空指针+nginx配置导致的502

蔚落 2023-01-04 10:23 90阅读 0赞

问题描述：  
服务的不同接口不间断的报出502，分布在不同的接口和不同的nginx服务上，很是怪异。

竞赛生产日志平台：  
nginx中的error.log  
2020/12/23 16:59:59 \[error\] 22636\#0: \*380224130 no live upstreams while connecting to upstream, client: 100.117.86.88, server: aa.code.com, request: "GET /api/competit  
ion/process/student/detail?competitionId=127 HTTP/1.1", upstream: "http://aa\_xes/api/competition/process/student/detail?competitionId=127", host: "aa.code.com", r  
eferrer: "https://aa.code.com/?id=c6a4761c4b3974d6fe56d77c8ebe3a0a&code=7597a7b2e4d0c50ac96db0cefca6f30448bda50049bf3307ab4a5e4e030afb88796788528826034928717be5efd3da6  
e"  
2020/12/23 16:59:59 \[error\] 22636\#0: \*380224133 no live upstreams while connecting to upstream, client: 100.117.86.51, server: aa.code.com, request: "GET /api/competit  
ion/user/public/getCompPage?id=c6a4761c4b3974d6fe56d77c8ebe3a0a HTTP/1.1", upstream: "http://aa\_xes/api/competition/user/public/getCompPage?id=c6a4761c4b3974d6fe56d77c8ebe3a0  
a", host: "aa.code.com", referrer: "https://aa.code.com/?id=c6a4761c4b3974d6fe56d77c8ebe3a0a&code=443082759c2302f47aa47b7c0a92bed72bc1f473c4da309c7e5650e7d  
3e662e1"

access.log 中的错误日志  
\{"@timestamp":"2020-12-23T17:56:29+08:00","cookie\_id":"-","client\_ip":"100.117.86.102","remote\_user":"-","request\_method":"GET","domain":"aa.code.com","user\_agent":"Mo  
zilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36","xff":"218.79.230.248","upstream\_addr":"172.16.1.52:8380","upstr  
eam\_response\_time":"0.017","request\_time":"0.017","size":"113","idc\_tag":"tjtx","status":"500","upstream\_status":"500","host":"bcy-nginx01","via":"-","protocol":"http","request\_ur  
i":"/api/competition/process/student/detail?competitionId=127","http\_referer":"https://aa.code.com/?id=c6a4761c4b3974d6fe56d77c8ebe3a0a&code=3e2418e23c5b47051dfd61ce13  
b6f5916c7ff04509bfb837ebb7d08b2d85912f"\}

服务中的错误日志  
2020-12-23 18:12:50.355\[ERROR\]\[  XNIO-1 task-4\]       c.t.c.w.e.GlobalExceptionHandler        : \[Handle\_Exception\] - java.lang.NullPointerException  
        at com.tal.competition.service.CompetitionProcessItemService.lambda$findStudentProcesses$2(CompetitionProcessItemService.java:385)  
        at java.base/java.util.ArrayList.forEach(ArrayList.java:1507)  
        at com.tal.competition.service.CompetitionProcessItemService.findStudentProcesses(CompetitionProcessItemService.java:332)

先理解upstream upstream jingsai\_xes \{  
      server 172.16.1.53:8380;  
      server 172.16.1.51:8380;  
      server 172.16.1.48:8380;  
      server 172.16.1.49:8380;  
      server 172.16.1.47:8380;  
      server 172.16.1.52:8380;  
      server 172.16.1.44:8380;  
      server 172.16.1.50:8380;  
      server 172.16.1.45:8380;  
      server 172.16.1.46:8380;  
      check interval=2000 rise=2 fall=1 timeout=1000 type=tcp port=8380;  
 \}  
 这些都是配置的upstream。

