nginx中加入opentracing能力

Why Nginx tracing

Nginx是一個廣泛使用的web原件，常用于反向代理、負載均衡服務器、API網關。在日常的使用中，nginx常常要負責各種redirect、rewrite等服務，對于業務或者調用關系負責的情況，tracing能夠幫助開發者直觀分析請求鏈路，快速定位性能瓶頸，逐漸優化服務間依賴，也有助于開發者從更宏觀的角度更好地理解整個系統。

同時，如果開發者能夠在代碼內部也加入對tracing的支持，那么對于自己開發的服務整體從將可以以上帝視角直觀地看到。

環境要求

nginx stable 1.2+

ngonx-opentracing module

jaeger環境

配置詳情

1. nginx.conf

load_module modules/ngx_http_opentracing_module.so;
user  nobody nobody;
worker_processes  auto;
working_directory /search/odin/nginx/core;
worker_rlimit_core 2G;

error_log  logs/error.log error;

pid        /var/run/nginx.pid;


events {
    use epoll;
    worker_connections  51200;
}


http {
    include       /etc/nginx/mime.types;
    default_type  Application/octet-stream;

    opentracing_load_tracer /usr/local/lib/libjaegertracing_plugin.linux_amd64.so /etc/nginx/conf.d/jaeger-config.json;
    opentracing on;
    opentracing_propagate_context;
    opentracing_operation_name nginx-$host;
    opentracing_tag request.id $request_id;

    index index.html index.htm index.shtml;

    set_real_ip_from   10.0.0.0/8;
    set_real_ip_from   192.168.0.0/16;
    real_ip_header     X-Real-IP;

    log_format main '$host $remote_addr [$time_local] "$request" '
                        '$status $body_bytes_sent "$http_referer" "$http_user_agent" '
                        '$cookie_SUID $request_time $cookie_SSUID '
                        '$http_x_forwarded_for $request_length $cookie_YYID '
                        '$connection_requests "$upstream_addr" $request_id';
    log_format mini '$time_local $status $body_bytes_sent $request_time $upstream_cache_status $server_name';
    access_log "logs/${server_name}_access_log" main;
    access_log logs/status_log mini;


    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    gzip  on;
    gzip_min_length  1024;
    gzip_comp_level  6;
    gzip_types       text/plain text/xml application/x-JAVAscript text/css application/xml;


    include /etc/nginx/conf.d/*.conf;
}

首先，加載nginx 模塊：
ngx_http_opentracing_module.so

load_module modules/ngx_http_opentracing_module.so;

其次，加載并配置jaeger plugin

opentracing_load_tracer /usr/local/lib/libjaegertracing_plugin.linux_amd64.so /etc/nginx/conf.d/jaeger-config.json;
opentracing on; # 啟用opentracing，默認為off
opentracing_propagate_context; # 啟用傳遞context
opentracing_operation_name nginx-$host; # 為請求起個name
opentracing_tag request.id $request_id; # 設置span tag request.id，需要nginx 1.11以上

其中專門設置了一個request.id的tag，這個request.id串起來從nginx到code的所有請求，方便檢索請求

最后，附加一個jaeger的配置，localAgentHostPort需要配置成jaeger-agent所在host:port

{
  "service_name": "nginx",
  "diabled": false,
  "reporter": {
    "logSpans": true,
    "localAgentHostPort": "jaeger:6831"
  },
  "sampler": {
    "type": "const",
    "param": "1"
  }
}

2. server.conf

upstream api{
    server 127.0.0.1:8080;
}

server
{
    listen *:80 default_server;
    server_name xx.test;

    opentracing_location_operation_name $request;
    opentracing_propagate_context;
    proxy_set_header X-Request-Id $request_id;

    proxy_set_header  Host $host;
    proxy_http_version 1.1;

    location ~ ^/api/ {
      proxy_pass http://api;
    }
}

以下三條配置分別設置了location name、啟用傳遞context、設置header X-Request-Id為 $request_id

opentracing_location_operation_name $request;
opentracing_propagate_context;
proxy_set_header X-Request-Id $request_id;

3. 代碼接入opentracing

import (
.....
opentracing "github.com/opentracing/opentracing-go"
"github.com/opentracing/opentracing-go/ext"
)

func (c *AlertManagerController) Webhook() {
	spanCtx, _ := opentracing.GlobalTracer().Extract(opentracing.HTTPHeaders, opentracing.HTTPHeadersCarrier(c.Ctx.Request.Header))
	span := opentracing.GlobalTracer().StartSpan("Webhook", ext.RPCServerOption(spanCtx)) // 關聯為nginx的child
	uuid := c.Ctx.Input.Header("X-Request-Id")
	span.SetTag("request.id", uuid) // 設置request tag
	span.SetBaggageItem("request.id", uuid) // 向后續請求加入request.id
	span.LogKV("request.body", string(c.Ctx.Input.RequestBody))
        ......
}