nginx手机用户访问自适应页面详解

1. 当后端服务器出现异常，响应码为500 501 502 503 504，请求转发到静态降级服务器，从而保证业务不至于完全无法访问，对于浏览型且实时性要求不高的站点非常有用。

app_servers：应用服务器，提供正常服务页面

shopwebstatic：静态服务器，提供定时爬取的静态页面

2.请求重试：

proxy_next_upstream http_500 http_502 http_504 error timeout invalid_header;

3.根据user agent,cookie特定字段，将来源为PC版用户的请求转发到手机版页面或者恢复访问PC版本页面。

默认手机用户访问站点会跳转到手机版本，跳转判断依据是user agent，当用户点击访问电脑版本的时候，除了要判断用户的user agent外还需要判断用户的访问模式，通过cookie中特定字段的值来判断用户访问请求是到手机版本还是到PC版本。

mode=pc，mode标记用户的访问模式是PC版本，通过此cookie字段，可判断是否将user agent匹配智能手机字段的用户的请求转发到手机版本。

limit_conn_zone $server_name zone=limit:10m;
upstream app_servers {
server app_server01_ip:80 weight=1 max_fails=2;
  server app_server01_ip:80 weight=1 max_fails=2 backup;
}
upstream shopwebstatic {
  server shopwebstatic_server01_ip:80 weight=5;
  server shopwebstatic_server02_ip:80 weight=5;
}
server {
  listen 80;
  server_name qunying.liu.dianping.com;
  # config_apps_begin
  root /data/webapps/shops-web/shared/webroot;
  access_log logs/shops-web.access.log main;
  error_log logs/shops-web.error.log notice;
  # config_apps_end
  limit_conn limit 280;
  proxy_next_upstream http_500 http_502 http_504 error timeout invalid_header;
  location / {
  proxy_intercept_errors on;
  location ~* ^/shop/(\d+)/menu{
    set $mobile 0;
    set $shopid $1;
    set $hostid 0;
  if ( $http_user_agent ~* "(Android|iPhone|Windows Phone)" ){
    set $mobile "${mobile}1";
  }
  if ( $host ~* "m\.dianping\.com" ){
    set $hostid "${hostid}1";
  }
  if ( $http_cookie !~* "mode=pc"){
    set $mobile "${mobile}1";
  }
  if ( $hostid = "01" ){
    proxy_pass http://app_servers/shop/$shopid/mobilemenu;
    break;
  }
  if ( $mobile = "011" ){
    rewrite ^/(.*)$ http://mobile-servers/$1 redirect;
    break;
  }
  proxy_pass http://app_servers;
    break;
  }
  location ~* ^/shop/(\d+)/dish-(.*){
    set $mobile 0;
    set $shopid $1;
    set $dishurl $2;
  if ( $http_user_agent ~* "(Android|iPhone|Windows Phone)" ){
    set $mobile "${mobile}1";
  }
  if ( $http_cookie !~* "mode=pc"){
    set $mobile "${mobile}1";
  }
  if ( $mobile = "011" ){
    rewrite ^/(.*)$ http://mobile-servers/shop/$shopid/product-$dishurl redirect;
    break;
  }
  proxy_pass http://app_servers;
    break; 
  }
  location ~* ^/map/shop/(\d+)$ {
  set $shopid $1;
  rewrite ^/(.*)$ http://www.servers/shop/$shopid/map permanent;
  proxy_set_header Host "www.servers";
    break;
  }
  location ~* ^/shop/(\d+)(/map|/)?$ {
  set $mobile 0;
  if ( $http_user_agent ~* "(Android|iPhone|Windows Phone)" ){
    set $mobile "${mobile}1";
  }
  if ( $http_cookie !~* "mode=pc"){
    set $mobile "${mobile}1";
  }
  if ( $mobile = "011" ){
    rewrite ^/(.*)$ http://mobile-servers/$1 redirect;
    break;
  }
  proxy_pass http://app_servers;
    break;
  }
  # appserverfavcion
  location ~* ^.*/favicon.ico$ {
    root /data/webapps;
    expires 30d;
    break;
  }
  if ( !-f $request_filename ) {
    proxy_pass http://app_servers;
    break;
  }
}
error_page 500 501 502 503 504 @shopstatic;
  location @shopstatic {
  access_log logs/shops-static-web.access.log retry;
  proxy_pass http://shopwebstatic;
}

发现过去配置的规则中，由于未判断访问的主机名导致当一个应用同时被配置在pc和手机域名下，当访问pc版本域名跳转手机版本时会产生死循环重定向，如www（手机访问时）----自动跳转到m域名---m域名解析到应用会再根据user agent和cookie规则跳转一次m域名，然后陷入死循环。

在做域名跳转的时候，最好对域名做一个判断。

location ~* /mylist/{
set $mobile 0;
if ( $http_user_agent ~* "(Android|iPhone|Windows Phone|UC|Kindle)" ){
  set $mobile "${mobile}1";
}
if ( $http_host !~ "m.dianping.com" ){
  set $mobile "${mobile}2";
}
if ( $cookie_vmod !~ "pc" ){
  set $mobile "${mobile}3";
}
if ( $mobile = "0123" ){
  rewrite ^/(.*)$ http://m.dianping.com/$1 last;
  break;
}
  proxy_pass http://jboss8080;
  break;
}