你插件中的kubectl標誌

• 2019 年 12 月 4 日
• 筆記

之前由Gianluca Arbezzano在Gianarb.it上發布

這不是一個新的話題，不涉及hacking，但它是每個在設計kubectl插件的人都需要知道。

我最近就在開發一個，必須讓用戶體驗與kubectl相比儘可能友好，因為這是一個好的所要做的事！欺騙其他開發人員，使他們的生活舒適，如果你習慣這樣做：

$ kubectl get pod -n your-namespace -L app=http

要從一個特定的命名空間your-namespace獲取pod，被標籤app=http過濾，要是你的插件也做類似的事情，它將受益於這歌經典get的交互方式，你應該重用這些標誌。

示例：設計一個kubectl-plugin，能夠對一組容器運行pprof。

我的期望是：

$ kubectl pprof -n your-namespace -n pod-name-go-app

Kubernetes社區用Go編寫了很多程式碼，這意味著有很多庫可以重用。

kubernetes/cli-runtime是一個庫，它提供了創建kubectl插件的實用工具。他們的一個包叫做genericclioptions，你可以從它的名字中知道，它的目標是顯而易見的。

https://github.com/kubernetes/cli-runtime/tree/master/pkg/genericclioptions

// import "github.com/spf13/cobra"  // import "github.com/spf13/pflag"  // import "k8s.io/cli-runtime/pkg/genericclioptions"    // Create the set of flags for your kubect-plugin  flags := pflag.NewFlagSet("kubectl-plugin", pflag.ExitOnError)  pflag.CommandLine = flags    // Configure the genericclioptions  streams := genericclioptions.IOStreams{      In:     os.Stdin,      Out:    os.Stdout,      ErrOut: os.Stderr,  }    // This set of flags is the one used for the kubectl configuration such as:  // cache-dir, cluster-name, namespace, kube-config, insecure, timeout, impersonate,  // ca-file and so on  kubeConfigFlags := genericclioptions.NewConfigFlags(false)    // It is a set of flags related to a specific resource such as: label selector  (-L), --all-namespaces, --schema and so on.  kubeResouceBuilderFlags := genericclioptions.NewResourceBuilderFlags()    var rootCmd = &cobra.Command{      Use:   "kubectl-plugin",      Short: "My root command",      Run: func(cmd *cobra.Command, args []string) {  cmd.SetOutput(streams.ErrOut)      }  }    // You can join all this flags to your root command  flags.AddFlagSet(rootCmd.PersistentFlags())  kubeConfigFlags.AddFlags(flags)  kubeResouceBuilderFlags.AddFlags(flags)

這是輸出：

$ kubectl-plugin --help  My root command    Usage:    kubectl-plugin [flags]    Flags:        --as string                      Username to impersonate for the operation        --as-group stringArray           Group to impersonate for the operation, this flag can be repeated to specify multiple groups.        --cache-dir string               Default HTTP cache directory (default "/home/gianarb/.kube/http-cache")        --certificate-authority string   Path to a cert file for the certificate authority        --client-certificate string      Path to a client certificate file for TLS        --client-key string              Path to a client key file for TLS        --cluster string                 The name of the kubeconfig cluster to use        --context string                 The name of the kubeconfig context to use    -f, --filename strings               identifying the resource.    -h, --help                           help for kubectl-pprof        --insecure-skip-tls-verify       If true, the server's certificate will not be checked for validity. This will make your HTTPS connections insecure        --kubeconfig string              Path to the kubeconfig file to use for CLI requests.    -n, --namespace string               If present, the namespace scope for this CLI request    -R, --recursive                      Process the directory used in -f, --filename recursively. Useful when you want to manage related manifests organized within the same directory. (default true)        --request-timeout string         The length of time to wait before giving up on a single server request. Non-zero values should contain a corresponding time unit (e.g. 1s, 2m, 3h). A value of zero means don't timeout requests. (default "0")    -l, --selector string                Selector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2)    -s, --server string                  The address and port of the Kubernetes API server        --token string                   Bearer token for authentication to the API server        --user string                    The name of the kubeconfig user to use