zk spring boot behind a proxy ( nginx )

I created zk application using zk spring boot starter. Everything works correctly.

SpringBootApplication.java:

@SpringBootApplication
@Controller
public class SpringBootApplication {
	@GetMapping("${application.base-path:}/{page}")
    public String view(@PathVariable String page) {
        return page;
    }

    public static void main(String[] args) {
        SpringApplication.run(SpringBootBesGuiApplication.class, args);
    }
}

project's structure:

.....................
src/main/resources
 |
  -- web
      js
        - script1.js
        - script2.js
      - page1.zul
      - page2.zul
.....................

page1.zul:

...................
<?script src="~./js/script1.js"?>
...................

http://my-server:8081/page1 is displaying correctly.

And after that I tried to run it behind a proxy ( nginx ). And the page is displaying nothing. There are errors in a browser console:

GET http://my-server/zkau/web/162740bd/_zkiju-sapphire/zul/css/zk.wcs net::ERR_ABORTED 502 (Bad Gateway)	
........................................................................................
GET http://my-server/zkau/web/162740bd/js/script1.js net::ERR_ABORTED 502 (Bad Gateway)
........................................................................................

It seems that there are wrong url's generated for *.wcs, *.wpd and my *.js files.
What am I doing wrong? How can I repair it?

nginx.conf:

server {
listen 80;
server_name my-server;

........................................
    
location / {
proxy_pass http://my-server:8080;
fastcgi_read_timeout 300;
}
    
location /app {
proxy_set_header X-Forwarded-Host $host;
proxy_set_header X-Forwarded-Server $host;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_pass http://my-server:8081;
fastcgi_read_timeout 300;
}
.............................................
}

application.properties:

application.base-path=/app

I resolve the issue by changing configs:

application.properties

server.servlet.context-path=/app

nginx.conf

..........
proxy_pass http://my-server:8081/app;
..........

Thanks, @cor3000 and @protonchang. Yes, It's not ZK issue.

comparing it to other tutorials (e.g. https://clouding.io/hc/en-us/articles/360010806999-How-to-Deploy-Spring-Boot-Application-with-Nginx-on-Ubuntu-18-04) it looks like at least a trailing '/' might be missing on the

proxy_pass http://my-server:8081

vs

proxy_pass http://my-server:8081/

I hope some nginx-experts can confirm this, or give more details. From the ZK side there's nothing you can/have to configure when using a proxy around a webapplication.

You can try turning on access_log and error_log, if there's a proxy_pass upstream error, you should be able to identify that.

From the configuration you provided, you can try using @cor3000's answer.
Your current configuration will route /zkau/web/* to port 8080, so make sure you can get those data from that springboot instance.