Tracing HTTP - Baggage

baggage Link Data Transmission

baggage transmits custom information between links (between services).

Example code address: https://github.com/gogf/gf/tree/master/example/trace/http

Client

package main

import (
    "github.com/gogf/gf/contrib/trace/otlphttp/v2"
    "github.com/gogf/gf/v2/frame/g"
    "github.com/gogf/gf/v2/net/gtrace"
    "github.com/gogf/gf/v2/os/gctx"
)

const (
     serviceName = "otlp-http-client"
    endpoint    = "tracing-analysis-dc-hz.aliyuncs.com"
    path        = "adapt_******_******/api/otlp/traces"
)

func main() {
    var ctx = gctx.New()
    shutdown, err := otlphttp.Init(serviceName, endpoint, path)
   if err != nil {
        g.Log().Fatal(ctx, err)
    }
    defer shutdown()

    StartRequests()
}

func StartRequests() {
    ctx, span := gtrace.NewSpan(gctx.New(), "StartRequests")
    defer span.End()

    ctx = gtrace.SetBaggageValue(ctx, "name", "john")

    content := g.Client().GetContent(ctx, "http://127.0.0.1:8199/hello")
    g.Log().Print(ctx, content)
}

Brief explanation of client code:

1. First, the client also needs to initialize Jaeger through the jaeger.Init method.
2. Then, using gtrace.SetBaggageValue(ctx, "name", "john"), a baggage is set, which will be transmitted in all links of the request. However, in this example, there are only two nodes, so the baggage data will only be transmitted to the server. This method will return a new context.Context variable, which we will need to pass in the subsequent call chain.
3. Here, an HTTP client request object is created using g.Client(), which automatically enables tracing features without requiring developers to explicitly call any methods or settings.
4. Finally, g.Log().Print(ctx, content) is used to print the server‘s return content, where ctx is used to pass link information to the logging component. If the ctx context object contains link information, the logging component will automatically include the TraceId in the log content.

Server

package main

import (
    "github.com/gogf/gf/contrib/trace/otlphttp/v2"
    "github.com/gogf/gf/v2/frame/g"
    "github.com/gogf/gf/v2/net/ghttp"
    "github.com/gogf/gf/v2/net/gtrace"
    "github.com/gogf/gf/v2/os/gctx"
)

const (
     serviceName = "otlp-http-server"
    endpoint    = "tracing-analysis-dc-hz.aliyuncs.com"
    path        = "adapt_******_******/api/otlp/traces" )

func main() {
    var ctx = gctx.New()
    shutdown, err := otlphttp.Init(serviceName, endpoint, path)
    if err != nil {
        g.Log().Fatal(ctx, err)
    }
    defer shutdown()

    s := g.Server()
    s.Group("/", func(group *ghttp.RouterGroup) {
        group.GET("/hello", HelloHandler)
    })
    s.SetPort(8199)
    s.Run()
}

func HelloHandler(r *ghttp.Request) {
    ctx, span := gtrace.NewSpan(r.Context(), "HelloHandler")
    defer span.End()

    value := gtrace.GetBaggageVar(ctx, "name").String()

    r.Response.Write("hello:", value)
}

Brief explanation of server code:

1. Of course, the server also needs to initialize Jaeger through the jaeger.Init method.
2. The server starts with tracing enabled, and developers do not need to call any methods or configure any settings explicitly.
3. The server uses gtrace.GetBaggageVar(ctx, "name").String() to obtain the baggage information submitted by the client and converts it to a string for return.

View the Effects

Start the server:

Start the client:

As you can see, the baggage submitted by the client has been successfully received and printed by the server. Also, the client outputs the TraceId information when logging. TraceId is a unique ID for a link, and it can be used to retrieve all log information for that link as well as query the detailed call chain on the Jaeger system.

View the link information on Jaeger:

As seen here, there are two service names: tracing-http-client and tracing-http-server, indicating that this request involves two services, specifically the HTTP request client and server, and each service involves 2 span link nodes.

When clicking on the details of this trace, you can see the hierarchical relationship of the call chain. Additionally, you can find the client‘s request address, the server’s received route, and the server route function names. Let’s introduce the Attributes and Events information of the client, or the Tags and Process information shown in Jaeger.

HTTP Client Attributes

HTTP Client Events

HTTP Server Attributes

The Attributes of the HTTP Server side are the same as those of the HTTP Client, and similar data is printed in the same request.

HTTP Server Events

The Events of the HTTP Server side are the same as those of the HTTP Client, and similar data is printed in the same request.