using $upstream* variables inside map directive

[unoobee]

My configuration looks like this:

proxy_cache_path /cache/ssd              keys_zone=ssd_cache:10m levels=1:2
inactive=600s max_size=100m;
proxy_cache_path /cache/hdd              keys_zone=hdd_cache:10m levels=1:2
inactive=600s max_size=100m;

upstream backend {
        server www.test.com:443;
}

server {
    listen 80;
    server_name test.com;
        
        location / {
            proxy_pass https://backend;
            proxy_redirect https://backend/ /;
            proxy_set_header Host $host;
            proxy_cache $cache;
        }
}


map $upstream_http_content_length $cache  {
       volatile;
        ~^\d\d\b    ssd_cache;
        default     hdd_cache;
}

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,249880,289965#msg-289965