server {
    listen       80;
    listen  [::]:80;
    server_name  localhost;

    #access_log  /var/log/nginx/host.access.log  main;

    location / {
        root   /app;
        if (!-e $request_filename) {
           rewrite  ^(.*)$  /index.html  last;
           break;
        }
    }

    location ^~/api {
        proxy_pass $APP_API_URL;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header REMOTE-HOST $remote_addr;
        proxy_set_header Upgrade $http_upgrade;
        proxy_http_version 1.1;
        proxy_ssl_verify off;
        # proxy_hide_header Upgrade;

        add_header X-Cache $upstream_cache_status;
    }
}