proxy\_next\_upstream含义：如果某个机器上的幂等服务报错，则会到下一个upstream(服务器)  
max\_fails参数的理解：根据上面的解释，max\_fails默认为1，fail\_timeout默认为10秒，也就是说，默认情况下后端服务器 在10秒钟之内可以容许有一次的失败，如果超过1次则视为该服务器有问题，将该服务器标记为不可用。等待10秒后再将请求发给该服务器  
参考：http://blog.chinaunix.net/uid-29580597-id-4415903.html

check interval=2000 rise=2 fall=1 timeout=1000 type=tcp port=8098;  
\#对负载均衡池中的所有节点，每个2秒检测一次，请求2次正常则标记realserver状态为up，如果检测2次都失败，标记realserver的状态为down，后端健康请求的超时时间为1s，健康检查包的类型为http请求。

把这个配置加进去，变成： proxy\_next\_upstream error timeout http\_500 non\_idemponent; 问题终于解决了。  
这段话的意思是说，像 post, lock, patch 这种会对服务器造成不幂等的方法，默认是不进行重试的，如果一定要进行重试，则要加上这个配置。  
参考：https://zhuanlan.zhihu.com/p/35803906

单台nginx认定所有服务时效的场景：  
如果该台机器10秒内调用 /api/competition/process/student/detail?competitionId=127

本质原因：  
127请求进入nginx，转到某个服务器报了500，请求会在所有机器转发一遍，如果127这个请求10秒内两次达到机器上，nginx就认为所有机器不可用,报出no live upstreams while connecting to upstrea

为什么只有竞赛有该问题？  
proxy\_next\_upstream中没有配置http\_500

5时0分钟errlog统计  
nginx 01    
只有7-14秒没有报 no live upstreams while connecting to upstream  
且accessLog说明  07-08秒有请求进入

nginx 02   
16-20秒没有报 no live upstreams while connecting to upstream

nginx 03  
02-06 29-32 41-45 54-60

秒没有报 no live upstreams while connecting to upstream

配置修改  
proxy\_next\_upstream\_tries 3  
status code 返回的是 502

server \{  
         listen        80;  
        server\_name   aa.code.com;  
        proxy\_next\_upstream   http\_500  http\_502 http\_503 http\_504 error timeout invalid\_header;  
        proxy\_set\_header Accept-Encoding "";  
        client\_max\_body\_size 64M;  
        access\_log      /data/log/nginx/aa-access.log main\_json;  
        location / \{  
            proxy\_read\_timeout      3600;  
            proxy\_connect\_timeout   300;  
            proxy\_set\_header Host $http\_host;  
            proxy\_set\_header X-Real-IP $remote\_addr;  
            proxy\_set\_header X-Forwarded-For $proxy\_add\_x\_forwarded\_for;  
            proxy\_set\_header X-Forwarded-Proto https;  
            root /data/webroot/cp-website/;  
        \}

修改后nginx的配置（即在proxy\_next\_upstream 中去掉了http\_502）  
    server \{  
         listen        80;  
        server\_name   aa.code.com;  
        proxy\_next\_upstream     http\_502 http\_503 http\_504 error timeout invalid\_header;  
        proxy\_set\_header Accept-Encoding "";  
        client\_max\_body\_size 64M;  
        access\_log      /data/log/nginx/aa-access.log main\_json;  
        location / \{  
            proxy\_read\_timeout      3600;  
            proxy\_connect\_timeout   300;  
            proxy\_set\_header Host $http\_host;  
            proxy\_set\_header X-Real-IP $remote\_addr;  
            proxy\_set\_header X-Forwarded-For $proxy\_add\_x\_forwarded\_for;  
            proxy\_set\_header X-Forwarded-Proto https;  
            root /data/webroot/cp-website/;  
        \}

相似问题博客:  
https://blog.csdn.net/piaohai/article/details/102753168 Nginx 502问题排查 - proxy\_next\_upstream  
https://blog.51cto.com/zhangshujian/1092800 Nginx 502 503 错误触发条件与解决办法汇总

nginx500转502 原因汇总：  
supvisor ctrl  
nginx机器配置  
内部后台服务500，被转成了502