Kubernetes Pod 运行方式与故障排查思路
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Kubernetes（持续更新中）
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1311 字
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20 分钟
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一、容器的类型

  1. 基础架构容器
    • 优先于业务容器启动，负责名称空间的初始化工作。
    • 共享 ipc、net、time、user 四个名称空间。
  2. 初始化容器
    • 在基础架构容器之后、业务容器之前运行。
    • 用于为业务容器做初始化工作，所有初始化容器执行完毕后才会启动业务容器。
  3. 业务容器
    • 实际用户运行的容器，与业务直接相关。

Tips：

  • 删除业务容器时，Pod 的 IP 地址不变。
  • 删除基础架构容器时，IP 地址会变动。
  • 启动顺序：基础架构容器 > 初始化容器 > 业务容器。

二、Pod 故障排查思路

  1. kubectl describe
    • 用于查看 Pod 的详细信息，包括事件日志。
    bash复制kubectl describe pod <pod-name>
  2. kubectl logs
    • 查看容器日志。
    bash复制kubectl logs <pod-name> -c <container-name>
  3. kubectl exec
    • 在容器中执行命令或进入容器交互。
    bash复制kubectl exec -it <pod-name> -c <container-name> -- <command>
  4. kubectl cp
    • 拷贝文件到容器或从容器中拷贝文件。
    bash复制kubectl cp <pod-name>:/path/to/file /local/path
  5. kubectl explain
    • 查看 Kubernetes 资源字段的含义。
    bash复制kubectl explain Pod.spec.containers.command
  6. command & args
    • 替换容器的默认启动命令或参数。

三、Pod 的重启策略

  • Always：无论容器是否正常退出，始终重启。
  • Never：无论容器是否正常退出，始终不重启。
  • OnFailure：仅在容器异常退出时重启。

四、常见控制器

  • rc：ReplicationController
  • rs：ReplicaSet
  • deploy：Deployment
  • ds：DaemonSet
  • jobs：Job
  • cj：CronJob

五、部署案例

1. GitLab

  • 镜像：gitlab/gitlab-ce:17.5.2-ce.0
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-casedemo-gitlab
  labels:
    apps: gitlab
spec:
  hostNetwork: true
  restartPolicy: Always
  nodeName: worker233
  containers:
  - name: c1
    image: gitlab/gitlab-ce:17.5.2-ce.0
    ports:
    - containerPort: 80
  • 访问：http://<Node-IP>/
  • 初始密码：kubectl exec <pod-name> -- cat /etc/gitlab/initial_root_password

2. Jenkins

  • 镜像：jenkins/jenkins:2.479.1-alpine-jdk21
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-casedemo-jenkins
  labels:
    apps: jenkins
spec:
  hostNetwork: true
  restartPolicy: Always
  nodeName: worker233
  containers:
  - name: c1
    image: jenkins/jenkins:2.479.1-alpine-jdk21
    ports:
    - containerPort: 8080
  • 访问：http://<Node-IP>:8080/
  • 初始密码：kubectl logs -f <pod-name>

3. SonarQube

  • 镜像：sonarqube:9.9.7-community
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-casedemo-sonarqube
  labels:
    apps: sonarqube
spec:
  hostNetwork: true
  restartPolicy: Always
  nodeName: worker233
  containers:
  - name: c1
    image: sonarqube:9.9.7-community
    ports:
    - containerPort: 9000
  • 访问：http://<Node-IP>:9000/
  • 默认用户名：admin，密码：admin

4. MySQL

  • 镜像：mysql:8.0.36-oracle
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-casedemo-mysql-env
  labels:
    apps: mysql
spec:
  hostNetwork: true
  restartPolicy: Always
  nodeName: worker233
  containers:
  - name: c1
    image: mysql:8.0.36-oracle
    args:
    - --character-set-server=utf8
    - --collation-server=utf8_bin
    - --default-authentication-plugin=mysql_native_password
    ports:
    - containerPort: 3306
    env:
    - name: MYSQL_ALLOW_EMPTY_PASSWORD
      value: "yes"
    - name: MYSQL_DATABASE
      value: oldboyedu
    - name: MYSQL_USER
      value: linux95
    - name: MYSQL_PASSWORD
      value: "123456"
  • 访问：kubectl exec -it <pod-name> -- mysql

