kubectl源码分析之config get-contexts

深碍√TFBOYSˉ_ 2023-02-21 14:21 75阅读 0赞

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![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAaHhwamF2YTE_size_8_color_FFFFFF_t_70_g_se_x_16][]

目前刚开始写一个月，一共写了18篇原创文章，文章目录如下：

[istio多集群探秘，部署了50次多集群后我得出的结论][istio_50]

[istio多集群链路追踪，附实操视频][istio]

[istio防故障利器，你知道几个,istio新手不要读，太难！][istio_istio]

[istio业务权限控制，原来可以这么玩][istio 1]

[istio实现非侵入压缩，微服务之间如何实现压缩][istio 2]

[不懂envoyfilter也敢说精通istio系列-http-rbac-不要只会用AuthorizationPolicy配置权限][envoyfilter_istio_-http-rbac-_AuthorizationPolicy]

[不懂envoyfilter也敢说精通istio系列-02-http-corsFilter-不要只会vs][envoyfilter_istio_-02-http-corsFilter-_vs]

[不懂envoyfilter也敢说精通istio系列-03-http-csrf filter-再也不用再代码里写csrf逻辑了][envoyfilter_istio_-03-http-csrf filter-_csrf]

[不懂envoyfilter也敢说精通istio系列http-jwt\_authn-不要只会RequestAuthorization][envoyfilter_istio_http-jwt_authn-_RequestAuthorization]

[不懂envoyfilter也敢说精通istio系列-05-fault-filter-故障注入不止是vs][envoyfilter_istio_-05-fault-filter-_vs]

[不懂envoyfilter也敢说精通istio系列-06-http-match-配置路由不只是vs][envoyfilter_istio_-06-http-match-_vs]

[不懂envoyfilter也敢说精通istio系列-07-负载均衡配置不止是dr][envoyfilter_istio_-07-_dr]

[不懂envoyfilter也敢说精通istio系列-08-连接池和断路器][envoyfilter_istio_-08-]

[不懂envoyfilter也敢说精通istio系列-09-http-route filter][envoyfilter_istio_-09-http-route filter]

[不懂envoyfilter也敢说精通istio系列-network filter-redis proxy][envoyfilter_istio_-network filter-redis proxy]

[不懂envoyfilter也敢说精通istio系列-network filter-HttpConnectionManager][envoyfilter_istio_-network filter-HttpConnectionManager]

[不懂envoyfilter也敢说精通istio系列-ratelimit-istio ratelimit完全手册][envoyfilter_istio_-ratelimit-istio ratelimit]

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type GetContextsOptions struct {//get-contexts结构体
    	configAccess clientcmd.ConfigAccess
    	nameOnly     bool
    	showHeaders  bool
    	contextNames []string
    
    	genericclioptions.IOStreams
    }

//创建get-contexts命令
    func NewCmdConfigGetContexts(streams genericclioptions.IOStreams, configAccess clientcmd.ConfigAccess) *cobra.Command {
    	options := &GetContextsOptions{//初始化结构体
    		configAccess: configAccess,
    
    		IOStreams: streams,
    	}
    
    	cmd := &cobra.Command{//创建cobra命令
    		Use:                   "get-contexts [(-o|--output=)name)]",
    		DisableFlagsInUseLine: true,
    		Short:                 i18n.T("Describe one or many contexts"),
    		Long:                  getContextsLong,
    		Example:               getContextsExample,
    		Run: func(cmd *cobra.Command, args []string) {
    			validOutputTypes := sets.NewString("", "json", "yaml", "wide", "name", "custom-columns", "custom-columns-file", "go-template", "go-template-file", "jsonpath", "jsonpath-file")//有效的输出格式
    			supportedOutputTypes := sets.NewString("", "name")//支持的输出格式
    			outputFormat := cmdutil.GetFlagString(cmd, "output")//获取输出格式
    			if !validOutputTypes.Has(outputFormat) {//判断输出是否有效
    				cmdutil.CheckErr(fmt.Errorf("output must be one of '' or 'name': %v", outputFormat))
    			}
    			if !supportedOutputTypes.Has(outputFormat) {.//判断输出是否支持
    				fmt.Fprintf(options.Out, "--output %v is not available in kubectl config get-contexts; resetting to default output format\n", outputFormat)
    				cmd.Flags().Set("output", "")
    			}
    			cmdutil.CheckErr(options.Complete(cmd, args))//准备
    			cmdutil.CheckErr(options.RunGetContexts())//运行
    		},
    	}
    
    	cmd.Flags().Bool("no-headers", false, "When using the default or custom-column output format, don't print headers (default print headers).")//no-headers选项
    	cmd.Flags().StringP("output", "o", "", "Output format. One of: name")//output选项
    	return cmd
    }

//准备
    func (o *GetContextsOptions) Complete(cmd *cobra.Command, args []string) error {
    	o.contextNames = args//设置contextNames
    	o.nameOnly = false//设置nameOnly
    	if cmdutil.GetFlagString(cmd, "output") == "name" {//如果输出格式是name，设置nameOnly为true
    		o.nameOnly = true
    	}
    	o.showHeaders = true//设置showHeaders
    	if cmdutil.GetFlagBool(cmd, "no-headers") || o.nameOnly {//如果no-headers或nameOnly为true，设置shouHeaders为false
    		o.showHeaders = false
    	}
    
    	return nil
    }

//运行
    func (o GetContextsOptions) RunGetContexts() error {
    	config, err := o.configAccess.GetStartingConfig()//加载config
    	if err != nil {
    		return err
    	}
    
    	out, found := o.Out.(*tabwriter.Writer)//把out转为tabwriter
    	if !found {//转换失败
    		out = printers.GetNewTabWriter(o.Out)//包装tabwriter
    		defer out.Flush()
    	}
    
