It looks like Zanie suggested HTTP_TIMEOUT. Do you mind changing to HTTP_TIMEOUT, and displaying the current value too? This is great!

Good point, I decided to use UV_HTTP_TIMEOUT for consitency with registry_client.rs first check (which seems to prefer UV_HTTP_TIMEOUT and HTTP_TIMEOUT last). I could also update that warn_user_once as part of this PR if we want to be fully consistent.

            let timeout = env::var("UV_HTTP_TIMEOUT").or_else(|_| env::var("UV_REQUEST_TIMEOUT")).or_else(|_| env::var("HTTP_TIMEOUT")).and_then(|value| {
                value.parse::<u64>()
                    .or_else(|_| {
                        // On parse error, warn and  use the default timeout
                        warn_user_once!("Ignoring invalid value from environment for UV_REQUEST_TIMEOUT. Expected integer number of seconds, got \"{value}\".");
                        Ok(default_timeout)
                    })
            }).unwrap_or(default_timeout);

I think UV_HTTP_TIMEOUT is good, it seems better not to recommend changing a value that other clients will respect unless you need to.

Can we say how long the timeout is currently though?

Added in 65a5c35 and 783a419. I didn't see reqwest allowing us to look at config.timeout, so I ended up exposing our timeout to the RegistryClient struct instead.