Kubernetes学习实践（二） -- 熟悉K8S相关概念和实操印证
继续熟悉K8S的相关概念，并实操印证增强理解和体感
Kubernetes学习实践（二） -- 熟悉K8S相关概念和实操印证
1. 引言
上篇搭建了一个单机K8S环境，本篇基于环境进行操作印证，熟悉理解相关概念和操作命令。
2. 基本操作命令
下述相关命令结果详情，可见：kubectl_cmd_operation.md。
2.1. 查看节点/Pod的状态和细节信息
命令：kubectl describe TYPE NAME_PREFIX，其中名称支持前缀模糊匹配
- 查看节点详细信息，
kubectl describe node xdlinux- 由于支持名称前缀匹配，也可以
kubectl describe node xd查看到xdlinux节点的信息 kubectl describe node、kubectl describe nodes也查询了到节点详情信息
- 由于支持名称前缀匹配，也可以
- 除此之外，
TYPE还可以是pod、pods，进一步信息可以kubectl describe -h查看
关键信息：
- 地址，下述的
Addresses部分InternalIP: 192.168.1.150Hostname: xdlinux
- 状况，
Conditions，描述所有Running节点的状态- 如下述展示的几类状态：
MemoryPressure内存压力、DiskPressure磁盘压力、PIDPressure进程压力、Ready：true表示节点健康，可接收Pod - 每种类型都有：当前的状态和状态发生变化的时间、出现该状态的原因信息
- 当节点出现问题时，K8S会自动创建和相应状态的 污点（Taint） ，其和节点的 亲和性（affinity）相反，使节点排斥一类特定的Pod。
- 如下述展示的几类状态：
- 容量（
Capacity）和可分配（Allocatable）- 这两个值描述节点上的可用资源：CPU、内存和可以调度到节点上的 Pod 的个数上限
- 信息（
Info）- 节点的一般信息，如内核版本、Kubernetes 版本（kubelet 和 kube-proxy 版本）、 容器运行时详细信息，以及节点使用的操作系统。
kubelet从节点收集这些信息并将其发布到 Kubernetes API
- 进一步的信息，可见：节点状态。
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[root@xdlinux ➜ hello git:(main) ]$ kubectl describe node xdlinux
Name: xdlinux
Roles: control-plane
Labels: beta.kubernetes.io/arch=amd64
...
CreationTimestamp: Mon, 21 Jul 2025 07:47:52 +0800
Taints: node-role.kubernetes.io/control-plane:NoSchedule
Unschedulable: false
Lease:
HolderIdentity: xdlinux
AcquireTime: <unset>
RenewTime: Tue, 22 Jul 2025 22:57:36 +0800
Conditions:
Type Status LastHeartbeatTime LastTransitionTime Reason Message
---- ------ ----------------- ------------------ ------ -------
MemoryPressure False Tue, 22 Jul 2025 22:57:34 +0800 Mon, 21 Jul 2025 07:47:51 +0800 KubeletHasSufficientMemory kubelet has sufficient memory available
DiskPressure False Tue, 22 Jul 2025 22:57:34 +0800 Mon, 21 Jul 2025 07:47:51 +0800 KubeletHasNoDiskPressure kubelet has no disk pressure
PIDPressure False Tue, 22 Jul 2025 22:57:34 +0800 Mon, 21 Jul 2025 07:47:51 +0800 KubeletHasSufficientPID kubelet has sufficient PID available
Ready True Tue, 22 Jul 2025 22:57:34 +0800 Tue, 22 Jul 2025 20:08:06 +0800 KubeletReady kubelet is posting ready status
Addresses:
InternalIP: 192.168.1.150
Hostname: xdlinux
Capacity:
cpu: 16
ephemeral-storage: 56872Mi
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 31929508Ki
pods: 110
Allocatable:
cpu: 16
ephemeral-storage: 53671152756
hugepages-1Gi: 0
hugepages-2Mi: 0
memory: 31827108Ki
pods: 110
System Info:
Machine ID: fedf1414bf654cf090067b7374c2a61a
System UUID: 3adbd480-702c-11ec-8165-1ad318f15100
Boot ID: 28911b0d-93b1-4ba3-9f90-4d3c61270498
Kernel Version: 5.14.0-503.40.1.el9_5.x86_64
OS Image: Rocky Linux 9.5 (Blue Onyx)
Operating System: linux
Architecture: amd64
Container Runtime Version: containerd://2.1.3
Kubelet Version: v1.33.3
Kube-Proxy Version:
PodCIDR: 10.244.0.0/24
PodCIDRs: 10.244.0.0/24
Non-terminated Pods: (7 in total)
Namespace Name CPU Requests CPU Limits Memory Requests Memory Limits Age
--------- ---- ------------ ---------- --------------- ------------- ---
kube-system coredns-757cc6c8f8-nxw7g 100m (0%) 0 (0%) 70Mi (0%) 170Mi (0%) 39h
kube-system coredns-757cc6c8f8-v2mgf 100m (0%) 0 (0%) 70Mi (0%) 170Mi (0%) 39h
kube-system etcd-xdlinux 100m (0%) 0 (0%) 100Mi (0%) 0 (0%) 39h
kube-system kube-apiserver-xdlinux 250m (1%) 0 (0%) 0 (0%) 0 (0%) 39h
kube-system kube-controller-manager-xdlinux 200m (1%) 0 (0%) 0 (0%) 0 (0%) 39h
kube-system kube-proxy-v682x 0 (0%) 0 (0%) 0 (0%) 0 (0%) 39h
kube-system kube-scheduler-xdlinux 100m (0%) 0 (0%) 0 (0%) 0 (0%) 39h
Allocated resources:
(Total limits may be over 100 percent, i.e., overcommitted.)
Resource Requests Limits
-------- -------- ------
cpu 850m (5%) 0 (0%)
memory 240Mi (0%) 340Mi (1%)
ephemeral-storage 0 (0%) 0 (0%)
hugepages-1Gi 0 (0%) 0 (0%)
hugepages-2Mi 0 (0%) 0 (0%)
Events: <none>
3. 小结
4. 参考
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