背景

所在專案Go服務之前部署在測試機器上，最近再把Go的配置遷移到etcd，但是因為etcd沒有對應的測試環境，而公司裡面網段是隔離的，導致了原本的Go服務再接入etcd之後跑不起來。

• 讓Go服務正常啟動，
• 其他依賴方，比如前端、閘道器少做修改

方案

Go服務部署到docker上，docker上的域名都是特定字尾結尾，這樣會涉及到cookie等一些問題，所以考慮通過測試機的Nginx做代理。

問題

• http 426 報錯：測試環境的http協議是1.0，而docker上的http協議是1.1，所以需要在nginx轉發的時候，新增header頭。如果是websocket可以參考下
  https://www.nginx.com/blog/websocket-nginx/
• http 404 報錯：Nginx在做轉發的時候，需要加上host header頭，域名解析找到對應的主機，但是需要根據host資訊，找到對應的服務。

插曲

再解決問題的時候，通過curl -I 在訪問docker上的服務，一直提示404，但是通過curl直接訪問的時候，正常。後來想到curl -I是通過head的方式請求。專案註冊的路由請求方式是get，但是Iris的底層路由，404和405報錯不能共存，iris預設會將404和405報錯統一的轉換成404報錯。
直接上程式碼

pool.Run(w, r, func
 
(context *iris.Context) {
            routePath := context.Path()
            for i := range mux.garden {
                tree := mux.garden[i]
                if !mux.methodEqual(context.Request.Method, tree.method) {
                    continue
                }

                if mux.hosts && tree.subdomain != ""
 
 {

                    requestHost := context.Host()
                    // println("mux are true and tree.subdomain= " + tree.subdomain + "and hostname = " + hostname + " host = " + requestHost)
                    if requestHost != hostname {
                        // we have a subdomain
                        if strings.Contains(tree.subdomain, iris.DynamicSubdomainIndicator) {
                        } else {
                            if tree.subdomain+hostname != requestHost {
                                // go to the next tree, we have a subdomain but it is not the correct
                                continue
                            }
                        }
                    } else {
                        //("it's subdomain but the request is not the same as the vhost)
                        continue
                    }
                }

                mustRedirect := tree.entry.getValue(routePath, context) // pass the parameters here for 0 allocation
                if context.Middleware != nil {
                    // ok we found the correct route, serve it and exit entirely from here
                    //ctx.Request.Header.SetUserAgentBytes(DefaultUserAgent)
                    context.Do()
                    return
                } else if mustRedirect && !context.Framework().Config.DisablePathCorrection { // && context.Method() == MethodConnect {
                    reqPath := routePath
                    pathLen := len(reqPath)

                    if pathLen > 1 {
                        if reqPath[pathLen-1] == '/' {
                            reqPath = reqPath[:pathLen-1] //remove the last /
                        } else {
                            //it has path prefix, it doesn't ends with / and it hasn't be found, then just add the slash
                            reqPath = reqPath + "/"
                        }

                        urlToRedirect := reqPath

                        statusForRedirect := iris.StatusMovedPermanently // StatusMovedPermanently, this document is obselte, clients caches this.
                        if tree.method == iris.MethodPost ||
                            tree.method == iris.MethodPut ||
                            tree.method == iris.MethodDelete {
                            statusForRedirect = iris.StatusTemporaryRedirect // To maintain POST data
                        }

                        context.Redirect(urlToRedirect, statusForRedirect)
                        // RFC2616 recommends that a short note "SHOULD" be included in the
                        // response because older user agents may not understand 301/307.
                        // Shouldn't send the response for POST or HEAD; that leaves GET.
                        if tree.method == iris.MethodGet {
                            note := "<a href=\"" + HTMLEscape(urlToRedirect) + "\">Moved Permanently</a>.\n"
                            // ignore error
                            context.WriteString(note)
                        }
                        return
                    }
                }
                // not found
                break
            }
            // https://github.com/kataras/iris/issues/469
            if context.Framework().Config.FireMethodNotAllowed {
                var methodAllowed string
                for i := range mux.garden {
                    tree := mux.garden[i]
                    methodAllowed = tree.method // keep track of the allowed method of the last checked tree
                    if !mux.methodEqual(context.Method(), tree.method) {
                        continue
                    }
                }
                // RCF rfc2616 https://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html
                // The response MUST include an Allow header containing a list of valid methods for the requested resource.
                context.SetHeader("Allow", methodAllowed)
                context.EmitError(iris.StatusMethodNotAllowed)
                return
            }
            context.EmitError(iris.StatusNotFound)
        })