gonic反向代理导致恐慌“接口转换：*http.timeoutWriter is http.CloseNotifier:缺失方法CloseNotify”
gonic反向代理导致恐慌“接口转换：*http.timeoutWriter is http.CloseNotifier:缺失方法CloseNotify”
提问于 2017-04-28 02:15:50
我正在使用金刚框架创建一个反向代理端点，使用下面给出的代码使用grpc网关来服务目标端点。这类似于为gin 这里和这里建议的反向代理方法。
ep1 := v1.Group("/ep1")
{
ep1.GET("/ep2", reverseProxy("http://localhost:50000"))
}
func reverseProxy(target string) gin.HandlerFunc {
url, err := url.Parse(target)
if err != nil {
log.Println("Reverse Proxy target url could not be parsed:", err)
return nil
}
proxy := httputil.NewSingleHostReverseProxy(url)
return func(c *gin.Context) {
proxy.ServeHTTP(c.Writer, c.Request)
}
}但是，当实际向这个gin端点(/ep1/ep2)发送请求时，会看到go恐慌：
interface conversion: *http.timeoutWriter is not http.CloseNotifier: missing method CloseNotify
/usr/local/Cellar/go/1.8/libexec/src/runtime/panic.go:489 (0x10288df)
gopanic: reflectcall(nil, unsafe.Pointer(d.fn), deferArgs(d), uint32(d.siz), uint32(d.siz))
/usr/local/Cellar/go/1.8/libexec/src/runtime/iface.go:131 (0x100c3af)
additab: panic(&TypeAssertionError{"", typ.string(), inter.typ.string(), iname})
/usr/local/Cellar/go/1.8/libexec/src/runtime/iface.go:79 (0x100bc34)
getitab: additab(m, true, canfail)
/usr/local/Cellar/go/1.8/libexec/src/runtime/iface.go:256 (0x100cbb8)
assertI2I: r.tab = getitab(inter, tab._type, false)
/path/to/vendor/github.com/gin-gonic/gin/response_writer.go:110 (0x14de6f3)
(*responseWriter).CloseNotify: return w.ResponseWriter.(http.CloseNotifier).CloseNotify()
/usr/local/Cellar/go/1.8/libexec/src/net/http/httputil/reverseproxy.go:142 (0x14d4d12)
(*ReverseProxy).ServeHTTP: notifyChan := cn.CloseNotify()
/path/to/main.go:379 (0x16d2ead)
reverseProxy.func1: proxy.ServeHTTP(c.Writer, c.Request)
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/locale.go:12 (0x15737d9)
getLocaleMiddleware.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/session_cookie.go:27 (0x1574e7c)
getSessionCookieMiddleware.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/affiliate_api.go:27 (0x15729a1)
getAffiliateAPIMiddleware.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/metrics.go:17 (0x157465b)
getMetricsMiddleware.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/input_validations.go:75 (0x1572dcb)
getInputValidationMiddleware.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/logger.go:68 (0x1573aea)
LoggerWithWriter.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/middlewares/request_tracer.go:13 (0x1574d6c)
getTracerContext.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/vendor/github.com/gin-gonic/gin/recovery.go:45 (0x14e4b6a)
RecoveryWithWriter.func1: c.Next()
/path/to/vendor/github.com/gin-gonic/gin/context.go:97 (0x14d657a)
(*Context).Next: c.handlers[c.index](c)
/path/to/vendor/github.com/gin-gonic/gin/gin.go:284 (0x14dc710)
(*Engine).handleHTTPRequest: context.Next()
/path/to/vendor/github.com/gin-gonic/gin/gin.go:265 (0x14dc02b)
(*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/usr/local/Cellar/go/1.8/libexec/src/net/http/server.go:2967 (0x140fa53)
(*timeoutHandler).ServeHTTP.func1: h.handler.ServeHTTP(tw, r)
/usr/local/Cellar/go/1.8/libexec/src/runtime/asm_amd64.s:2197 (0x1054851)对于为什么会发生这种情况，或者代码中有什么问题，有什么想法吗？
回答 1
Stack Overflow用户
回答已采纳
发布于 2017-05-10 09:52:35
发现这个问题是因为代码库没有直接使用来自gin-gonic的gin-gonic方法。相反，它在启动http服务器时使用了超时，如下所示(这里使用了部分相关代码)：
type H struct {
sync.Mutex
Engine *gin.Engine
listener net.Listener
running bool
}
.
.
.
var h H
s := &http.Server{
Addr: address,
Handler: http.TimeoutHandler(h.Engine, time.Duration(100000)*time.Millisecond, ""),
ReadTimeout: time.Duration(100000) * time.Millisecond,
WriteTimeout: time.Duration(100000) * time.Millisecond,
}
h.listener, err := net.Listen("tcp", s.Addr)
if err != nil {
return err
}
h.running = true
s.Serve(h.listener)但是，http.TimeoutHandler并没有像在http://grokbase.com/t/gg/golang-dev/13796p5h1n/net-http-timeouthandler-vs-closenotify中提到的那样实现http.CloseNotifer接口--这导致了一个带有错误消息interface conversion: *http.timeoutWriter is not http.CloseNotifier: missing method CloseNotify的panic
因此，作为解决此问题的方法，在使用ReadTimeout和WriteTimeout值http.Server用于超时时，服务器处理程序被修改为直接作为gin引擎。
修改后的代码不再恐慌，并导致成功的反向代理：
type H struct {
sync.Mutex
Engine *gin.Engine
listener net.Listener
running bool
}
.
.
.
var h H
s := &http.Server{
Addr: address,
Handler: h.Engine,
ReadTimeout: time.Duration(100000) * time.Millisecond,
WriteTimeout: time.Duration(100000) * time.Millisecond,
}
h.listener, err := net.Listen("tcp", s.Addr)
if err != nil {
return err
}
h.running = true
s.Serve(h.listener)注意，这里只需要修改Handler for &http.Server。此外，不需要从问题中修改原始的反向代理代码。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/43670872
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