[DAY17]動手做個http服務吧~~

第 12 屆 iThome 鐵人賽

DAY 17

DevOps

欸你這週GO了嘛系列第 17 篇

12th鐵人賽

熱血奶爸v0.0.1

團隊神龍特攻隊-為了燒肉不小心成為一條龍

2020-09-25 08:39:21

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http服務基於client與server二個端點的交互行為，client發出request，server收下request後進行對應邏輯處理，最後返回一個response給client

最基本的處理流程可以用下圖來表示

可以看到request進來，會經過router，根據對應的path對到相對應的handler，最後response出去。

以下我們來實作一個http server

net/http golang原生套件

package main

import (
	"encoding/json"
	"log"	
	"net/http"
)

func ping(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(http.StatusOK)
	w.Header().Set("Content-Type", "application/json;charset=utf-8")
	//fmt.Fprintf(w, "pong")
	qq := map[string]string{
		"data": "pong",
	}
	json.NewEncoder(w).Encode(qq)
}
func mdfk(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(http.StatusOK)
	w.Header().Set("Content-Type", "application/json;charset=utf-8")
	//fmt.Fprintf(w, "pong")
	qq := map[string]string{
		"year":    "2020",
		"message": "mdfk",
	}
	json.NewEncoder(w).Encode(qq)
}

func main() {
	//設定訪問的路由，HandleFunc接受2個參數，第一個是路由地址，第二個為處理方式。
	//ex:如果打127.0.0.1:8787/ 這個url時，會進入"/" 對應的hanlder "ping"
	//打127.0.0.1:8787/2020，會進入"/2020" 對應的hanlder "mdfk"

	http.HandleFunc("/", ping)
	http.HandleFunc("/2020", mdfk)
	err := http.ListenAndServe(":8787", nil) //設定監聽的埠
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}

直接呼叫127.0.0.1:8787/2020看看否成功

curl --location --request GET '127.0.0.1:8787/2020'

有回傳值，表示server有收到request並回傳respose

{"message":"mdfk","year":"2020"}

除了上面的最基礎的寫法外，還可以自定義server的設定值

func main() {
	mux := http.NewServeMux()
	mux.HandleFunc("/", ping)
	mux.HandleFunc("/bye", mdfk)

	//定義一個http.Server struct
	server := &http.Server{
		//Addr填入host:port，如果是localhost就直接填入:port就好
		Addr: ":8787",
		//timeout設定
		WriteTimeout: time.Second * 3,
		ReadTimeout:  time.Second * 30,
		//ServeMux
		Handler: mux,
	}
	log.Println("go http srever")
	log.Fatal(server.ListenAndServe())
}

原生套件實作http server相對簡單，但是還是有一些不支援的功能
1.無法使用/customer/:customer_id
2.無法限制method(GET,POST,PUT,DELETE)
3.無法使用正則式

以下是除了原生套件外，星星數來說相對多的套件

gorilla/mux

github路徑：mux

與原生套件寫法87分像的寫法

只要把http.NewServeMux()換成mux.NewRouter()就好，handler都不用重構

package main

import (
	"encoding/json"
	"net/http"

	"github.com/gorilla/mux"
)

func main() {
	//net/http原生寫法
	//mux := http.NewServeMux()
	//改呼叫mux.NewRouter，其他寫法跟原生的基本上一樣
	mux := mux.NewRouter()
	//普通路由
	mux.HandleFunc("/", ping)
	mux.HandleFunc("/2020", mdfk)

	http.ListenAndServe(":8080", mux)
}

func ping(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(http.StatusOK)
	w.Header().Set("Content-Type", "application/json;charset=utf-8")
	//fmt.Fprintf(w, "pong")
	qq := map[string]string{
		"data": "pong",
	}
	json.NewEncoder(w).Encode(qq)
}
func mdfk(w http.ResponseWriter, r *http.Request) {

	w.WriteHeader(http.StatusOK)
	w.Header().Set("Content-Type", "application/json;charset=utf-8")
	//fmt.Fprintf(w, "pong")
	qq := map[string]string{
		"year":    "2020",
		"message": "mdfk",
	}
	json.NewEncoder(w).Encode(qq)
}

參數路曲

下面以path、query string跟正則match路徑，加上限制method為例

package main

import (
	"fmt"
	"net/http"

