Caddy cache_handler object and memory limits

[Forza]

I got interested in cache_handler from the thread Increase cache entry size when using minimal cache configuration

I’ve been reading up on the example configurations but there are a few things I don’t quite understand.

First, is there a way to define maximum memory usage for the entire cache? Secondly, how can we limit the size of the objects stored in the cache, that is allow objects >n and/or <n size?

Since I couldn’t find a suitable example, I tried the Redis back-end as Redis can be configured as a ram cache with automatic eviction according to LFU or LRU. Unfortunately, there is a bug preventing keys from being stored in Redis.

What I would like to achieve is:

• Set a RAM usage limit for the cache as a whole.
• Optionally have a disk based cache for objects not in ram.
• Be able to set a maximum object size to prevent very large files from consuming the cache and evict all other objects.

My use case is primarily to cache responses from a file server (a repo mirror) that this Caddy instance is a reverse proxy for.

Would this be possible to achieve using any of the existing back-ends to the cache-handler plugin?

This is my current setup using Redis back-end.

{
    # debug
    auto_https off
    log {
        output file /var/log/caddy/caddy_main.log {
            roll_disabled
        }
        format json
    }
    servers {
        metrics
        trusted_proxies cloudflare
    }
    cache {
        redis {
            configuration {
                InitAddress 127.0.0.1:1212
                SelectDB 0
                Username caddy
                Password <redacted>
                ConnWriteTimeout 5s
            }
        }
    }
}
mirrors.tnonline.net:443 {
    tls /etc/caddy/certs/mirrors.tnonline.net_cert.pem /etc/caddy/certs/mirrors.tnonline.net_privkey.pem
    log {
        output file /var/log/caddy/mirrors.tnonline.net.log {
            roll_disabled
        }
        format json
    }
    encode br zstd gzip
    @botz {
        header User-Agent *amazonbot*
    }
    redir @botz https://developer.amazon.com/support/amazonbot 401
    respond @botz 429
    
    #cache <-- temporarily disabled due to bug
    reverse_proxy h2c://mirrors.tnonline.net:400 {
        header_up Host {upstream_hostport}
    }
}

I am hoping we can come up with a basic configuration example for each of the requirements.