nginx流量复制与放大

1. 需求

功能需求

在不影响真实业务前提下，支持：

1. 流量复制，用于线故障分析、系统迁移评估等
2. 流量放大，通过多倍复制，实现放大流量，用于性能压测

配置需求

1. 支持或禁止post请求复制
2. 记录镜像请求的访问日志

2. 解决方案

nginx 1.13.4版本，内置ngx_http_mirror_module模块，能满足上述需求

ngx_http_mirror_module模块特性

1. 相比tcp-copy的优势：无需录制流量，实时可用，配置相当简单
2. 源站请求，直接原路返回
3. 复制请求不影响源站请求，源站nginx-server将流量复制到mirror站后，两者不再有任何交集

3. 配置

下面配置在nginx 1.14.1验证通过，具体配置说明，请看注释信息

3.1 复制请求

server {
        listen       80;
        server_name  web1.www.com;
        # 源站配置
        location / {
                access_log  /data/nginx/1.14.1/logs/web1/access.log  accesslog;
                mirror /mirror;
                mirror_request_body on;# Indicates whether the client request body is mirrored. default value is on.
                proxy_pass http://web1.upstream.name;
        }
        # 镜像站点配置
        location /mirror {
                internal; # 内部配置
                proxy_pass http://mirror.web1.upstream.name$request_uri;
                proxy_pass_request_body on; # Indicates whether the original request body is passed to the proxied server. default value is on
                proxy_set_header X-Original-URI $request_uri; # 使用真实的uri重置uri
        }
}

3.2 不允许复制post请求

默认支持post请求，禁止需要将mirror_request_body修改为off，并判断$request_method

server {
        listen       80;
        server_name  web1.www.com;

        # 源站配置
        location / {
                access_log  /data/nginx/1.14.1/logs/web1/access.log  accesslog;
                mirror /mirror;
                mirror_request_body off;# Indicates whether the client request body is mirrored. default value is on.
                proxy_pass http://web1.upstream.name;
        }

        # 镜像站点配置
        location /mirror {
                # 判断请求方法，不是GET返回403
                if ($request_method != GET) {
                    return 403;
                }
                internal; # 内部配置
                proxy_pass http://mirror.web1.upstream.name$request_uri;
                proxy_pass_request_body off; # Indicates whether the original request body is passed to the proxied server. default value is on
                proxy_set_header Content-Length ""; # mirror_request_body/proxy_pass_request_body都设置为off，则Conten-length需要设置为""，否则有坑
                proxy_set_header X-Original-URI $request_uri; # 使用真实的uri重置uri
        }
}

3.3 流量放大

配置多分mirror

server {
        listen       80;
        server_name  web1.www.com;
        # 源站配置
        location / {
                access_log  /data/nginx/1.14.1/logs/web1/access.log  accesslog;
                mirror /mirror;
                # 多加一份mirror，流量放大一倍
                mirror /mirror;
                mirror_request_body on;# Indicates whether the client request body is mirrored. default value is on.
                proxy_pass http://web1.upstream.name;
        }
        # 镜像站点配置
        location /mirror {
                internal; # 内部配置
                proxy_pass http://mirror.web1.upstream.name$request_uri;
                proxy_pass_request_body on; # Indicates whether the original request body is passed to the proxied server. default value is on
                proxy_set_header X-Original-URI $request_uri; # 使用真实的uri重置uri
        }
}

4. mirror日志

mirror中不支持配置access_log，解决方法：mirror-location跳转到server，在server中配置accesslog.

server {
        listen       80;
        server_name  web1.www.com;

        # 源站配置
        location / {
                access_log  /data/nginx/1.14.1/logs/web1/access.log  accesslog;
                mirror /mirror;
                mirror_request_body off;# Indicates whether the client request body is mirrored. default value is on.
                proxy_pass http://web1.upstream.name;
        }

        # 镜像站点配置
        location /mirror {
                internal; # 内部配置
                # 跳转到下面的内部server
                proxy_pass http://127.0.0.1:10901$request_uri;
                proxy_set_header X-Original-URI $request_uri; # 使用真实的uri重置uri
        }
}

server {
    # server没法设置为内部
    listen 127.0.0.1:10901;
    location / {
        access_log /data/nginx/1.14.1/logs/web1/access.log  accesslog;
        proxy_pass http://mirror.web1.upstream.name;
    }
}

5. 性能评估

• 测试前提：使用jemeter，在相同环境，使用30个并发，各请求3000次get或post方法，参数一样，一组为有mirror配置，另一组为没mirror配置。
• 测试结果：mirror性能损失在5%以内，具体如下：

9. 遇到的问题

9.1 镜像配置不正确时，无日志

镜像配置不正确，导致复制操作没正常执行，但是nginx没有响应的错误日志，严重影响调试。非常建议配置镜像日志，配置方法如4. mirror日志。

9.2 mirror_request_body/proxy_pass_request_body与Content-Length需配置一致

如果mirror_request_body或者proxy_pass_request_body设置为off，则Content-Length必须设置为""，因为nginx/tomcat处理post请求时，会根据Content-Length获取request_body。如果Content-Length不为空，但是把mirror_request_body、proxy_pass_request_body设置为off，nginx/tomcat以为post有内容，但是实际上request_body没有，nginx会报upstream请求超时，tomcat会报如下错误：

"2018-11-08T17:26:36.803+08:00" "331632b86ec64b829672066a96fc6324"      "department"        "group"   "project_name"        "hostname"    "127.0.0.1"     ""      "/post" "p=11"  "-"     "PostmanRuntime/7.1.1"  "ERROR" "xxx.GlobalControllerAdvice"       "operateExp"    "-"     "26"    "xxxx.GlobalControllerAdvice"       "unknown"       "org.springframework.http.converter.HttpMessageNotReadableException"    "I/O error while reading input message; nested exception is java.net.SocketTimeoutException"    "GlobalControllerAdvice中捕获全局异常"  "org.springframework.http.converter.HttpMessageNotReadableException: I/O error while reading input message; nested exception is java.net.SocketTimeoutException
        at org.springframework.web.servlet.mvc.method.annotation.AbstractMessageConverterMethodArgumentResolver.readWithMessageConverters(AbstractMessageConverterMethodArgumentResolver.java:229)
        at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.readWithMessageConverters(RequestResponseBodyMethodProcessor.java:150)
        at org.springframework.web.servlet.mvc.method.annotation.RequestResponseBodyMethodProcessor.resolveArgument(RequestResponseBodyMethodProcessor.java:128)
        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:121)
        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:158)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)

98. 引文

• Module ngx_http_mirror_module
• 流量搬运工，Nginx模块ngx_http_mirror_module
• How to log nginx mirror requests