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目錄

• 一.系統(tǒng)環(huán)境
• 二.前言
• 三.靜態(tài)pod
• 3.1 何為靜態(tài)pod
• 3.2 創(chuàng)建靜態(tài)pod
• 3.2.1 使用–pod-manifest-path指定靜態(tài)pod目錄
• 3.2.2 靜態(tài)pod默認(rèn)目錄/etc/kubernetes/manifests

一.系統(tǒng)環(huán)境

Kubernetes集群架構(gòu)：k8scloude1作為master節(jié)點(diǎn)，k8scloude2，k8scloude3作為worker節(jié)點(diǎn)

二.前言

本文介紹靜態(tài) Pod，靜態(tài) Pod 在指定的節(jié)點(diǎn)上由 kubelet 守護(hù)進(jìn)程直接管理，不需要 API 服務(wù)器監(jiān)管。

創(chuàng)建靜態(tài)pod的前提是已經(jīng)有一套可以正常運(yùn)行的Kubernetes集群，關(guān)于Kubernetes(k8s)集群的安裝部署，可以查看博客《Centos7 安裝部署Kubernetes(k8s)集群》https://www.jb51.net/article/266741.htm

三.靜態(tài)pod

3.1 何為靜態(tài)pod

靜態(tài) Pod 在指定的節(jié)點(diǎn)上由 kubelet 守護(hù)進(jìn)程直接管理，不需要 API 服務(wù)器監(jiān)管。 與由控制面管理的 Pod（例如，Deployment） 不同；kubelet 監(jiān)視每個靜態(tài) Pod（在它失敗之后重新啟動）。靜態(tài) Pod 始終都會綁定到特定節(jié)點(diǎn)的 Kubelet 上。

kubelet 會嘗試通過 Kubernetes API 服務(wù)器為每個靜態(tài) Pod 自動創(chuàng)建一個鏡像 Pod。 這意味著節(jié)點(diǎn)上運(yùn)行的靜態(tài) Pod 對 API 服務(wù)來說是可見的，但是不能通過 API 服務(wù)器來控制。 Pod 名稱將把以連字符開頭的節(jié)點(diǎn)主機(jī)名作為后綴。

說明：如果你在運(yùn)行一個 Kubernetes 集群，并且在每個節(jié)點(diǎn)上都運(yùn)行一個靜態(tài) Pod， 就可能需要考慮使用 DaemonSet 替代這種方式。靜態(tài) Pod 的 spec 不能引用其他 API 對象 （如：ServiceAccount、 ConfigMap、 Secret 等）。

3.2 創(chuàng)建靜態(tài)pod

靜態(tài)pod的應(yīng)用場景為：1.使master能正常啟動 2.如果某天我們的master崩潰了，如何讓別人知道我們的服務(wù)器在維護(hù)？
目前該命名空間是沒有pod運(yùn)行的

[root@k8scloude1 pod]# kubectl get pods
No resources found in pod namespace.

靜態(tài)pod的創(chuàng)建方法為：寫一個yaml文件，然后把yaml文件放在指定目錄，會自動根據(jù)yaml文件創(chuàng)建pod。有兩種方法來指定這個目錄：

–pod-manifest-path

/etc/kubernetes/manifests

3.2.1 使用–pod-manifest-path指定靜態(tài)pod目錄

查看kubelet的配置文件位置，可以看到kubelet的配置文件在/usr/lib/systemd/system/kubelet.service

注意：我們是在k8s集群的worker節(jié)點(diǎn)k8scloude2上創(chuàng)建靜態(tài)pod的

[root@k8scloude2 ~]# systemctl status kubelet
● kubelet.service - kubelet: The Kubernetes Node Agent
   Loaded: loaded (/usr/lib/systemd/system/kubelet.service; enabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/kubelet.service.d
           └─10-kubeadm.conf
   Active: active (running) since 六 2022-01-15 12:27:34 CST; 5h 30min ago
     Docs: https://kubernetes.io/docs/
 Main PID: 947 (kubelet)
   Memory: 122.6M
   CGroup: /system.slice/kubelet.service
           └─947 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --config=/var/lib/kubelet/config.yaml --network-plugin=cni --pod-infr...

