When the HTTP client sends a request, it can customize the Header content sent to the server, a feature implemented using the SetHeader* related methods.

Method List:

func (c *Client) SetHeader(key, value string) *Client
func (c *Client) SetHeaderMap(m map[string]string) *Client
func (c *Client) SetHeaderRaw(headers string) *Client

Let’s take a look at an example where the client customizes the sending of custom tracing information Span-Id and Trace-Id message headers using Header.

Server

package main
import (
    "github.com/gogf/gf/v2/frame/g"
    "github.com/gogf/gf/v2/net/ghttp"
)
func main() {
    s := g.Server()
    s.BindHandler("/", func(r *ghttp.Request) {
        r.Response.Writef(
            "Span-Id:%s,Trace-Id:%s",
            r.Header.Get("Span-Id"),
            r.Header.Get("Trace-Id"),
        )
    })
    s.SetPort(8199)
    s.Run()
}

Since this is an example, the server logic is straightforward, directly returning the received Span-Id and Trace-Id parameters to the client.

Client

1. Using the SetHeader Method

package main
import (
       "fmt"
       "github.com/gogf/gf/v2/frame/g"
       "github.com/gogf/gf/v2/os/gctx"
)
func main() {
       c := g.Client()
       c.SetHeader("Span-Id", "0.0.1")
       c.SetHeader("Trace-Id", "NBC56410N97LJ016FQA")
       if r, e := c.Get(gctx.New(), "http://127.0.0.1:8199/"); e != nil {
           panic(e)
       } else {
           fmt.Println(r.ReadAllString())
       }
}

Create a custom HTTP request client object using g.Client() and set custom Header information using c.SetHeader.

1. Using the SetHeaderRaw Method

This method is simpler and allows setting the client request Header via a raw Header string.

package main
import (
       "fmt"
       "github.com/gogf/gf/v2/frame/g"
       "github.com/gogf/gf/v2/os/gctx"
)
func main() {
       c := g.Client()
       c.SetHeaderRaw(`
           Referer: https://localhost
           Span-Id: 0.0.1
           Trace-Id: NBC56410N97LJ016FQA
           User-Agent: MyTestClient
       `)
       if r, e := c.Get(gctx.New(), "http://127.0.0.1:8199/"); e != nil {
           panic(e)
       } else {
           fmt.Println(r.ReadAllString())
       }
}

1. Execution Result

After executing the client code, the terminal will print the result returned by the server, as follows:

Span-Id:0.0.1,Trace-Id:NBC56410N97LJ016FQA