5. WordPress

  • 镜像：wordpress:6.7.1-php8.1-apache
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-casedemo-wp
  labels:
    apps: mysql
spec:
  hostNetwork: true
  restartPolicy: Always
  nodeName: worker232
  containers:
  - name: c1
    image: wordpress:6.7.1-php8.1-apache
    ports:
    - containerPort: 80
    env:
    - name: WORDPRESS_DB_HOST
      value: <MySQL-Node-IP>
    - name: WORDPRESS_DB_NAME
      value: oldboyedu
    - name: WORDPRESS_DB_USER
      value: linux95
    - name: WORDPRESS_DB_PASSWORD
      value: "123456"
  • 访问：http://<Node-IP>/

6. Elasticsearch

  • 镜像：docker.elastic.co/elasticsearch/elasticsearch:7.17.24
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-single-es
  labels:
    apps: es7
spec:
  hostNetwork: true
  nodeName: worker232
  containers:
  - name: c1
    image: docker.elastic.co/elasticsearch/elasticsearch:7.17.24
    ports:
    - containerPort: 9200
      name: http
    - containerPort: 9300
      name: tcp
    env:
    - name: discovery.type
      value: single-node
    - name: cluster.name
      value: oldboyedu-linux95
    - name: ES_JAVA_OPTS
      value: -Xms256m -Xmx256m
  • 访问：http://<Node-IP>:9200/

7. Kibana

  • 镜像：docker.elastic.co/kibana/kibana:7.17.24
  • 资源清单：

yaml复制

apiVersion: v1
kind: Pod
metadata:
  name: oldboyedu-kibana
  labels:
    apps: kibana
spec:
  hostNetwork: true
  nodeName: worker233
  containers:
  - name: c1
    image: docker.elastic.co/kibana/kibana:7.17.24
    ports:
    - containerPort: 5601
      name: webui
    env:
    - name: ELASTICSEARCH_HOSTS
      value: http://<Elasticsearch-Node-IP>:9200
    - name: I18N_LOCALE
      value: zh-CN
  • 访问：http://<Node-IP>:5601/

常见控制器

rc（ReplicationController）

  • 概述：控制指定 Pod 副本数量始终存活。
  • 实战案例yaml复制apiVersion: v1 kind: ReplicationController metadata: name: oldboyedu-rc labels: school: oldboyedu spec: replicas: 3 selector: apps: xiuxian address: shahe template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
  • 操作
    • 创建资源：kubectl apply -f 01-rc-xiuxian.yaml
    • 删除 Pod 观察副本自动拉起
    • 删除 rc 资源会级联删除其创建的 Pod

rs（ReplicaSet）

  • 概述：与 rc 功能类似，但更轻量级，功能更完善。
  • 实战案例yaml复制apiVersion: apps/v1 kind: ReplicaSet metadata: name: rs-xiuxian labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
  • 操作
    • 创建资源：kubectl apply -f 01-rs-matchLabels-xiuxian.yaml
    • 测试 rs 的高级功能（如 matchExpressions）

deploy（Deployment）

  • 概述：基于 rs 实现 Pod 副本控制，支持声明式更新。
  • 实战案例yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
  • 操作
    • 创建资源：kubectl apply -f 01-deploy-matchLabels-xiuxian.yaml
    • 删除 rs 或 Pod 观察自动重建

ds（DaemonSet）

  • 概述：每个 worker 节点有且仅有一个 Pod 运行。
  • 实战案例yaml复制apiVersion: apps/v1 kind: DaemonSet metadata: name: ds-xiuxian labels: school: oldboyedu spec: selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1
  • 操作
    • 创建资源：kubectl apply -f 01-ds-xiuxian.yaml

jobs

  • 概述：用于实现一次性任务。
  • 实战案例yaml复制apiVersion: batch/v1 kind: Job metadata: name: jobs-xiuxian labels: school: oldboyedu spec: template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: restartPolicy: OnFailure containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1 command: - sleep - "5"
  • 操作
    • 创建资源：kubectl apply -f 01-jobs-xiuxian.yaml

