Reloading of config without restart.

[partim]

Ideally, Routinator would gain a reload command (via SIGHUP?) that would cause it to reload the configuration and apply it while keeping all open RTR connections and the current dataset.

However, there are a few issues around that. Specifically, an instance may have dropped privileges and may not even be able to access files or bind to sockets any more. So we would need specific rules as to which configuration option are hot-changeable and what happens if reloading fails for one or many parts.

A use case specifically mentioned is reloading of TLS keys and certificates (#977). In this case, the instance may not even get to the key files anymore – it is not unlikely that Routinator is running as a normal user and the key is only accessible to root.