nginx - 设置 nginx 在找不到上游主机时不会崩溃

Question

我们在 Docker 的公共(public)域下有几个 Rails 应用程序，我们使用 nginx 将请求定向到特定应用程序。

our_dev_server.com/foo # proxies to foo app
our_dev_server.com/bar # proxies to bar

配置如下:

upstream foo {
  server foo:3000;
}

upstream bar {
  server bar:3000;
}

# and about 10 more...

server {
  listen *:80 default_server;

  server_name our_dev_server.com;

  location /foo {
      # this is specific to asset management in rails dev
      rewrite ^/foo/assets(/.*)$ /assets/$1 break;
      rewrite ^/foo(/.*)$ /foo/$1 break;
      proxy_pass http://foo;
  }

  location /bar {
      rewrite ^/bar/assets(/.*)$ /assets/$1 break;
      rewrite ^/bar(/.*)$ /bar/$1 break;
      proxy_pass http://bar;
  }

  # and about 10 more...
}

如果这些应用程序之一未启动，则 nginx 会失败并停止:

host not found in upstream "bar:3000" in /etc/nginx/conf.d/nginx.conf:6

我们不需要它们全部启动，但否则 nginx 会失败。如何让 nginx 忽略失败的上游？

Answer 1

1. 如果您可以使用静态 IP，那么只需使用它，它就会启动，如果没有响应，则返回 503。

2. 使用resolver指令来指向可以解析主机的东西，无论它当前是否启动。

3. 如果您无法执行上述操作，请在位置级别解决该问题(这将允许 Nginx 启动/运行):

    location /foo {
      resolver 127.0.0.1 valid=30s;
      # or some other DNS (your company's internal DNS server)
      #resolver 8.8.8.8 valid=30s;
      set $upstream_foo foo;
      proxy_pass http://$upstream_foo:80;
    }
   
    location /bar {
      resolver 127.0.0.1 valid=30s;
      # or some other DNS (your company's internal DNS server)
      #resolver 8.8.8.8 valid=30s;
      set $upstream_bar foo;
      proxy_pass http://$upstream_bar:80;
    }