小白前段时间做Loki分布式追踪时，遇到需要在Nginx这一层生成TraceID和打印traceid相关日志的需求，在网上找了一大圈恁是没找到合适的Docker镜像。

原本应该用opentracing-contrib编译的nginx-opentracing的docker镜像，但是当pull镜像时居然发现它有1.5G的容量，看了Dockerfile才知道这个镜像把Nginx源码和所有编译所需的C库都放在里面，真是佩服。

最后还是得我们自己根据OpenTracing的方法给Nginx安装插件。按照阿里云的文档，小白做了一个Nginx1.14版本镜像提供给大家使用。

quay.io/cloudxiaobai/nginx-jaeger:1.14.0

安装过程参考：https://help.aliyun.com/document_detail/126251.html
zipkin也可以用如上方法炮制

如何使用镜像

1. 首先要启用trace的话，我们需要定义个jaeger的描述配置

jaeger.config

{
  "service_name": "nginx",
  "sampler": {
    "type": "const",
    "param": 1
  },
  "reporter": {
    "localAgentHostPort": "jaeger:6831"
  },
  "headers": {
    #一些默认的jaeger Baggage头设置
    "jaegerDebugHeader": "jaeger-debug-id",
    "jaegerBaggageHeader": "jaeger-baggage",
    "traceBaggageHeaderPrefix": "uberctx-"
  },
  "baggage_restrictions": {
    "denyBaggageOnInitializationFailure": false,
    "hostPort": ""
  }
}

2. nginx也需引入jaeger相关的动态库配置，如下

nginx.conf

# 加载OpenTracing的动态库
load_module modules/ngx_http_opentracing_module.so;

http {
  # 加载Jaeger库
  opentracing_load_tracer /usr/local/lib/libjaegertracing_plugin.so /etc/jaeger-nginx-config.json;

  # 启用Jaeger
  opentracing on;

  # 选择性的注入Tag
  opentracing_tag http_user_agent $http_user_agent;

  upstream backend {
    server app-service:9001;
  }

  location ~ {
    opentracing_operation_name $uri;
    opentracing_propagate_context;
    proxy_pass http://backend;
  }
}

3. 如果我们需要将Trace的日志打印出来，我们可以设置自定义的日志格式：

log_format opentracing '{"timestamp":"$time_iso8601",'
                       '"source":"$server_addr",'
                       '"hostname":"$hostname",'
                       '"ip":"$http_x_forwarded_for",'
                       '"traceID":"$opentracing_context_uber_trace_id",'
                       '"client":"$remote_addr",'
                       '"request_method":"$request_method",'
                       '"scheme":"$scheme",'
                       '"domain":"$server_name",'
                       '"referer":"$http_referer",'
                       '"request":"$request_uri",'
                       '"args":"$args",'
                       '"size":$body_bytes_sent,'
                       '"status": $status,'
                       '"responsetime":$request_time,'
                       '"upstreamtime":"$upstream_response_time",'
                       '"upstreamaddr":"$upstream_addr",'
                       '"http_user_agent":"$http_user_agent",'
                       '"https":"$https"'
                       '}';
                         
 access_log   /dev/stdout opentracing;

这样我们的日志打印出来的json格式

{
    "source": "172.16.0.1",
    "timestamp": "2020-11-02T15:58:15+00:00",
    "args": "-",
    "client": "172.16.0.20",
    "domain": "",
    "hostname": "e7b3c1369b96",
    "http_user_agent": "Ruby",
    "https": "",
    "ip": "-",
    "referer": "-",
    "request": "/loki/api/v1/push",
    "request_method": "POST",
    "responsetime": 0.005,
    "scheme": "http",
    "size": 0,
    "status": 204,
    "traceID": "c39f7c73e43ddd29:c39f7c73e43ddd29:0:1",
    "upstreamaddr": "172.20.0.3:3100",
    "upstreamtime": "0.008"
}

扩展：Ingress-nginx怎么用启用OpenTracing

如果你在kubernetes中用了ingress-nginx作为服务的网关，那么可以直接在ingress中启用opentracing而不用重建镜像。

在启用前，我们需要在ingress-nginx-controller的configmap里面添加如下配置

apiVersion: v1
kind: ConfigMap
data:
  enable-opentracing: "true"
  
  #jaeger的常用篇日志
  jaeger-collector-host: jaeger-agent.default.svc.cluster.local
  jaeger-sampler-param: 1
  jaeger-sampler-type: const

  #zipkin的常用配置
  zipkin-collector-host: zipkin.default.svc.cluster.local
  zipkin-sample-rate: 1.0

  #datadog的常用配置
  datadog-collector-host: datadog-agent.default.svc.cluster.local
  datadog-sample-rate: 1.0
  
metadata:
  name: ingress-nginx-controller
  namespace: kube-system

启用成功后，我们就可以在jaeger里面看到详情了。