	"github.com/gorilla/mux"
)

func main() {
	mux := mux.NewRouter()
	//query string，限制使用post跟options
	mux.HandleFunc("/list", queryStringGetList).Methods(http.MethodPost, http.MethodOptions)
	//path parameter，限制使用get跟options
	mux.HandleFunc("/list2/{id}/{level}", pathGetList).Methods(http.MethodGet, http.MethodOptions)
	//正則路由parameter，id限制要輸入英文
	mux.HandleFunc("/list3/{id:[a-z]+}", regexGetList)
	http.ListenAndServe(":8080", mux)
}

func queryStringGetList(w http.ResponseWriter, r *http.Request) {
	v := r.URL.Query()
	id := v.Get("id")
	level := v.Get("level")
	fmt.Fprintln(w, "id: ", id, "level: ", level)
}
func pathGetList(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	level := vars["level"]
	fmt.Fprintln(w, "id: ", id, "level: ", level)
}
func regexGetList(w http.ResponseWriter, r *http.Request) {
	vars := mux.Vars(r)
	id := vars["id"]
	fmt.Fprintln(w, "id: ", id)
}

執行結果

//HTTP/1.1 405 Method Not Allowed，因為原本handler是限制使用post才行，所以確認有被限制住
curl '127.0.0.1:8080/list' -v

//HTTP/1.1 200 OK
curl --location --request POST '127.0.0.1:8080/list'

//使用path parameter，所以回傳值得到了id:  aaa level:  3
curl --location --request GET '127.0.0.1:8080/list2/aaa/3'

//使用限制path字串，正則限制path要為英文，所以此path不合法，會得到404 page not found
curl --location --request GET '127.0.0.1:8080/list3/aaa44445'

//符合正則，得到回傳id:  aaabbb
curl --location --request GET '127.0.0.1:8080/list3/aaabbb'

前綴路由與子路由

這功能很方便，如果需要不同路配搭不同middleware時，可以使用前綴來切割成多個子路由

package main

import (
	"fmt"
	"net/http"

	"github.com/gorilla/mux"
)

func main() {
	mux := mux.NewRouter()
	//設定前綴"/products/"並設成子路由
	products := mux.PathPrefix("/products/").Subrouter()
	products.HandleFunc("/list", queryStringGetList).Methods(http.MethodGet, http.MethodOptions)
	//設定前綴"/customer/"並設成子路由
	customer := mux.PathPrefix("/customer/").Subrouter()
	customer.HandleFunc("/list", queryStringGetList).Methods(http.MethodGet, http.MethodOptions)
	http.ListenAndServe(":8080", mux)
}

func queryStringGetList(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintln(w, "URL PATH:", r.URL.Path)
}

執行結果

//得到回傳值，URL PATH: /customer/list，與原本設定的子路由一致
curl --location --request GET '127.0.0.1:8080/customer/list'

//得到回傳值，URL PATH: /products/list，與原本設定的子路由一致
curl --location --request GET '127.0.0.1:8080/products/list'

middleware

middleware的詳細文章可以參考這篇 [鐵人賽Day04] - 淺談Middleware，簡單說事件介於request與response間，這樣子就不用每個handler都要寫相同的code(ex，log或是驗證權限)

範例使用剛剛的子路由設定，進行不同子路middleware的情境

package main

import (
	"fmt"
	"net/http"

	"github.com/gorilla/mux"
)

func main() {
	mux := mux.NewRouter()
	//設定前綴"/products/"並設成子路由
	products := mux.PathPrefix("/products/").Subrouter()
	products.HandleFunc("/list", queryStringGetList).Methods(http.MethodGet, http.MethodOptions)
	//products 子路由使用loggingMiddleware
	products.Use(loggingMiddleware)

	//設定前綴"/customer/"並設成子路由
	customer := mux.PathPrefix("/customer/").Subrouter()
	customer.HandleFunc("/list", queryStringGetList).Methods(http.MethodGet, http.MethodOptions)
	//customer 子路由使用checkTokenMiddleware
	customer.Use(checkTokenMiddleware)

	http.ListenAndServe(":8080", mux)

}

func queryStringGetList(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintln(w, "URL PATH:", r.URL.Path)
}
func loggingMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		//Do stuff here
		fmt.Fprintln(w, "use loggin middleware:", r.RequestURI)
		// Call the next handler, which can be another middleware in the chain, or the final handler.
		next.ServeHTTP(w, r)
	})
}
func checkTokenMiddleware(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		token := r.Header.Get("Check-Token")
		if token == "" {
			http.Error(w, "Forbidden", http.StatusForbidden)
		} else {
			fmt.Println("request with token:\n", token)

			// Pass down the request to the next middleware (or final handler)
			next.ServeHTTP(w, r)
		}
	})
}

執行結果

//products子路由使用loggingMiddleware
//use loggin middleware: /products/list URL PATH: /products/list
curl --location --request GET '127.0.0.1:8080/products/list'

//customer子路由使用checkTokenMiddleware，會驗證header有沒有帶Check-Token
//有帶header:Check-Token ->URL PATH: /customer/list
//沒帶header:Check-Token ->Forbidden
curl --location --request GET '127.0.0.1:8080/customer/list' \
--header 'Check-Token: GG'

根據上面的執行結果來看，搭配使用mux套件建立的http server彈性與功能比原生net/http套件豐富，
可以視開發情境來選擇使用。