22. DaemonSet のアップデート（RollingUpdate）

このセクションでは、DaemonSet を RollingUpdate でアップデートする方法について紹介します。 DaemonSet では、1 ノードに複数の同一 Pod を作成できないため、Deployment とは異なり一度に超過可能な Pod の数（ maxSurge ）を設定できません。一度に停止可能な Pod の数（ maxUnavailable ）のみを指定してローリングアップデートを行います。

サンプルのマニフェストファイルを新規作成し、以下コードを記述します。

[root@kube-master sample-daemonset]# vi sample-daemonset-rollingupdate.yaml

spec の updateStrategy に type: RollingUpdate を指定します。また、rollingUpdate に maxUnavailable を指定します。ここでは、Pod を一つずつアップデートするために、maxUnavailable を 1 としています。

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: sample-daemonset-rollingupdate
spec:
  updateStrategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
  selector:
    matchLabels:
      app: sample-app
  template:
    metadata:
      labels:
        app: sample-app
    spec:
      containers:
        - name: nginx-container
          image: nginx:1.12

Master サーバーから作成したマニフェストを実行し、Kubernetes クラスタ上にリソースを作成します。

[root@kube-master sample-daemonset]# kubectl apply -f sample-daemonset-rollingupdate.yaml --record
daemonset.apps/sample-daemonset-rollingupdate created
[root@kube-master sample-daemonset]#

Master サーバーから Kubernetes クラスタ上の Pod リソースを確認します。各ノードに Pod が一つずつ起動していることが確認できます。

[root@kube-master sample-daemonset]# kubectl get pods -o wide
NAME                                   READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
sample-daemonset-rollingupdate-hgg4x   1/1     Running   0          4s    10.244.2.81    kube-work2   <none>           <none>
sample-daemonset-rollingupdate-scgmk   1/1     Running   0          4s    10.244.1.151   kube-work1   <none>           <none>
[root@kube-master sample-daemonset]#

Master サーバーから Kubernetes クラスタ上の Pod の詳細情報を確認します。ここでは、各 Pod 上のコンテナで nginx 1.2 のイメージが起動していることが確認できます。

[root@kube-master sample-daemonset]# kubectl describe pods sample-daemonset-rollingupdate
Name:               sample-daemonset-rollingupdate-hgg4x
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kube-work2/192.168.25.102
Start Time:         Sat, 02 Feb 2019 00:48:25 +0900
Labels:             app=sample-app
                    controller-revision-hash=d88f4f445
                    pod-template-generation=1
Annotations:        <none>
Status:             Running
IP:                 10.244.2.81
Controlled By:      DaemonSet/sample-daemonset-rollingupdate
Containers:
  nginx-container:
    Container ID:   docker://d5f03f5aab0f7bafbd12840c895e18acf33a93092a81c7f991ef146f8c2c6e2b
    Image:          nginx:1.12
    Image ID:       docker-pullable://nginx@sha256:72daaf46f11cc753c4eab981cbf869919bd1fee3d2170a2adeac12400f494728
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 02 Feb 2019 00:48:27 +0900
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-75dfq (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-75dfq:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-75dfq
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/disk-pressure:NoSchedule
                 node.kubernetes.io/memory-pressure:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute
                 node.kubernetes.io/unreachable:NoExecute
                 node.kubernetes.io/unschedulable:NoSchedule
Events:
  Type    Reason     Age    From                 Message
  ----    ------     ----   ----                 -------
  Normal  Scheduled  2m24s  default-scheduler    Successfully assigned default/sample-daemonset-rollingupdate-hgg4x to kube-work2
  Normal  Pulled     2m23s  kubelet, kube-work2  Container image "nginx:1.12" already present on machine
  Normal  Created    2m23s  kubelet, kube-work2  Created container
  Normal  Started    2m22s  kubelet, kube-work2  Started container

Name:               sample-daemonset-rollingupdate-scgmk
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kube-work1/192.168.25.101
Start Time:         Sat, 02 Feb 2019 00:48:25 +0900
Labels:             app=sample-app
                    controller-revision-hash=d88f4f445
                    pod-template-generation=1
Annotations:        <none>
Status:             Running
IP:                 10.244.1.151
Controlled By:      DaemonSet/sample-daemonset-rollingupdate
Containers:
  nginx-container:
    Container ID:   docker://471f695699082509c83dfc68842ce785ec1733be05e027b61d24c57709ee7575
    Image:          nginx:1.12
    Image ID:       docker-pullable://nginx@sha256:72daaf46f11cc753c4eab981cbf869919bd1fee3d2170a2adeac12400f494728
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 02 Feb 2019 00:48:26 +0900
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-75dfq (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-75dfq:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-75dfq
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/disk-pressure:NoSchedule
                 node.kubernetes.io/memory-pressure:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute
                 node.kubernetes.io/unreachable:NoExecute
                 node.kubernetes.io/unschedulable:NoSchedule
Events:
  Type    Reason     Age    From                 Message
  ----    ------     ----   ----                 -------
  Normal  Scheduled  2m24s  default-scheduler    Successfully assigned default/sample-daemonset-rollingupdate-scgmk to kube-work1
  Normal  Pulled     2m23s  kubelet, kube-work1  Container image "nginx:1.12" already present on machine
  Normal  Created    2m23s  kubelet, kube-work1  Created container
  Normal  Started    2m23s  kubelet, kube-work1  Started container

