API Gateway：使用Go語言開發網關外掛程式

Golang

Windows

MacOS

Linux

初始化工程目錄

1. 建立一個工程目錄檔案，例如wasm-demo-go。

2. 在所建目錄下執行以下命令，進行 Go 工程初始化。

   go mod init wasm-demo-go

3. 國內環境可能需要設定下載依賴包的代理。

   go env -w GOPROXY=https://proxy.golang.com.cn,direct

4. 下載構建外掛程式的依賴。

   go get github.com/higress-group/proxy-wasm-go-sdk@go-1.24
   go get github.com/higress-group/wasm-go@main
   go get github.com/tidwall/gjson

編寫 main.go 檔案

package main

import (
  "github.com/higress-group/wasm-go/pkg/wrapper"
  logs "github.com/higress-group/wasm-go/pkg/log"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
  "github.com/tidwall/gjson"
)

func main() {}

func init() {
  wrapper.SetCtx(
    // 外掛程式名稱
    "my-plugin",
    // 為解析外掛程式配置，設定自訂函數
     wrapper.ParseConfigBy(parseConfig),
    // 為處理要求標頭，設定自訂函數
    wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
  )
}

// 自訂外掛程式配置
type MyConfig struct {
  mockEnable bool
}

// 在控制台外掛程式配置中填寫的yaml配置會自動轉換為json，此處直接從json這個參數裡解析配置即可
func parseConfig(json gjson.Result, config *MyConfig, log logs.Log) error {
  // 解析出配置，更新到config中
  config.mockEnable = json.Get("mockEnable").Bool()
  return nil
}

func onHttpRequestHeaders(ctx wrapper.HttpContext, config MyConfig, log logs.Log) types.Action {
  proxywasm.AddHttpRequestHeader("hello", "world")
  if config.mockEnable {
    proxywasm.SendHttpResponse(200, nil, []byte("hello world"), -1)
  }
  return types.HeaderContinue
}

編譯產生 WASM 檔案

go mod tidy
GOOS=wasip1 GOARCH=wasm go build -buildmode=c-shared -o main.wasm ./

工具準備

安裝Docker。

使用docker compose啟動驗證

1. 進入在編寫外掛程式時建立的目錄，例如wasm-demo目錄，確認該目錄下已經編譯產生main.wasm檔案。

2. 在目錄下建立檔案docker-compose.yaml，內容如下：

   version: '3.7'
   services:
     envoy:
       image: higress-registry.cn-hangzhou.cr.aliyuncs.com/higress/gateway:v2.1.5
       entrypoint: /usr/local/bin/envoy
       # 注意這裡對wasm開啟了debug層級日誌，正式部署時則預設info層級
       command: -c /etc/envoy/envoy.yaml --component-log-level wasm:debug
       depends_on:
       - httpbin
       networks:
       - wasmtest
       ports:
       - "10000:10000"
       volumes:
       - ./envoy.yaml:/etc/envoy/envoy.yaml
       - ./main.wasm:/etc/envoy/main.wasm
   
     httpbin:
       image: kennethreitz/httpbin:latest
       networks:
       - wasmtest
       ports:
       - "12345:80"
   
   networks:
     wasmtest: {}

3. 繼續在該目錄下建立檔案envoy.yaml，內容如下：

   admin:
     address:
       socket_address:
         protocol: TCP
         address: 0.0.0.0
         port_value: 9901
   static_resources:
     listeners:
     - name: listener_0
       address:
         socket_address:
           protocol: TCP
           address: 0.0.0.0
           port_value: 10000
       filter_chains:
       - filters:
         - name: envoy.filters.network.http_connection_manager
           typed_config:
             "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
             scheme_header_transformation:
               scheme_to_overwrite: https
             stat_prefix: ingress_http
             route_config:
               name: local_route
               virtual_hosts:
               - name: local_service
                 domains: ["*"]
                 routes:
                 - match:
                     prefix: "/"
                   route:
                     cluster: httpbin
             http_filters:
             - name: wasmdemo
               typed_config:
                 "@type": type.googleapis.com/udpa.type.v1.TypedStruct
                 type_url: type.googleapis.com/envoy.extensions.filters.http.wasm.v3.Wasm
                 value:
                   config:
                     name: wasmdemo
                     vm_config:
                       runtime: envoy.wasm.runtime.v8
                       code:
                         local:
                           filename: /etc/envoy/main.wasm
                     configuration:
                       "@type": "type.googleapis.com/google.protobuf.StringValue"
                       value: |
                         {
                           "mockEnable": false
                         }
             - name: envoy.filters.http.router
               typed_config:
                 "@type": type.googleapis.com/envoy.extensions.filters.http.router.v3.Router
     clusters:
     - name: httpbin
       connect_timeout: 30s
       type: LOGICAL_DNS
       # Comment out the following line to test on v6 networks
       dns_lookup_family: V4_ONLY
       lb_policy: ROUND_ROBIN
       load_assignment:
         cluster_name: httpbin
         endpoints:
         - lb_endpoints:
           - endpoint:
               address:
                 socket_address:
                   address: httpbin
                   port_value: 80