修改kubelet的配置文件/usr/lib/systemd/system/kubelet.service，使用–pod-manifest-path=/etc/kubernetes/kubelet.d指定靜態(tài)pod目錄。

[root@k8scloude2 ~]# vim /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf 
#--pod-manifest-path=/etc/kubernetes/kubelet.d表示靜態(tài)pod的目錄為/etc/kubernetes/kubelet.d
[root@k8scloude2 ~]# cat /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --pod-manifest-path=/etc/kubernetes/kubelet.d"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS

創(chuàng)建靜態(tài)pod目錄，并使kubelet配置文件生效

[root@k8scloude2 ~]# mkdir /etc/kubernetes/kubelet.d
[root@k8scloude2 ~]# systemctl daemon-reload 
[root@k8scloude2 ~]# systemctl restart kubelet
[root@k8scloude2 ~]# systemctl status kubelet
● kubelet.service - kubelet: The Kubernetes Node Agent
   Loaded: loaded (/usr/lib/systemd/system/kubelet.service; enabled; vendor preset: disabled)
  Drop-In: /usr/lib/systemd/system/kubelet.service.d
           └─10-kubeadm.conf
   Active: active (running) since 六 2022-01-15 18:02:15 CST; 6s ago
     Docs: https://kubernetes.io/docs/
 Main PID: 108844 (kubelet)
   Memory: 30.7M
   CGroup: /system.slice/kubelet.service
           ├─108844 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --pod-manifest-path=/etc/kubernetes/kubelet.d --config=/var/lib/ku...
           └─108999 /usr/bin/kubelet --bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf --pod-manifest-path=/etc/kubernetes/kubelet.d --config=/var/lib/ku...

進(jìn)入靜態(tài)pod的目錄，然后創(chuàng)建pod yaml文件

[root@k8scloude2 ~]# cd /etc/kubernetes/kubelet.d/
[root@k8scloude2 kubelet.d]# ls
[root@k8scloude2 kubelet.d]# vim pod.yaml
[root@k8scloude2 kubelet.d]# cat pod.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod
  name: pod
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod
    resources: {}
    ports:
    - name: http
      containerPort: 80
      protocol: TCP
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

在k8s集群的master節(jié)點(diǎn)上查看pod，在master上可以看到該pod，由于pod.yaml沒有指定namespace，默認(rèn)在default下，可以看到Pod 名稱（pod-k8scloude2）是以連字符開頭的節(jié)點(diǎn)主機(jī)名作為后綴。

[root@k8scloude1 pod]# kubectl get pods -n default -o wide
NAME             READY   STATUS    RESTARTS   AGE    IP               NODE         NOMINATED NODE   READINESS GATES
pod-k8scloude2   1/1     Running   0          109s   10.244.112.153   k8scloude2   <none>           <none>

當(dāng)把這個pod.yaml文件從靜態(tài)pod目錄移走，pod就消失了

[root@k8scloude2 kubelet.d]# mv pod.yaml ~/
[root@k8scloude2 kubelet.d]# ls
#當(dāng)把這個yaml文件移走,pod消失
[root@k8scloude1 pod]# kubectl get pods -n default -o wide
No resources found in default namespace.

現(xiàn)在指定靜態(tài)pod的namespace為pod

[root@k8scloude2 kubelet.d]# vim pod.yaml 
#namespace: pod:指定pod的命名空間
[root@k8scloude2 kubelet.d]# cat pod.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod
  name: pod
  namespace: pod
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod
    resources: {}
    ports:
    - name: http
      containerPort: 80
      protocol: TCP
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
[root@k8scloude2 kubelet.d]# ls
pod.yaml

查看pod

[root@k8scloude1 pod]# kubectl get pods -n pod
NAME             READY   STATUS    RESTARTS   AGE
pod-k8scloude2   1/1     Running   0          6s

3.2.2 靜態(tài)pod默認(rèn)目錄/etc/kubernetes/manifests

注意：進(jìn)行這一步的時候，先還原kubelet配置文件/usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf

查看配置文件，可以發(fā)現(xiàn)靜態(tài)pod默認(rèn)目錄為/etc/kubernetes/manifests

[root@k8scloude2 kubelet.d]# cat /usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf 
# Note: This dropin only works with kubeadm and kubelet v1.11+
[Service]
Environment="KUBELET_KUBECONFIG_ARGS=--bootstrap-kubeconfig=/etc/kubernetes/bootstrap-kubelet.conf --kubeconfig=/etc/kubernetes/kubelet.conf"
Environment="KUBELET_CONFIG_ARGS=--config=/var/lib/kubelet/config.yaml"
# This is a file that "kubeadm init" and "kubeadm join" generates at runtime, populating the KUBELET_KUBEADM_ARGS variable dynamically
EnvironmentFile=-/var/lib/kubelet/kubeadm-flags.env
# This is a file that the user can use for overrides of the kubelet args as a last resort. Preferably, the user should use
# the .NodeRegistration.KubeletExtraArgs object in the configuration files instead. KUBELET_EXTRA_ARGS should be sourced from this file.
EnvironmentFile=-/etc/sysconfig/kubelet
ExecStart=
ExecStart=/usr/bin/kubelet $KUBELET_KUBECONFIG_ARGS $KUBELET_CONFIG_ARGS $KUBELET_KUBEADM_ARGS $KUBELET_EXTRA_ARGS
[root@k8scloude2 kubelet.d]# ls /var/lib/kubelet/config.yaml
/var/lib/kubelet/config.yaml
[root@k8scloude2 kubelet.d]# cat /var/lib/kubelet/config.yaml | grep manifest
staticPodPath: /etc/kubernetes/manifests
#默認(rèn)的靜態(tài)pod的目錄為 ls /etc/kubernetes/manifests
[root@k8scloude2 kubelet.d]# ls /etc/kubernetes/manifests

在默認(rèn)的靜態(tài)pod目錄/etc/kubernetes/manifests/下創(chuàng)建pod yaml文件

#namespace: pod:指定pod的命名空間
[root@k8scloude2 kubelet.d]# vim ~/pod.yaml 
[root@k8scloude2 kubelet.d]# cat ~/pod.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod
  name: pod
  namespace: pod
spec:
  containers:
  - image: nginx
    imagePullPolicy: IfNotPresent
    name: pod
    resources: {}
    ports:
    - name: http
      containerPort: 80
      protocol: TCP
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}
[root@k8scloude2 kubelet.d]# cp ~/pod.yaml /etc/kubernetes/manifests/

可以發(fā)現(xiàn)，靜態(tài)pod已經(jīng)創(chuàng)建了

[root@k8scloude1 pod]# kubectl get pods -n pod
NAME             READY   STATUS    RESTARTS   AGE
pod-k8scloude2   1/1     Running   0          6s

刪除yaml文件，靜態(tài)pod消失

#刪除yaml文件
[root@k8scloude2 kubelet.d]# rm -rf /etc/kubernetes/manifests/pod.yaml 
#pod消失
[root@k8scloude1 pod]# kubectl get pods -n pod
No resources found in pod namespace.

前面幾步，靜態(tài)pod是在k8s集群的worker節(jié)點(diǎn)上做的，現(xiàn)在在k8s集群的master節(jié)點(diǎn)上做。

注意：如果在/usr/lib/systemd/system/kubelet.service.d/10-kubeadm.conf里添加了–pod-manifest-path=/etc/kubernetes/kubelet.d，則相應(yīng)的/etc/kubernetes/manifests/下的yaml文件也要移動到/etc/kubernetes/kubelet.d目錄下，不然k8s集群的master節(jié)點(diǎn)啟動不起來。

可以看到k8s集群的master節(jié)點(diǎn)有很多靜態(tài)pod。

[root@k8scloude1 pod]# ls /etc/kubernetes/manifests/
etcd.yaml  kube-apiserver.yaml  kube-controller-manager.yaml  kube-scheduler.yaml

以上就是靜態(tài)pod 創(chuàng)建使用示例詳解的詳細(xì)內(nèi)容，更多關(guān)于靜態(tài)pod創(chuàng)建使用的資料請關(guān)注其它相關(guān)文章！