[root@kube-master sample-daemonset]#

サンプルのマニフェストファイルを編集し、コンテナイメージを変更します。

[root@kube-master sample-daemonset]# vi sample-daemonset-rollingupdate.yaml

spec の containers イメージを nginx:1.2 から nginx:1.13 に変更します。

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: sample-daemonset-rollingupdate
spec:
  updateStrategy:
    type: RollingUpdate
    rollingUpdate:
      maxUnavailable: 1
  selector:
    matchLabels:
      app: sample-app
  template:
    metadata:
      labels:
        app: sample-app
    spec:
      containers:
        - name: nginx-container
          image: nginx:1.13

Master サーバーから変更したマニフェストを実行し、Kubernetes クラスタ上にリソースを更新してみます。

[root@kube-master sample-daemonset]# kubectl apply -f sample-daemonset-rollingupdate.yaml --record
daemonset.apps/sample-daemonset-rollingupdate configured
[root@kube-master sample-daemonset]#

Master サーバーから Kubernetes クラスタ上の Pod リソースを確認します。ここでは、Pod リソースの名前が変わっていることが確認できます。

[root@kube-master sample-daemonset]# kubectl get pods -o wide
NAME                                   READY   STATUS    RESTARTS   AGE   IP             NODE         NOMINATED NODE   READINESS GATES
sample-daemonset-rollingupdate-6szg4   1/1     Running   0          9s    10.244.2.82    kube-work2   <none>           <none>
sample-daemonset-rollingupdate-g8qvn   1/1     Running   0          12s   10.244.1.152   kube-work1   <none>           <none>
[root@kube-master sample-daemonset]#

Master サーバーから Kubernetes クラスタ上の Pod の詳細情報を確認します。ここでは、各 Pod 上でのコンテナーイメージが nginx 1.3 になっていることが確認できます。

[root@kube-master sample-daemonset]# kubectl describe pods sample-daemonset-rollingupdate
Name:               sample-daemonset-rollingupdate-6szg4
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kube-work2/192.168.25.102
Start Time:         Sat, 02 Feb 2019 00:55:25 +0900
Labels:             app=sample-app
                    controller-revision-hash=679c64dbd8
                    pod-template-generation=2
Annotations:        <none>
Status:             Running
IP:                 10.244.2.82
Controlled By:      DaemonSet/sample-daemonset-rollingupdate
Containers:
  nginx-container:
    Container ID:   docker://2c2aa9d26ffb5ced6280db110fcb6739914341722f7634d6965b981fc97ff72e
    Image:          nginx:1.13
    Image ID:       docker-pullable://nginx@sha256:b1d09e9718890e6ebbbd2bc319ef1611559e30ce1b6f56b2e3b479d9da51dc35
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 02 Feb 2019 00:55:26 +0900
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-75dfq (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-75dfq:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-75dfq
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/disk-pressure:NoSchedule
                 node.kubernetes.io/memory-pressure:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute
                 node.kubernetes.io/unreachable:NoExecute
                 node.kubernetes.io/unschedulable:NoSchedule
Events:
  Type    Reason     Age    From                 Message
  ----    ------     ----   ----                 -------
  Normal  Scheduled  2m30s  default-scheduler    Successfully assigned default/sample-daemonset-rollingupdate-6szg4 to kube-work2
  Normal  Pulled     2m30s  kubelet, kube-work2  Container image "nginx:1.13" already present on machine
  Normal  Created    2m30s  kubelet, kube-work2  Created container
  Normal  Started    2m29s  kubelet, kube-work2  Started container

Name:               sample-daemonset-rollingupdate-g8qvn
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kube-work1/192.168.25.101
Start Time:         Sat, 02 Feb 2019 00:55:22 +0900
Labels:             app=sample-app
                    controller-revision-hash=679c64dbd8
                    pod-template-generation=2
Annotations:        <none>
Status:             Running
IP:                 10.244.1.152
Controlled By:      DaemonSet/sample-daemonset-rollingupdate
Containers:
  nginx-container:
    Container ID:   docker://687b2d1d676bec38ec0f08625e5319add125ac5b8547cb2189aaa6fde8bceb95
    Image:          nginx:1.13
    Image ID:       docker-pullable://nginx@sha256:b1d09e9718890e6ebbbd2bc319ef1611559e30ce1b6f56b2e3b479d9da51dc35
    Port:           <none>
    Host Port:      <none>
    State:          Running
      Started:      Sat, 02 Feb 2019 00:55:23 +0900
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-75dfq (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  default-token-75dfq:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-75dfq
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/disk-pressure:NoSchedule
                 node.kubernetes.io/memory-pressure:NoSchedule
                 node.kubernetes.io/not-ready:NoExecute
                 node.kubernetes.io/unreachable:NoExecute
                 node.kubernetes.io/unschedulable:NoSchedule
Events:
  Type    Reason     Age    From                 Message
  ----    ------     ----   ----                 -------
  Normal  Scheduled  2m33s  default-scheduler    Successfully assigned default/sample-daemonset-rollingupdate-g8qvn to kube-work1
  Normal  Pulled     2m32s  kubelet, kube-work1  Container image "nginx:1.13" already present on machine
  Normal  Created    2m32s  kubelet, kube-work1  Created container
  Normal  Started    2m32s  kubelet, kube-work1  Started container

[root@kube-master sample-daemonset]#

Master サーバーから作成した DaemonSet リソースを削除します。

[root@kube-master sample-daemonset]# kubectl delete daemonset sample-daemonset-rollingupdate
daemonset.extensions "sample-daemonset-rollingupdate" deleted
[root@kube-master sample-daemonset]#

Master サーバーから Kubernetes クラスタ上の Pod リソースを確認します。ここでは、DaemonSet リソースで作成した Pod が削除されていることが確認できます。

[root@kube-master sample-daemonset]# kubectl get pods -o wide
No resources found.
[root@kube-master sample-daemonset]#

22. DaemonSet の アップデート（RollingUpdate）

22. DaemonSet のアップデート（RollingUpdate）