4. 執行以下命令啟動docker compose。

   docker compose up

功能驗證

無配置外掛程式

外掛程式無需配置時，直接定義空結構體即可。

package main

import (
  "github.com/higress-group/wasm-go/pkg/wrapper"
  logs "github.com/higress-group/wasm-go/pkg/log"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
)

func main() {}

func init() {
  wrapper.SetCtx(
    "hello-world",
    wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
  )
}

type MyConfig struct {}

func onHttpRequestHeaders(ctx wrapper.HttpContext, config MyConfig, log logs.Log) types.Action {
  proxywasm.SendHttpResponse(200, nil, []byte("hello world"), -1)
  return types.HeaderContinue
}

在外掛程式中請求外部服務

目前僅支援 http 調用，支援訪問在網關控制台中設定了服務來源的 Nacos、K8s 服務，以及固定地址或 DNS 來源的服務。請注意，無法直接使用net/http庫中的 HTTP client，必須使用如下例中封裝的 HTTP client。

下面例子中，在配置解析階段解析服務類型，產生對應的 HTTP client ；在要求標頭處理階段根據配置的請求路徑訪問對應服務，解析應答頭，然後再設定在原始的要求標頭中。

package main

import (
  "errors"
  "net/http"
  "strings"
  "github.com/higress-group/wasm-go/pkg/wrapper"
  logs "github.com/higress-group/wasm-go/pkg/log"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
  "github.com/tidwall/gjson"
)

func main() {}

func init() {
  wrapper.SetCtx(
    "http-call",
    wrapper.ParseConfigBy(parseConfig),
    wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
  )
}

type MyConfig struct {
  // 用於發起HTTP調用client
  client      wrapper.HttpClient
  // 請求url
  requestPath string
  // 根據這個key取出調用服務的應答頭對應欄位，再設定到原始請求的要求標頭，key為此配置項
  tokenHeader string
}

func parseConfig(json gjson.Result, config *MyConfig, log logs.Log) error {
  config.tokenHeader = json.Get("tokenHeader").String()
  if config.tokenHeader == "" {
    return errors.New("missing tokenHeader in config")
  }
  config.requestPath = json.Get("requestPath").String()
  if config.requestPath == "" {
    return errors.New("missing requestPath in config")
  }
  // 帶服務類型的完整 FQDN 名稱，例如 my-svc.dns, my-svc.static, service-provider.DEFAULT-GROUP.public.nacos, httpbin.my-ns.svc.cluster.local
  serviceName := json.Get("serviceName").String()
  servicePort := json.Get("servicePort").Int()
  if servicePort == 0 {
    if strings.HasSuffix(serviceName, ".static") {
      // 靜態IP類型服務的邏輯連接埠是80
      servicePort = 80
    }
  }
  config.client = wrapper.NewClusterClient(wrapper.FQDNCluster{
    FQDN: serviceName,
    Port: servicePort,
        })
}

func onHttpRequestHeaders(ctx wrapper.HttpContext, config MyConfig, log logs.Log) types.Action {
  // 使用client的Get方法發起HTTP Get調用，此處省略了timeout參數，預設逾時時間500毫秒
  err := config.client.Get(config.requestPath, nil,
           // 回呼函數，將在響應非同步返回時被執行
           func(statusCode int, responseHeaders http.Header, responseBody []byte) {
             // 請求沒有返回200狀態代碼，進行處理
             if statusCode != http.StatusOK {
               log.Errorf("http call failed, status: %d", statusCode)
               proxywasm.SendHttpResponse(http.StatusInternalServerError, nil,
                 []byte("http call failed"), -1)
               return
             }
             // 列印響應的HTTP狀態代碼和應答body
             log.Infof("get status: %d, response body: %s", statusCode, responseBody)
             // 從應答頭中解析token欄位設定到原始要求標頭中
             token := responseHeaders.Get(config.tokenHeader)
             if token != "" {
               proxywasm.AddHttpRequestHeader(config.tokenHeader, token)
             }
             // 恢複原始請求流程，繼續往下處理，才能正常轉寄給後端服務
             proxywasm.ResumeHttpRequest()
    })

  if err != nil {
    // 由於調用外部服務失敗，允許存取請求，記錄日誌
    log.Errorf("Error occured while calling http, it seems cannot find the service cluster.")
    return types.ActionContinue
  } else {
    // 需要等待非同步回調完成，返回HeaderStopAllIterationAndWatermark狀態，可以被ResumeHttpRequest恢複
    return types.HeaderStopAllIterationAndWatermark
  }
}

