What is the difference between text and variable with this text in Nginx?

Question

nginx:1.21.5 docker container.

there is two similar (as I think) configs:

server {
...
set $target_token "http://token-container:80";
  location /token/ {
    proxy_pass $target_token/;
    expires -1;
    proxy_read_timeout 60;
    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 X-Forwarded-Proto  $scheme;
    }
}

and

server {
...
  location /token/ {
    proxy_pass http://token-container:80/;
    expires -1;
    proxy_read_timeout 60;
    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 X-Forwarded-Proto  $scheme;
    }
}

First one has problems with cashing. (loaded page is blank. js didnt loaded)

Please look at the picture: (all items sizes are the same)

And the same page with the second config:

Why the usage of the variable spoil the page caching behavior?

Answer 1

Variable in the proxy_pass force you to handle URI too, otherwise it will be dropped. Something like this proxy_pass $upstream/api/$1$is_args$args;

I got it from: External resource: dev.to. Author: Daniel Albuschat