go - 启动Go HTTP服务器，执行某些操作，然后在完成任务后将其关闭

Question

我正在通过CLI应用程序设置OAuth2流。我需要为提供商创建一个临时HTTP服务器，以将回调发送至localhost:8080/callback提供程序发送完我需要的详细信息后，我希望能够关闭HTTP服务器，只是保持一切干净。我认为我正在寻找的是例程和 WaitGroup ，但是对于这个领域我还是很陌生。
这是我到目前为止所拥有的。我修改了将用户发送到提供程序的部分，因为我的主要问题只是捕获了token变量后如何关闭HTTP服务器。

服务器启动

将用户定向到提供程序站点

上的授权URL

用户批准请求

提供程序将用户引导回localhost:8080/callback

URL仅包含客户端参数，因此我必须使用HTML服务器才能使用JS捕获值并将其发送回服务器

服务器接收 token ，然后可以关闭

package main

import (
    "fmt"
    "log"
    "net/http"
    "sync"
)

func main() {
    // Start local HTTP serevr to listen for response
    serverDone := &sync.WaitGroup{}
    serverDone.Add(1)
    Start(serverDone)

    // ... Process to start OAuth2 flow
    // User is directed to provider website
    // User approves
    // Provider direct user back to localhost/callback
    
    serverDone.Wait()
}

func Start(wg *sync.WaitGroup) {

    srv := &http.Server{Addr: ":8080"}
    http.HandleFunc("/callback", func(w http.ResponseWriter, r *http.Request) {
        token := r.URL.Query().Get("token")
        if token != "" {
            fmt.Println("Found Token:", token)
            // Shut down server here
        } else {
            // Server HTML page to fetch token and return to server at /callback
        }
    })

    go func() {
        // let main know we are done cleaning up
        defer wg.Done()

        // ErrServerClosed on graceful close
        if err := srv.ListenAndServe(); err != http.ErrServerClosed {
            log.Fatalf("ListenAndServe(): %v", err)
        }
    }()
}

Answer 1

使用:

var ctxShutdown, cancel = context.WithCancel(context.Background())

然后:

cancel() // to say sorry, above.
// graceful-shutdown
err := srv.Shutdown(context.Background())

试试这个:

package main

import (
    "context"
    "fmt"
    "log"
    "net/http"
    "sync"
)

func main() {
    serverDone := &sync.WaitGroup{}
    serverDone.Add(1)
    Start(serverDone)
    serverDone.Wait()
    fmt.Println("Done that.")
}

var ctxShutdown, cancel = context.WithCancel(context.Background())

func Start(wg *sync.WaitGroup) {
    srv := &http.Server{Addr: ":8080"}
    http.HandleFunc("/callback", func(w http.ResponseWriter, r *http.Request) {
        select {
        case <-ctxShutdown.Done():
            fmt.Println("Sorry: Shuting down ...")
            return
        default:
        }
        token := r.URL.Query().Get("token")
        if token != "" {
            fmt.Println("Found Token:", token)
            fmt.Println("Shuting down ...")
            // Shut down server here
            cancel() // to say sorry, above.
            // graceful-shutdown
            err := srv.Shutdown(context.Background())
            if err != nil {
                log.Println("server.Shutdown:", err)
            }

        } else {
            fmt.Fprintln(w, "Hi") // Server HTML page to fetch token and return to server at /callback
        }
    })

    go func() {
        defer wg.Done()
        if err := srv.ListenAndServe(); err != http.ErrServerClosed {
            log.Fatalf("ListenAndServe(): %v", err)
        }
        fmt.Println("Bye.")
    }()
}

运行并打开 http://127.0.0.1:8080/callback?token=2
输出:

Found Token: 2
Shuting down ...
Bye.
Done that.