全球微头条丨【prometheus】-04 轻松搞定Prometheus Eureka服务发现
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 metadataeureka_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
的/eureka/apps
接口拉取注册服务信息;
2、targetsForApp()
:遍历app
下instance
,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、prometheus
的label
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
的/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。
标签:
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