabels:
      system: ReplicaOne
  template:
    metadata:
      creationTimestamp: null
      labels:
        system: ReplicaOne
    spec:
      containers:
      - image: nginx:1.11.1
        imagePullPolicy: IfNotPresent
        name: nginx
        ports:
        - containerPort: 80
          protocol: TCP
        resources: {}
        terminationMessagePath: /dev/termination-log
        terminationMessagePolicy: File
      dnsPolicy: ClusterFirst
      restartPolicy: Always
      schedulerName: default-scheduler
      securityContext: {}
      terminationGracePeriodSeconds: 30
  templateGeneration: 3
  updateStrategy:
    type: RollingUpdate
status:
  currentNumberScheduled: 0
  desiredNumberScheduled: 0
  numberMisscheduled: 0
  numberReady: 0

# 새로운 ds-two객체를 생성해 보자.
ps0107@k8smaster1:~$ kubectl create -f ds2.yaml 
daemonset.extensions/ds-two created

# 새로 pod가 2개 생성되었다.
ps0107@k8smaster1:~$ kubectl get po
NAME           READY   STATUS    RESTARTS   AGE
ds-one-65r2h   1/1     Running   0          4m30s
ds-one-hpx96   1/1     Running   0          16m
ds-two-49d8t   1/1     Running   0          6s
ds-two-sgpdh   1/1     Running   0          6s

# 생성된 pod의 이미지 버전을 확인해보자 (1.11.1 이다)
ps0107@k8smaster1:~$ kubectl describe po ds-two-49d8t | grep "Image:" 
Image:          nginx:1.11.1 

# edit 명령으로 이미지 버전을 수정해 보자 (1.12.1-alpine으로)
ps0107@k8smaster1:~$ kubectl edit ds ds-two 
daemonset.extensions/ds-two edited

# ds-two의 상태 확인
ps0107@k8smaster1:~$ kubectl get ds ds-two
NAME     DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE
ds-two   2         2         1       1            1           <none>          82s

# 생성된 pod를 확인해 본다.
ps0107@k8smaster1:~$ kubectl get pod
NAME           READY   STATUS    RESTARTS   AGE
ds-one-65r2h   1/1     Running   0          6m8s
ds-one-hpx96   1/1     Running   0          18m
ds-two-2px2q   1/1     Running   0          19s
ds-two-kpsfx   1/1     Running   0          35s

# 두개의 pod 가 버전이 수정된걸로 다시 생성되었다.
ps0107@k8smaster1:~$ kubectl describe po ds-two-2px2q | grep "Image:"   
Image:          nginx:1.12.1-alpine

ps0107@k8smaster1:~$ kubectl describe po ds-two-kpsfx | grep "Image:"
Image:          nginx:1.12.1-alpine

# rollout 된 상태 확인
ps0107@k8smaster1:~$ kubectl rollout status ds ds-two 
daemon set "ds-two" successfully rolled out

ps0107@k8smaster1:~$ kubectl rollout history ds ds-two
daemonset.extensions/ds-two 
REVISION  CHANGE-CAUSE
1         <none>
2         <none>

ps0107@k8smaster1:~$ kubectl rollout history ds ds-two --revision=2
daemonset.extensions/ds-two with revision #2
Pod Template:
  Labels:system=ReplicaOne
  Containers:
   nginx:
    Image:nginx:1.12.1-alpine
    Port:80/TCP
    Host Port:0/TCP
    Environment:<none>
    Mounts:<none>
  Volumes:<none>

# 테스트한 객체 삭제
ps0107@k8smaster1:~$ kubectl delete ds ds-two 
daemonset.extensions "ds-two" deleted
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