k8s基础 ~ 3

k8s研发领域概念

基本概念 - 资源组、资源版本、资源、子资源  -> 表现形式为<group>/<version>/<resource>/<subresource>

比如： apps/v1/deployments/status； apps/v1，Kind=Deployment

常用的资源

类别	名称
工作负载型资源对象	Pod、Replicaset、ReplicationController、Deployments、StatefulSets、Daemonset、Job、CronJob
服务发现及负载均衡	Service、Ingress
配置与存储	Volume、Persistent Volume、CSl 、configmap、secret
集群资源	Namespace、Node、Role、ClusterRole、RoleBinding、ClusterRoleBinding
元数据资源	HPA、PodTemplate、LimitRang

资源又分为内置资源或外部Custom Resource自定义资源

资源之上又有支持的操作 - create、delete、deletecollection、get、list、patch、update、watch

资源列表长啥样

{
  "kind": "APIResourceList",
  "apiVersion": "v1",
  "groupVersion": "metrics.k8s.io/v1beta1",
  "resources": [
    {
      "name": "nodes",
      "singularName": "",
      "namespaced": false,
      "kind": "NodeMetrics",
      "verbs": [
        "get",
        "list"
      ]
    },
    {
      "name": "pods",
      "singularName": "",
      "namespaced": true,
      "kind": "PodMetrics",
      "verbs": [
        "get",
        "list"
      ]
    }
  ]

所以资源都是go的一种types xxx struct结构体，register.go是将资源注册到schema

storage/store操作资源

codec编解码器

pb序列化反序列化

convert转换各个版本

命令执行是怎么玩的？Cobar！也现成的其他包

突然想先看一个源码cmd目录的apiserver文件~

import (
    "math/rand"
    "os"
    "time"

    "github.com/spf13/pflag"

    cliflag "k8s.io/component-base/cli/flag"
    "k8s.io/component-base/logs"
    _ "k8s.io/component-base/logs/json/register"          // for JSON log format registration
    _ "k8s.io/component-base/metrics/prometheus/clientgo" // load all the prometheus client-go plugins
    _ "k8s.io/component-base/metrics/prometheus/version"  // for version metric registration
    "k8s.io/kubernetes/cmd/kube-apiserver/app"
)

func main() {
    rand.Seed(time.Now().UnixNano())

    pflag.CommandLine.SetNormalizeFunc(cliflag.WordSepNormalizeFunc)

    command := app.NewAPIServerCommand()

    logs.InitLogs()
    defer logs.FlushLogs()

    if err := command.Execute(); err != nil {
        os.Exit(1)
    }
}

k8s源码大差不差，套路也类似，启动点基本都是这样，命令实际长这样

func NewAPIServerCommand() *cobra.Command {
    s := options.NewServerRunOptions()
    cmd := &cobra.Command{
        Use: "kube-apiserver",
        Long: `The Kubernetes API server validates and configures data
for the api objects which include pods, services, replicationcontrollers, and
others. The API Server services REST operations and provides the frontend to the
cluster's shared state through which all other components interact.`,

        // stop printing usage when the command errors
        SilenceUsage: true,
        PersistentPreRunE: func(*cobra.Command, []string) error {
            // silence client-go warnings.
            // kube-apiserver loopback clients should not log self-issued warnings.
            rest.SetDefaultWarningHandler(rest.NoWarnings{})
            return nil
        },
        RunE: func(cmd *cobra.Command, args []string) error {
            verflag.PrintAndExitIfRequested()
            fs := cmd.Flags()
            cliflag.PrintFlags(fs)

            err := checkNonZeroInsecurePort(fs)
            if err != nil {
                return err
            }
            // set default options
            completedOptions, err := Complete(s)
            if err != nil {
                return err
            }

            // validate options
            if errs := completedOptions.Validate(); len(errs) != 0 {
                return utilerrors.NewAggregate(errs)
            }

            return Run(completedOptions, genericapiserver.SetupSignalHandler())
        },
        Args: func(cmd *cobra.Command, args []string) error {
            for _, arg := range args {
                if len(arg) > 0 {
                    return fmt.Errorf("%q does not take any arguments, got %q", cmd.CommandPath(), args)
                }
            }
            return nil
        },
    }

    fs := cmd.Flags()
    namedFlagSets := s.Flags()
    verflag.AddFlags(namedFlagSets.FlagSet("global"))
    globalflag.AddGlobalFlags(namedFlagSets.FlagSet("global"), cmd.Name())
    options.AddCustomGlobalFlags(namedFlagSets.FlagSet("generic"))
    for _, f := range namedFlagSets.FlagSets {
        fs.AddFlagSet(f)
    }

    cols, _, _ := term.TerminalSize(cmd.OutOrStdout())
    cliflag.SetUsageAndHelpFunc(cmd, namedFlagSets, cols)

    return cmd
}