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node 也就是安裝/執行 k8s 的 hardware source
可以是 VM 也可以是 Bare Metal
先告訴大家
不同的 k8s distribution 會有不同的 add node 方式
除非你是採用 原生的 k8s
不然這邊快速了解就好
如果你是採用 cloud provider 的 k8s cluster
沒意外都是 colsole 點個兩下即可
for on-premise
要新增 node 有兩種方式
要注意 node name 預設是 host name, 且在 k8s cluster 必須 unique 不能重複
kubectl: 操作 k8s 的工具, 後面會介紹
這邊用到一些指令
但因為還沒講 kubectl
所以大概知道就好
# check node status
kubectl describe node
前面有說, kubectl 是我們對 k8s 的操作工具
describe node 就是取得 node 的資訊
比如說 node ip, 執行在該 node 的 pod
cpu/memory resource usage
範例
$ k describe node node1
Name: node1
Roles: control-plane,etcd,master
Labels: beta.kubernetes.io/arch=amd64
beta.kubernetes.io/instance-type=k3s
beta.kubernetes.io/os=linux
kubernetes.io/arch=amd64
kubernetes.io/hostname=node1
kubernetes.io/os=linux
node-role.kubernetes.io/control-plane=true
node-role.kubernetes.io/etcd=true
node-role.kubernetes.io/master=true
node.kubernetes.io/instance-type=k3s
p2p.k3s.cattle.io/enabled=true
Annotations: alpha.kubernetes.io/provided-node-ip: 192.168.56.101,fd17:625c:f037:2:a00:27ff:fe94:112e
csi.volume.kubernetes.io/nodeid: {"driver.longhorn.io":"node1"}
etcd.k3s.cattle.io/local-snapshots-timestamp: 2025-06-17T07:07:56Z
etcd.k3s.cattle.io/node-address: 192.168.56.101
etcd.k3s.cattle.io/node-name: node1-0d481970
k3s.io/hostname: node1
k3s.io/internal-ip: 192.168.56.101,fd17:625c:f037:2:a00:27ff:fe94:112e
k3s.io/node-args:
["server","--disable","traefik","--write-kubeconfig-mode","644","--cluster-init","--tls-san","192.168.56.100","--flannel-backend","none","...
k3s.io/node-config-hash: 3YGRMKVSKKIFXYFIXWEHZNCZIVK6HVSSOA5N7TVZOS737YFETYAA====
k3s.io/node-env: {}
node.alpha.kubernetes.io/ttl: 0
p2p.k3s.cattle.io/node-address: /ip4/192.168.56.101/tcp/5001/p2p/QmdFujBrJdhruLKp9Cop3DyFcciJmam3WTqW5cbykJjhhz
volumes.kubernetes.io/controller-managed-attach-detach: true
CreationTimestamp: Sat, 14 Jun 2025 08:36:06 +0000
Taints: <none>
Unschedulable: false
Lease:
HolderIdentity: node1
AcquireTime: <unset>
RenewTime: Tue, 17 Jun 2025 07:08:16 +0000
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
NetworkUnavailable False Sat, 14 Jun 2025 08:45:49 +0000 Sat, 14 Jun 2025 08:45:49 +0000 CiliumIsUp Cilium is running on this node
EtcdIsVoter True Tue, 17 Jun 2025 07:08:05 +0000 Sat, 14 Jun 2025 08:36:11 +0000 MemberNotLearner Node is a voting member of the etcd cluster
MemoryPressure False Tue, 17 Jun 2025 07:07:56 +0000 Sat, 14 Jun 2025 08:36:06 +0000 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Tue, 17 Jun 2025 07:07:56 +0000 Sat, 14 Jun 2025 08:36:06 +0000 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Tue, 17 Jun 2025 07:07:56 +0000 Sat, 14 Jun 2025 08:36:06 +0000 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Tue, 17 Jun 2025 07:07:56 +0000 Sat, 14 Jun 2025 08:45:56 +0000 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 192.168.56.101
InternalIP: fd17:625c:f037:2:a00:27ff:fe94:112e
Hostname: node1
Capacity:
cpu: 2
ephemeral-storage: 61608748Ki
hugepages-2Mi: 0
memory: 4010048Ki
pods: 110
Allocatable:
cpu: 2
ephemeral-storage: 59932990008
hugepages-2Mi: 0
memory: 4010048Ki
pods: 110
System Info:
Machine ID: 9f6371c13b0749708493e43754b8116c
System UUID: c5ae2699-ab20-9440-bc68-7c08b1f869e0
Boot ID: 9383dce5-abe9-4ad2-8a0e-82f5a0b96b7d
Kernel Version: 6.8.0-60-generic
OS Image: Ubuntu 24.04.2 LTS
Operating System: linux
Architecture: amd64
Container Runtime Version: containerd://2.0.5-k3s1.32
Kubelet Version: v1.32.5+k3s1
Kube-Proxy Version: v1.32.5+k3s1
PodCIDR: 10.42.0.0/24
PodCIDRs: 10.42.0.0/24
ProviderID: k3s://node1
Non-terminated Pods: (26 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits Age
--------- ---- ------------ ---------- --------------- ------------- ---
haproxy-controller haproxy-kubernetes-ingress-67b459d7f8-8h9mn 250m (12%) 0 (0%) 400Mi (10%) 0 (0%) 2d22h
haproxy-controller haproxy-kubernetes-ingress-67b459d7f8-zs5g5 250m (12%) 0 (0%) 400Mi (10%) 0 (0%) 2d22h
