Fetch Partition and pass ntpservers to metal-hammer

[majst01]

Once metal-stack/metal-api#571 is merged and a grpc endpoint to fetch the partition is implemented.

[robertvolkmann]

A server with an incorrect time may struggle to validate the TLS server certificate, preventing it from connecting to Pixie to retrieve the NTP servers. Therefore, we need to provide the NTP servers through DHCP.

option ntp-servers ip-address [, ip-address... ];

This option specifies a list of IP addresses indicating NTP (RFC 5905) servers available to the client. Servers should be listed in order of preference.

[majst01]

metal-hammer fetches the config from pixiecore with http, so time difference would not be an issue, but talking to metal-api can only happen if time is synced because this is a mTls connection.

We can of course configure ntp with the dhcp option, this must be done with ansible, it would also be nice if a partition config is automatically applied to the metal-hammer without the need of a ansible deployment.

It can be done both, initially with ansible, metal-hammer will get a ntp server from the dhcp server, if something else is configured in the partition, and pixiecore ask metal-api for dns and ntp server, then forward it to the metal-hammer.