全球微头条丨【prometheus】-04 轻松搞定Prometheus Eureka服务发现

2023-03-26 17:18:30 来源:腾讯云

Prometheus服务发现机制之Eureka

概述

Eureka服务发现协议允许使用Eureka Rest API检索出Prometheus需要监控的targets,Prometheus会定时周期性的从Eureka调用Eureka Rest API,并将每个应用实例创建出一个target。


(资料图)

Eureka服务发现协议支持对如下元标签进行relabeling

__meta_eureka_app_name: the name of the app__meta_eureka_app_instance_id: the ID of the app instance__meta_eureka_app_instance_hostname: the hostname of the instance__meta_eureka_app_instance_homepage_url: the homepage url of the app instance__meta_eureka_app_instance_statuspage_url: the status page url of the app instance__meta_eureka_app_instance_healthcheck_url: the health check url of the app instance__meta_eureka_app_instance_ip_addr: the IP address of the app instance__meta_eureka_app_instance_vip_address: the VIP address of the app instance__meta_eureka_app_instance_secure_vip_address: the secure VIP address of the app instance__meta_eureka_app_instance_status: the status of the app instance__meta_eureka_app_instance_port: the port of the app instance__meta_eureka_app_instance_port_enabled: the port enabled of the app instance__meta_eureka_app_instance_secure_port: the secure port address of the app instance__meta_eureka_app_instance_secure_port_enabled: the secure port of the app instance__meta_eureka_app_instance_country_id: the country ID of the app instance__meta_eureka_app_instance_metadata_: app instance metadata__meta_eureka_app_instance_datacenterinfo_name: the datacenter name of the app instance__meta_eureka_app_instance_datacenterinfo_: the datacenter metadata

eureka_sd_configs配置可选项如下:

# The URL to connect to the Eureka server.server: # Sets the `Authorization` header on every request with the# configured username and password.# password and password_file are mutually exclusive.basic_auth:  [ username:  ]  [ password:  ]  [ password_file:  ]# Optional `Authorization` header configuration.authorization:  # Sets the authentication type.  [ type:  | default: Bearer ]  # Sets the credentials. It is mutually exclusive with  # `credentials_file`.  [ credentials:  ]  # Sets the credentials to the credentials read from the configured file.  # It is mutually exclusive with `credentials`.  [ credentials_file:  ]# Optional OAuth 2.0 configuration.# Cannot be used at the same time as basic_auth or authorization.oauth2:  [  ]# Configures the scrape request"s TLS settings.tls_config:  [  ]# Optional proxy URL.[ proxy_url:  ]# Configure whether HTTP requests follow HTTP 3xx redirects.[ follow_redirects:  | default = true ]# Refresh interval to re-read the app instance list.[ refresh_interval:  | default = 30s ]

协议分析

通过前面分析的Prometheus服务发现原理以及基于文件方式服务发现协议实现的分析,Eureka服务发现大致原理如下图:

通过解析配置中eureka_sd_configs协议的job生成Config,然后NewDiscovery方法创建出对应的Discoverer,最后调用Discoverer.Run()方法启动服务发现targets。

1、基于文件服务发现配置解析

假如我们定义如下job:

- job_name: "eureka"  eureka_sd_configs:    - server: http://localhost:8761/eureka    

会被解析成eureka.SDConfig如下:

eureka.SDConfig定义如下:

type SDConfig struct {    // eureka-server地址 Server           string                  `yaml:"server,omitempty"`    // http请求client配置,如:认证信息 HTTPClientConfig config.HTTPClientConfig `yaml:",inline"`    // 周期刷新间隔,默认30s RefreshInterval  model.Duration          `yaml:"refresh_interval,omitempty"`}

2、Discovery创建

func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) { rt, err := config.NewRoundTripperFromConfig(conf.HTTPClientConfig, "eureka_sd", config.WithHTTP2Disabled()) if err != nil {  return nil, err } d := &Discovery{  client: &http.Client{Transport: rt},  server: conf.Server, } d.Discovery = refresh.NewDiscovery(  logger,  "eureka",  time.Duration(conf.RefreshInterval),  d.refresh, ) return d, nil}

3、Discovery创建完成,最后会调用Discovery.Run()启动服务发现:

和上一节分析的服务发现之File机制类似,执行Run方法时会执行tgs, err := d.refresh(ctx),然后创建定时周期触发器,不停执行tgs, err := d.refresh(ctx),将返回的targets结果信息通过channel传递出去。

4、上面Run方法核心是调用d.refresh(ctx)逻辑获取targets,基于Eureka发现协议主要实现逻辑就在这里:

func (d *Discovery) refresh(ctx context.Context) ([]*targetgroup.Group, error) { // 通过Eureka REST API接口从eureka拉取元数据:http://ip:port/eureka/apps apps, err := fetchApps(ctx, d.server, d.client) if err != nil {  return nil, err } tg := &targetgroup.Group{  Source: "eureka", } for _, app := range apps.Applications {//遍历app        // targetsForApp()方法将app下每个instance部分转成target  targets := targetsForApp(&app)        //假如到  tg.Targets = append(tg.Targets, targets...) } return []*targetgroup.Group{tg}, nil}

refresh方法主要有两个流程:

