Ubuntu で Kubernetes 三昧その７(Deamonset)

[Ubuntu で Kubernetes 三昧その６(clusterrole, serviceaccount, Deployment)](https://qiita.com/intrajp/items/cc9221ec1e4536b7903c)の続きです。

このコマンドを実行します。
コントロールプレーンです。
```
@controlplane1:~/kubernetes-examples$ kubectl apply -f daemonset/nginx.yaml
daemonset.apps/nginx-deployment created
```
ここで、ちょっとしたことに気づきました。どうやら、コントロールプレーンがうまく動いていないようです。
```
@masternode1:~$ kubectl describe node masternode1
Name:               masternode1
Roles:              control-plane
Labels:             beta.kubernetes.io/arch=amd64
                    beta.kubernetes.io/os=linux
                    kubernetes.io/arch=amd64
                    kubernetes.io/hostname=masternode1
                    kubernetes.io/os=linux
                    node-role.kubernetes.io/control-plane=
                    node.kubernetes.io/exclude-from-external-load-balancers=
Annotations:        kubeadm.alpha.kubernetes.io/cri-socket: unix:///var/run/containerd/containerd.sock
                    node.alpha.kubernetes.io/ttl: 0
                    volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp:  Sat, 21 Jun 2025 18:27:56 +0900
Taints:             node.kubernetes.io/unreachable:NoExecute
                    node-role.kubernetes.io/control-plane:NoSchedule
                    node.kubernetes.io/unreachable:NoSchedule
Unschedulable:      false
Lease:
  HolderIdentity:  masternode1
  AcquireTime:     <unset>
  RenewTime:       Mon, 23 Jun 2025 09:04:56 +0900
Conditions:
  Type                 Status    LastHeartbeatTime                 LastTransitionTime                Reason              Message
  ----                 ------    -----------------                 ------------------                ------              -------
  NetworkUnavailable   False     Sun, 22 Jun 2025 10:55:10 +0900   Sun, 22 Jun 2025 10:55:10 +0900   WeaveIsUp           Weave pod has set this
  MemoryPressure       Unknown   Mon, 23 Jun 2025 09:04:23 +0900   Mon, 23 Jun 2025 09:08:32 +0900   NodeStatusUnknown   Kubelet stopped posting node status.
  DiskPressure         Unknown   Mon, 23 Jun 2025 09:04:23 +0900   Mon, 23 Jun 2025 09:08:32 +0900   NodeStatusUnknown   Kubelet stopped posting node status.
  PIDPressure          Unknown   Mon, 23 Jun 2025 09:04:23 +0900   Mon, 23 Jun 2025 09:08:32 +0900   NodeStatusUnknown   Kubelet stopped posting node status.
  Ready                Unknown   Mon, 23 Jun 2025 09:04:23 +0900   Mon, 23 Jun 2025 09:08:32 +0900   NodeStatusUnknown   Kubelet stopped posting node status.
Addresses:
  InternalIP:  10.0.2.15
  Hostname:    masternode1
Capacity:
  cpu:                4
  ephemeral-storage:  25623780Ki
  hugepages-2Mi:      0
  memory:             4008868Ki
  pods:               110
Allocatable:
  cpu:                4
  ephemeral-storage:  23614875609
  hugepages-2Mi:      0
  memory:             3906468Ki
  pods:               110
System Info:
  Machine ID:                 43cd959a38a540419cbe1905a9d4bea1
  System UUID:                30f05dee-44f6-0a4d-ae10-65bf368cb4c2
  Boot ID:                    66a21590-cc21-4214-94b7-0e5e01adf03d
  Kernel Version:             6.11.0-26-generic
  OS Image:                   Ubuntu 24.04.2 LTS
  Operating System:           linux
  Architecture:               amd64
  Container Runtime Version:  containerd://2.1.3
  Kubelet Version:            v1.33.2
  Kube-Proxy Version:         
Non-terminated Pods:          (6 in total)
  Namespace                   Name                                   CPU Requests  CPU Limits  Memory Requests  Memory Limits  Age
  ---------                   ----                                   ------------  ----------  ---------------  -------------  ---
  kube-system                 etcd-masternode1                       100m (2%)     0 (0%)      100Mi (2%)       0 (0%)         2d
  kube-system                 kube-apiserver-masternode1             250m (6%)     0 (0%)      0 (0%)           0 (0%)         2d
  kube-system                 kube-controller-manager-masternode1    200m (5%)     0 (0%)      0 (0%)           0 (0%)         2d
  kube-system                 kube-proxy-km2s7                       0 (0%)        0 (0%)      0 (0%)           0 (0%)         2d
  kube-system                 kube-scheduler-masternode1             100m (2%)     0 (0%)      0 (0%)           0 (0%)         2d
  kube-system                 weave-net-v2fhz                        100m (2%)     0 (0%)      0 (0%)           0 (0%)         31h
Allocated resources:
  (Total limits may be over 100 percent, i.e., overcommitted.)
  Resource           Requests    Limits
  --------           --------    ------
  cpu                750m (18%)  0 (0%)
  memory             100Mi (2%)  0 (0%)
  ephemeral-storage  0 (0%)      0 (0%)
  hugepages-2Mi      0 (0%)      0 (0%)
Events:
  Type    Reason          Age   From             Message
  ----    ------          ----  ----             -------
  Normal  RegisteredNode  11m   node-controller  Node masternode1 event: Registered Node masternode1 in Controller
```
kubelet は立ち上がっているものの、ホスト名を controlplane1 に変更したのが原因で、不具合が発生しているようでした。

名前を、masternode1 に戻し、kubelete をリスタートしました。
事象は解消しました。
それでは、Daemonsetを確認します。名前が deployment となっていて紛らわしいですが。
```
@masternode1:~$ kubectl get daemonsets -o wide
NAME               DESIRED   CURRENT   READY   UP-TO-DATE   AVAILABLE   NODE SELECTOR   AGE   CONTAINERS        IMAGES         SELECTOR
nginx-deployment   1         1         1       1            1           <none>          34m   nginxdeployment   nginx:latest   app=nginxdeployment

@masternode1:~$ kubectl get pods -o wide
NAME                     READY   STATUS    RESTARTS      AGE   IP          NODE          NOMINATED NODE   READINESS GATES
nginx-deployment-t2xbx   1/1     Running   1 (32m ago)   38m   10.32.0.4   workernode1   <none>           <none>

@masternode1:~$ kubectl describe pod nginx-deployment-t2xbx
Name:             nginx-deployment-t2xbx
Namespace:        default
Priority:         0
Service Account:  default
Node:             workernode1/10.0.2.7
...(snip)...
```
DaemonSet は workernode1 にだけ作成されていて、コントロールプレーンノードに作成されないのは、ノードを保護するための Taint が原因であり、正常な動作です。

つづく。

参考：

https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/