cj（CronJob）

  • 概述：基于 jobs 实现周期性任务。
  • 实战案例yaml复制apiVersion: batch/v1 kind: CronJob metadata: name: cj-xiuxian labels: school: oldboyedu spec: schedule: "* * * * *" jobTemplate: spec: template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: restartPolicy: Never containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1 command: - /bin/sh - -c - date -R; echo "学IT来老男孩，月薪过万不是梦~"
  • 操作
    • 创建资源：kubectl apply -f 01-cj-xiuxian.yaml

玩转 Pod 调度

nodeName

  • 实战案例yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-nodename labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: nodeName: worker233 containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1

hostPort

  • 实战案例yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-ports labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1 ports: - containerPort: 80 hostPort: 81

hostNetwork

  • 实战案例yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-hostnetwork labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: hostNetwork: true containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1 ports: - containerPort: 80

resources（资源限制）

  • requests（期望资源）yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-resources labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: jasonyin2020/oldboyedu-linux-tools:v0.1 stdin: true resources: requests: cpu: 0.5 memory: 10G
  • limits（资源上限）yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-resources-limits labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: containers: - name: c1 image: jasonyin2020/oldboyedu-linux-tools:v0.1 stdin: true resources: limits: cpu: 0.5 memory: 2G requests: cpu: 200m memory: 1G

nodeSelector（基于节点标签调度）

  • 实战案例yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-nodeselector labels: school: oldboyedu spec: replicas: 5 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: nodeSelector: school: laonanhai containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1

taints（污点）与 tolerations（容忍）

  • taints
    • 格式：key[=value]:effect
    • effect 类型：
      • NoSchedule：不接受新 Pod，但不驱逐现有 Pod。
      • PreferNoSchedule：尽量避免调度到该节点。
      • NoExecute：不接受新 Pod，并驱逐现有 Pod。
    • 操作
      • 查看污点：kubectl describe nodes <node-name> | grep Taints
      • 打污点：kubectl taint node <node-name> key=value:effect
      • 删除污点：kubectl taint node <node-name> key-
      • 修改污点：kubectl taint node <node-name> key=value:effect --overwrite
  • tolerations
    • Pod 需要容忍节点的污点才能调度。
    • 示例：yaml复制apiVersion: apps/v1 kind: Deployment metadata: name: deploy-xiuxian-tolerations labels: school: oldboyedu spec: replicas: 10 selector: matchLabels: apps: xiuxian template: metadata: labels: apps: xiuxian address: shahe class: linux95 spec: tolerations: - key: node-role.kubernetes.io/master effect: NoSchedule operator: Equal - key: school value: laonanhai effect: NoExecute operator: Equal containers: - name: c1 image: registry.cn-hangzhou.aliyuncs.com/yinzhengjie-k8s/apps:v1 resources: requests: cpu: 0.2 memory: 500Mi

cordon/uncordon（标记不可调度/取消不可调度）

  • cordon
    • 标记节点不可调度，同时打污点。
    • 示例：kubectl cordon <node-name>
  • uncordon
    • 取消不可调度。
    • 示例：kubectl uncordon <node-name>

drain（驱逐 Pod）

  • 功能：驱逐节点上的 Pod，便于维护。
  • 操作：kubectl drain <node-name> --ignore-daemonsets

项目案例

K8S 集群缩容

  1. 驱逐 Pod：kubectl drain <node-name> --ignore-daemonsets
  2. 停止 kubelet：systemctl disable --now kubelet
  3. 重置环境：kubeadm reset -f
  4. 删除节点：kubectl delete nodes <node-name>

K8S 集群扩容

  1. 创建 token：kubeadm token create <token-name> --ttl 0 --print-join-command
  2. 环境准备：禁用 swap，安装软件包等。
  3. 启动 kubelet：systemctl enable kubelet.service
  4. 加入集群：在 worker 节点执行 kubeadm join 命令。
  5. 验证节点加入：kubectl get nodes
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