String checkHostname(String hostname) {
        if (isHosted) return hostname; // Done in node-repo instead

        if (doCheckIp) {
            BiConsumer<Level, String> logFunction = deployLogger::logApplicationPackage;
            // Give a warning if the host does not exist
            try {
                var inetAddr = java.net.InetAddress.getByName(hostname);
                String canonical = inetAddr.getCanonicalHostName();
                if (!hostname.equals(canonical)) {
                    logFunction.accept(Level.WARNING, "Host named '" + hostname + "' may not receive any config " +
                                                      "since it differs from its canonical hostname '" + canonical + "' (check DNS and /etc/hosts).");
                }
            } catch (UnknownHostException e) {
                logFunction.accept(Level.WARNING, "Unable to lookup IP address of host: " + hostname);
            }
        }
        return hostname;
    }
The parent node for all Host instances, and thus accessible
to enable services to get their Host.

@author gjoranv
config-model/src/main/java/com/yahoo/vespa/model/HostSystem.java