    	// Build a list of context names to print, and warn if any requested contexts are not found.
    	// Do this before printing the headers so it doesn't look ugly.
    	allErrs := []error{}
    	toPrint := []string{}
    	if len(o.contextNames) == 0 {//如果contextName为空
    		for name := range config.Contexts {//append所有contexts name到toPrint
    			toPrint = append(toPrint, name)
    		}
    	} else {
    		for _, name := range o.contextNames {//遍历contextNames
    			_, ok := config.Contexts[name]//判断context是否存在
    			if ok {//如果存在append到toPrint
    				toPrint = append(toPrint, name)
    			} else {//不存在append错误
    				allErrs = append(allErrs, fmt.Errorf("context %v not found", name))
    			}
    		}
    	}
    	if o.showHeaders {//如果showHeaders为true
    		err = printContextHeaders(out, o.nameOnly)// 打印头
    		if err != nil {
    			allErrs = append(allErrs, err)
    		}
    	}
    
    	sort.Strings(toPrint)//对context进行排序
    	for _, name := range toPrint {//遍历toPrint
    		err = printContext(name, config.Contexts[name], out, o.nameOnly, config.CurrentContext == name)//打印context
    		if err != nil {
    			allErrs = append(allErrs, err)
    		}
    	}
    
    	return utilerrors.NewAggregate(allErrs)
    }

//打印头
    func printContextHeaders(out io.Writer, nameOnly bool) error {
    	columnNames := []string{"CURRENT", "NAME", "CLUSTER", "AUTHINFO", "NAMESPACE"}
    	if nameOnly {//如果nameOnly取第一个
    		columnNames = columnNames[:1]
    	}
    	_, err := fmt.Fprintf(out, "%s\n", strings.Join(columnNames, "\t"))//打印头
    	return err
    }
    
    //打印context
    func printContext(name string, context *clientcmdapi.Context, w io.Writer, nameOnly, current bool) error {
    	if nameOnly {//如果nameOnly打印name返回
    		_, err := fmt.Fprintf(w, "%s\n", name)
    		return err
    	}
    	prefix := " "
    	if current {// 如果是当前context，打印*号
    		prefix = "*"
    	}
    	_, err := fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\n", prefix, name, context.Cluster, context.AuthInfo, context.Namespace)//打印context
    	return err
    }

[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAaHhwamF2YTE_size_8_color_FFFFFF_t_70_g_se_x_16]: https://img-blog.csdnimg.cn/20211007094240106.jpg?x-oss-process=image/watermark,type_ZHJvaWRzYW5zZmFsbGJhY2s,shadow_50,text_Q1NETiBAaHhwamF2YTE=,size_8,color_FFFFFF,t_70,g_se,x_16
[istio_50]: https://mp.weixin.qq.com/s/_OPMjmWCDSTlmbAxytg33A
[istio]: https://mp.weixin.qq.com/s/kjvtno_UzJAGr1joxm3tvw
[istio_istio]: https://mp.weixin.qq.com/s/e2-p_NY31Mc5y07S4Bb1JQ
[istio 1]: https://mp.weixin.qq.com/s/iTV0SCQLhSOTYncp3PxoHQ
[istio 2]: https://mp.weixin.qq.com/s/eINlrT242RlAwfuZu1_PcA
[envoyfilter_istio_-http-rbac-_AuthorizationPolicy]: https://mp.weixin.qq.com/s/Q-yTGBNqkjOov49LTXPrPA
[envoyfilter_istio_-02-http-corsFilter-_vs]: https://mp.weixin.qq.com/s/bFMdrT7OKSqoWv8pDXOIqQ
[envoyfilter_istio_-03-http-csrf filter-_csrf]: https://mp.weixin.qq.com/s/dlG9phV-kMMxs4UPzuRNYg
[envoyfilter_istio_http-jwt_authn-_RequestAuthorization]: https://mp.weixin.qq.com/s/IfrJ-FdLYsdhPkDrcO_YXA
[envoyfilter_istio_-05-fault-filter-_vs]: https://mp.weixin.qq.com/s/a4gDXqD8uswgglMwkUph2Q
[envoyfilter_istio_-06-http-match-_vs]: https://mp.weixin.qq.com/s/TpS3DHdcaJiPivIS_jsIGw
[envoyfilter_istio_-07-_dr]: https://mp.weixin.qq.com/s/k-zJm7n7OOKg6MotQJYPAA
[envoyfilter_istio_-08-]: https://mp.weixin.qq.com/s/n_bJ3saNeTtXRprIymhwzg
[envoyfilter_istio_-09-http-route filter]: https://mp.weixin.qq.com/s/JAeZr0BMVQxIrB3S_7Ru0A
[envoyfilter_istio_-network filter-redis proxy]: https://mp.weixin.qq.com/s/B9IPTI8F3q42nVkqbQRlPw
[envoyfilter_istio_-network filter-HttpConnectionManager]: https://mp.weixin.qq.com/s/W3OPQWkCVvuHGS49cTNhlg
[envoyfilter_istio_-ratelimit-istio ratelimit]: https://mp.weixin.qq.com/s/KgiDsELNol27mgZvDbFsqw