之前用docker-compose启动nginx和后端程序时，后端程序如果在nginx后启动会造成报错。虽然可以使用docker-compose的depend on 解决还是不够优雅。

所以考虑使用upstream解决。

原始配置

server {
    listen       80;
    listen  [::]:80;
    server_name  gitlab.example.com;
    client_max_body_size 500M;

    location =/robots.txt {
        default_type text/html;
        add_header Content-Type "text/plain; charset=UTF-8";
        return 200 "User-Agent: *\nDisallow: /";
    }

    #forbidden UA
    if ($http_user_agent ~ "Bytespider|FeedDemon|JikeSpider|Indy Library|Alexa Toolbar|AskTbFXTV|AhrefsBot|CrawlDaddy|CoolpadWebkit|Java|Feedly|UniversalFeedParser|ApacheBench|Microsoft URL Control|Swiftbot|ZmEu|oBot|jaunty|Python-urllib|python-requests|lightDeckReports Bot|YYSpider|DigExt|YisouSpider|HttpClient|MJ12bot|heritrix|EasouSpider|Ezooms|^$" ) {

      return 403;
    }

    location / {
        proxy_pass http://frps:4000;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

修改后的配置

upstream git-backend {
    server frps:4000;
}
server {
    listen       80;
    listen  [::]:80;
    server_name  gitlab.example.com;
    client_max_body_size 500M;

    location =/robots.txt {
        default_type text/html;
        add_header Content-Type "text/plain; charset=UTF-8";
        return 200 "User-Agent: *\nDisallow: /";
    }

    #forbidden UA
    if ($http_user_agent ~ "Bytespider|FeedDemon|JikeSpider|Indy Library|Alexa Toolbar|AskTbFXTV|AhrefsBot|CrawlDaddy|CoolpadWebkit|Java|Feedly|UniversalFeedParser|ApacheBench|Microsoft URL Control|Swiftbot|ZmEu|oBot|jaunty|Python-urllib|python-requests|lightDeckReports Bot|YYSpider|DigExt|YisouSpider|HttpClient|MJ12bot|heritrix|EasouSpider|Ezooms|^$" ) {

      return 403;
    }

    location / {
        proxy_pass http://git-backend;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

修改点如下：

将proxy_pass后的主机名和端口定义为upstream,然后修改proxy_pass的值为upstream的名。

修改完后 启动nginx无需等待后端启动完成即可自行启动