nginx 启动失败和数据库插入失败 - 研发周记 180720

研发周记，记录一周研发中遇到的疑难杂症，本周的研发中主要遇到两个问题，一个是 nginx 启动失败另一个是 mysql数据插入失败，下面我们进入主题吧。

nginx 启动失败

突然发现，沙沙野的用户登录系统不工作了，立马登录服务器查看，发现nginx没有运行，于是乎，systemctl start nginx 问题解决，结果第二天同样的问题再次诞生，而在此之前nginx 开机是能自启的，唯一的不同是修改了nginx配置文件。

于是第二天没有立马 start 而是查看log systemctl status nginx -l 发现输出如下：

● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since 五 2018-07-20 16:27:53 CST; 17s ago

7月 20 16:27:53 izbp17twuiujek64ahvc5tz systemd[1]: Starting The nginx HTTP and reverse proxy server...
7月 20 16:27:53 izbp17twuiujek64ahvc5tz nginx[968]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
7月 20 16:27:53 izbp17twuiujek64ahvc5tz nginx[968]: nginx: [emerg] no "events" section in configuration
7月 20 16:27:53 izbp17twuiujek64ahvc5tz nginx[968]: nginx: configuration file /etc/nginx/nginx.conf test failed
7月 20 16:27:53 izbp17twuiujek64ahvc5tz systemd[1]: nginx.service: control process exited, code=exited status=1
7月 20 16:27:53 izbp17twuiujek64ahvc5tz systemd[1]: Failed to start The nginx HTTP and reverse proxy server.
7月 20 16:27:53 izbp17twuiujek64ahvc5tz systemd[1]: Unit nginx.service entered failed state.
7月 20 16:27:53 izbp17twuiujek64ahvc5tz systemd[1]: nginx.service failed.

而如果执行 systemctl start nginx 后再次查看log，则输出如下：

● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
   Active: active (running) since 五 2018-07-20 16:28:26 CST; 37s ago
  Process: 1616 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 1614 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
  Process: 1612 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, status=0/SUCCESS)
 Main PID: 1619 (nginx)
   CGroup: /system.slice/nginx.service
           ├─1619 nginx: master process /usr/sbin/ngin
           ├─1620 nginx: worker proces
           ├─1621 nginx: cache manager proces
           └─1622 nginx: cache loader proces

7月 20 16:28:25 izbp17twuiujek64ahvc5tz systemd[1]: Starting The nginx HTTP and reverse proxy server...
7月 20 16:28:26 izbp17twuiujek64ahvc5tz nginx[1614]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
7月 20 16:28:26 izbp17twuiujek64ahvc5tz nginx[1614]: nginx: configuration file /etc/nginx/nginx.conf test is successful
7月 20 16:28:26 izbp17twuiujek64ahvc5tz systemd[1]: Failed to read PID from file /run/nginx.pid: Invalid argument
7月 20 16:28:26 izbp17twuiujek64ahvc5tz systemd[1]: Started The nginx HTTP and reverse proxy server.

通过分析出错时的log，可以确定问题是 nginx.conf 有问题，而我由于有特殊需求，每次开机部署项目，会将 nginx.conf 覆盖，那么应该是覆盖和 nginx 启动几乎同时发生了，导致nginx启动的时候读取不了nginx.conf而稍等一会文件覆盖一旦完成则可以启动了，为了验证是否如此，我关闭了开机部署项目时覆盖nginx.conf的选项。然后再重启，一切正常，问题至此结束。