agent

README

Jaeger Agent

jaeger-agent is a daemon program that runs on every host and receives tracing information submitted by applications via Jaeger client libraries.

Structure

• Agent
  • processor as ThriftProcessor
    • server as TBufferedServer
      • Thrift UDP Transport
    • reporter as TCollectorReporter
  • sampling server
    • sampling manager as sampling.TCollectorProxy

UDP Server

Listens on UDP transport, reads data as []byte and forwards to processor over channel. Processor has N workers that read from the channel, convert to thrift-generated object model, and pass on to the Reporter. TCollectorReporter submits the spans to remote tcollector service.

Sampling Server

An HTTP server handling request in the form

http://localhost:port/sampling?service=xxxx`

Delegates to sampling.Manager to get the sampling strategy. sampling.TCollectorProxy implements sampling.Manager by querying remote tcollector service. Then the server converts thrift response from sampling manager into JSON and responds to clients.

目录说明

1. httpserver: 作为agent server，用于给该agent所在的host上的微服务，提供获取采样策略、Baggage携带信息字段服务

• manager.go 提供服务接口声明(采样策略服务，Baggage携带信息字段列表)
• collector_proxy.go 作为agent client，微服务通过这个client获取这两个服务
• server.go 作为agent server的实现, 采样策略提供了两种：一、采样；二、流控

1. agent.go: 提供获取Agent实例，并通过Run方法运行多个worker processes和http server， 前者用于接收client的udp trace包，并作为生产者把trace包发送到channel队列上，然后多个worker processes通过竞争从这个channel队列上获取trace包，并push到collector server

2. builder.go: 提供用于agent需要的相关参数，包括worker processes参数、http server相关参数、collector server peers服务发现等, 并创建各个实例, 并把相关参数值设置到Builder实例中

3. flags.go: 设置默认的worker processes相关参数值, http server相关参数, Collector server相关参数