kube-system cilium-envoy-slwh6 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
kube-system cilium-nl6xt 100m (5%) 0 (0%) 10Mi (0%) 0 (0%) 2d22h
kube-system cilium-operator-5444dfc444-2wttm 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
kube-system coredns-697968c856-9dm6b 100m (5%) 0 (0%) 70Mi (1%) 170Mi (4%) 2d22h
kube-system local-path-provisioner-774c6665dc-fbklx 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
kube-system metrics-server-6f4c6675d5-62p4b 100m (5%) 0 (0%) 70Mi (1%) 0 (0%) 2d22h
longhorn-system csi-attacher-5d68b48d9-64n7m 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-attacher-5d68b48d9-m2qk6 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-attacher-5d68b48d9-p7pf2 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-provisioner-6fcc6478db-4r4cs 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-provisioner-6fcc6478db-gzczt 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-provisioner-6fcc6478db-xl85j 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-resizer-6c558c9fbc-hkhwh 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-resizer-6c558c9fbc-lcm5w 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-resizer-6c558c9fbc-n87lw 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-snapshotter-874b9f887-8p2rl 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-snapshotter-874b9f887-pqv2f 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system csi-snapshotter-874b9f887-rkjr4 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system engine-image-ei-e09d8caa-dcgp2 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system longhorn-csi-plugin-chngl 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system longhorn-driver-deployer-54599c447c-w8fs6 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system longhorn-manager-6ffpt 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system longhorn-ui-6b44759848-glhbh 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
longhorn-system longhorn-ui-6b44759848-jqlp5 0 (0%) 0 (0%) 0 (0%) 0 (0%) 2d22h
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 800m (40%) 0 (0%)
memory 950Mi (24%) 170Mi (4%)
ephemeral-storage 0 (0%) 0 (0%)
hugepages-2Mi 0 (0%) 0 (0%)
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Starting 27s kubelet Starting kubelet.
Normal NodeAllocatableEnforced 26s kubelet Updated Node Allocatable limit across pods
Normal NodeHasSufficientMemory 26s kubelet Node node1 status is now: NodeHasSufficientMemory
Normal NodeHasNoDiskPressure 26s kubelet Node node1 status is now: NodeHasNoDiskPressure
Normal NodeHasSufficientPID 26s kubelet Node node1 status is now: NodeHasSufficientPID
Warning Rebooted 26s kubelet Node node1 has been rebooted, boot id: 9383dce5-abe9-4ad2-8a0e-82f5a0b96b7d
Normal NodePasswordValidationComplete 26s k3s-supervisor Deferred node password secret validation complete
Normal RegisteredNode 14s node-controller Node node1 event: Registered Node node1 in Controller
從範例中可以看到其實資訊蠻細的
所以要看 status 就是記得下 describe 就對了
就是在說 control plane 會 monitor node status, default every 5 seconds
如果 node 失連
scheduler 會避開該 node schedule(編排) pod
既有的 pod 也會 evict(驅逐) (重新 schedule 在其他 node)
如果今天想要對 node 進行維護
我們可以讓 node 進入 unschedulable 狀態
這是告訴 scheduler 不要再 schedule(編排)新的 pod 到該 node 上
但是既有的 pod 不會受到影響
kubectl cordon <node name>
接著在 node status 就可以看到 STATUS: SchedulingDisabled
$ k get node
NAME STATUS ROLES AGE VERSION
node4 Ready,SchedulingDisabled <none> 2d22h v1.32.5+k3s1
要復原就是讓 node status 變回 schedulable 狀態
kubectl uncordon <node name>
drain 與 cordon 很像
不過他更進一步執行 evict(驅逐) 該 node 身上的 pod
也就是讓 node 完全沒有 user workload
可以直接對 node 執行 drain, k8s 會先執行 cordon 才做 evict
不會讓你發生一邊在 evict(驅逐) 又一邊再 schedule(編排) 新的 pod 進來
這邊通常會加上 --ignore-daemonsets
後面會再說明 daemonsets 是什麼
kubectl drain --ignore-daemonsets <node name>
要復原就是讓 node status 變回 schedulable 狀態
kubectl uncordon <node name>
如果這個 node 不要了
就是下
kubectl delete <node name>
以上稍微介紹 node 基本管理知識
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