ENG-27785: allow port-only for -m, require host for -b

[benjaminballard]

The previous ENG-27785 change setting the default value to "12223" for the -m metrics bind address caused meshmonitor to crash with a port already in use exception, unless you provided -m "0.0.0.0:12223" which I've used successfully as a workaround to get data to Prometheus. Now I'm circling back to fix this.

PicoCLI handles the CLI argument parsing, but in the case of the -b and -m options, and the parameter (optional list of hostnames), since these are mapped to InetSocketAddress attributes, PicoCLI does not provide a built-in converter to this type. This project has used a custom converter class to handle parsing these inputs to InetSocketAddress output, but it treated the absence of ":" as a hostname-only address, not a port-only address. So for -m 12223, rather than getting that port with the wildcard host, it converted the integer 12223 to the IP address "0.0.47.191" and tacked on the default port 12222 (which should only be used for -b, not for -m). Hence the metrics http server came up trying to use port 12222 which was already in use by meshmonitor.

I've created a new separate converter for -m, which allows port-only, and handles IPv4 and IPv6 hosts if provided.

I could have left the existing converter alone for -b and the parameter list, but it only works if the FQDN or ip address is provided, so setting -b and providing a hostname should be required.

[dave-voltdb]

wow!

[dave-voltdb]

Does this mean you only listen on a single interface?

[benjaminballard]

requiresHostname = true means the user must provide some sort of hostname. It could be [:::] or 0.0.0.0, or locahost, but it can't be empty.