1、fetchApps():从eureka-server/eureka/apps接口拉取注册服务信息;

2、targetsForApp():遍历appinstance,将每个instance解析出一个target,并添加一堆元标签数据。

如下就是从eureka-server的/eureka/apps接口拉取的注册服务信息:

    1    UP_1_            SERVICE-PROVIDER-01                    localhost:service-provider-01:8001            192.168.3.121            SERVICE-PROVIDER-01            192.168.3.121            UP            UNKNOWN            8001            443            1                            MyOwn                                        30                90                1629385562130                1629385682050                0                1629385562132                                        8001                true                8080                        http://192.168.3.121:8001/            http://192.168.3.121:8001/actuator/info            http://192.168.3.121:8001/actuator/health            service-provider-01            service-provider-01            false            1629385562132            1629385562039            ADDED            

5、instance信息解析target

func targetsForApp(app *Application) []model.LabelSet { targets := make([]model.LabelSet, 0, len(app.Instances)) // Gather info about the app"s "instances". Each instance is considered a task. for _, t := range app.Instances {  var targetAddress string        // __address__取值方式:instance.hostname和port,没有port则默认port=80  if t.Port != nil {   targetAddress = net.JoinHostPort(t.HostName, strconv.Itoa(t.Port.Port))  } else {   targetAddress = net.JoinHostPort(t.HostName, "80")  }  target := model.LabelSet{   model.AddressLabel:  lv(targetAddress),   model.InstanceLabel: lv(t.InstanceID),   appNameLabel:                     lv(app.Name),   appInstanceHostNameLabel:         lv(t.HostName),   appInstanceHomePageURLLabel:      lv(t.HomePageURL),   appInstanceStatusPageURLLabel:    lv(t.StatusPageURL),   appInstanceHealthCheckURLLabel:   lv(t.HealthCheckURL),   appInstanceIPAddrLabel:           lv(t.IPAddr),   appInstanceVipAddressLabel:       lv(t.VipAddress),   appInstanceSecureVipAddressLabel: lv(t.SecureVipAddress),   appInstanceStatusLabel:           lv(t.Status),   appInstanceCountryIDLabel:        lv(strconv.Itoa(t.CountryID)),   appInstanceIDLabel:               lv(t.InstanceID),  }  if t.Port != nil {   target[appInstancePortLabel] = lv(strconv.Itoa(t.Port.Port))   target[appInstancePortEnabledLabel] = lv(strconv.FormatBool(t.Port.Enabled))  }  if t.SecurePort != nil {   target[appInstanceSecurePortLabel] = lv(strconv.Itoa(t.SecurePort.Port))   target[appInstanceSecurePortEnabledLabel] = lv(strconv.FormatBool(t.SecurePort.Enabled))  }  if t.DataCenterInfo != nil {   target[appInstanceDataCenterInfoNameLabel] = lv(t.DataCenterInfo.Name)   if t.DataCenterInfo.Metadata != nil {    for _, m := range t.DataCenterInfo.Metadata.Items {     ln := strutil.SanitizeLabelName(m.XMLName.Local)     target[model.LabelName(appInstanceDataCenterInfoMetadataPrefix+ln)] = lv(m.Content)    }   }  }  if t.Metadata != nil {   for _, m := range t.Metadata.Items {                // prometheus label只支持[^a-zA-Z0-9_]字符,其它非法字符都会被替换成下划线_    ln := strutil.SanitizeLabelName(m.XMLName.Local)    target[model.LabelName(appInstanceMetadataPrefix+ln)] = lv(m.Content)   }  }  targets = append(targets, target) } return targets}

解析比较简单,就不再分析,解析后的标签数据如下图:

标签中有两个特别说明下:

1、__address__:这个取值instance.hostname和port(默认80),所以要注意注册到eureka上的hostname准确性,不然可能无法抓取;

2、metadata-map数据会被转成__meta_eureka_app_instance_metadata_格式标签,prometheus进行relabeling一般操作metadata-map,可以自定义metric_path、抓取端口等;

3、prometheuslabel只支持[a-zA-Z0-9_],其它非法字符都会被转换成下划线,具体参加:strutil.SanitizeLabelName(m.XMLName.Local);但是eureka的metadata-map标签含有下划线时,注册到eureka-server上变成双下划线,如下配置:

eureka:  instance:    metadata-map:      scrape_enable: true      scrape.port: 8080

通过/eureka/apps获取如下:

总结

基于Eureka方式的服务原理如下图:

大概说明:Discoverer启动后定时周期触发从eureka server/eureka/apps接口拉取注册服务元数据,然后通过targetsForApp遍历app下的instance,将每个instance解析成target,并将其它元数据信息转换成target原标签可以用于target抓取前relabeling操作。

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