在外掛程式中調用Redis

使用如下範例程式碼實現Redis限流外掛程式。

package main

import (
  "strconv"
  "time"

  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm"
  "github.com/higress-group/proxy-wasm-go-sdk/proxywasm/types"
  "github.com/tidwall/gjson"
  "github.com/tidwall/resp"

  "github.com/higress-group/wasm-go/pkg/wrapper"
  logs "github.com/higress-group/wasm-go/pkg/log"
)

func main() {}

func init() {
  wrapper.SetCtx(
    "redis-demo",
    wrapper.ParseConfigBy(parseConfig),
    wrapper.ProcessRequestHeadersBy(onHttpRequestHeaders),
    wrapper.ProcessResponseHeadersBy(onHttpResponseHeaders),
  )
}

type RedisCallConfig struct {
  client wrapper.RedisClient
  qpm    int
}

func parseConfig(json gjson.Result, config *RedisCallConfig, log logs.Log) error {
  // 帶服務類型的完整 FQDN 名稱，例如 my-redis.dns、redis.my-ns.svc.cluster.local
  serviceName := json.Get("serviceName").String()
  servicePort := json.Get("servicePort").Int()
  if servicePort == 0 {
    if strings.HasSuffix(serviceName, ".static") {
      // 靜態IP類型服務的邏輯連接埠是80
      servicePort = 80
    } else {
      servicePort = 6379
    }
  }
  username := json.Get("username").String()
  password := json.Get("password").String()
  // 單位是毫秒
  timeout := json.Get("timeout").Int()
  if timeout == 0 {
    timeout = 1000
  }
  qpm := json.Get("qpm").Int()
  config.qpm = int(qpm)
  config.client = wrapper.NewRedisClusterClient(wrapper.FQDNCluster{
    FQDN: serviceName,
    Port: servicePort,
  })
  return config.client.Init(username, password, timeout)
}

func onHttpRequestHeaders(ctx wrapper.HttpContext, config RedisCallConfig, log logs.Log) types.Action {
  now := time.Now()
  minuteAligned := now.Truncate(time.Minute)
  timeStamp := strconv.FormatInt(minuteAligned.Unix(), 10)
  // 如果 redis api 返回的 err != nil，一般是由於網關找不到 redis 後端服務，請檢查是否誤刪除了 redis 後端服務
  err := config.client.Incr(timeStamp, func(response resp.Value) {
    if response.Error() != nil {
      log.Errorf("call redis error: %v", response.Error())
      proxywasm.ResumeHttpRequest()
    } else {
      ctx.SetContext("timeStamp", timeStamp)
      ctx.SetContext("callTimeLeft", strconv.Itoa(config.qpm-response.Integer()))
      if response.Integer() == 1 {
        err := config.client.Expire(timeStamp, 60, func(response resp.Value) {
          if response.Error() != nil {
            log.Errorf("call redis error: %v", response.Error())
          }
          proxywasm.ResumeHttpRequest()
        })
        if err != nil {
          log.Errorf("Error occured while calling redis, it seems cannot find the redis cluster.")
          proxywasm.ResumeHttpRequest()
        }
      } else {
        if response.Integer() > config.qpm {
          proxywasm.SendHttpResponse(429, [][2]string{{"timeStamp", timeStamp}, {"callTimeLeft", "0"}}, []byte("Too many requests\n"), -1)
        } else {
          proxywasm.ResumeHttpRequest()
        }
      }
    }
  })
  if err != nil {
    // 由於調用redis失敗，允許存取請求，記錄日誌
    log.Errorf("Error occured while calling redis, it seems cannot find the redis cluster.")
    return types.HeaderContinue
  } else {
    // 請求hold住，等待redis調用完成
    return types.HeaderStopAllIterationAndWatermark
  }
}

func onHttpResponseHeaders(ctx wrapper.HttpContext, config RedisCallConfig, log logs.Log) types.Action {
  if ctx.GetContext("timeStamp") != nil {
    proxywasm.AddHttpResponseHeader("timeStamp", ctx.GetContext("timeStamp").(string))
  }
  if ctx.GetContext("callTimeLeft") != nil {
    proxywasm.AddHttpResponseHeader("callTimeLeft", ctx.GetContext("callTimeLeft").(string))
  }
  return types.HeaderContinue
}