T2958: Refactor DHCP-server systemd unit and lease

[sever-sever]

Change Summary

Render isc-dhcp-server systemd unit from configuration

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T2958

Component(s) name

dhcp-server

Proposed changes

How to test

set service dhcp-server shared-network-name NET authoritative
set service dhcp-server shared-network-name NET subnet 192.0.2.0/24 range RANG01 start 192.0.2.10
set service dhcp-server shared-network-name NET subnet 192.0.2.0/24 range RANG01 stop 192.0.2.130
set service dhcp-server shared-network-name NET subnet 192.0.2.0/24 default-router 192.0.2.1

Check leases in /run directory

vyos@vyos:~$ cat /run/dhcp-server/dhcpd.leases
# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.4.3-P1

# authoring-byte-order entry is generated, DO NOT DELETE
authoring-byte-order little-endian;

server-duid "\000\001\000\001,\200{6RT\000\311\275\205";

lease 192.0.2.10 {
  starts 2 2023/08/29 09:49:01;
  ends 3 2023/08/30 09:49:01;
  cltt 2 2023/08/29 09:49:01;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 52:54:00:92:35:5d;
  set shared-networkname = "NET";
  client-hostname "r1";
}
lease 192.0.2.11 {
  starts 2 2023/08/29 09:55:09;
  ends 3 2023/08/30 09:55:09;
  cltt 2 2023/08/29 09:55:09;
  binding state active;
  next binding state free;
  rewind binding state free;
  hardware ethernet 52:54:00:04:33:2b;
  set shared-networkname = "NET";
  client-hostname "r14";
}

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[sever-sever]

Or we can just create the “/config” directory

[sarthurdev]

Or we can just create the “/config” directory

I suppose this would be best. No further proceessing needed in conf script. Though a warning might be needed to state the contents is not retained.

[dmbaturin]

I like the dehardcoding of the file name, but I also disagree with adding a fixup. The live CD environment should not be different from the installed environment, we need to find out why /config is not created and create it.

[jestabro]

I am looking into some related matters, regarding /config and live-boot; I'll add an update should it reveal anything useful ...

[sever-sever]

Another solution vyos/vyos-build#383

[c-po]

I'm in favour of vyos/vyos-build#383

[sarthurdev]

With vyos/vyos-build#383 merged, suppose this can be closed?

[sever-sever]

With vyos/vyos-build#383 merged, suppose this can be closed?

We agree to rewrite part of this and delete lease related configuration, other looks good.
Will do soon.

[sarthurdev]

Will this cause any problems with the lease file no longer being persistent across reboots?

[sever-sever]

Will this cause any problems with the lease file no longer being persistent across reboots?

Sure, there should be /config/dhcpd.leases
It seems I deleted the wrong path variable for leases :)
Fix #2203