[pve-devel] [RFC cluster/manager/network 0/6] Add support for DHCP servers to SDN

[DERUMIER, Alexandre]

Hi,

I think we should think how we want to attribute ips to the vms before
continue the implementation.

I think they are 2 models:

1)

- we want that dhcp server attribute itself ips && leases from the
subnets/ranges configured.

That mean that leases need to be shared across nodes.  (from the same
cluster maybe with /etc/pve tricks,   but in real world, it should also
works across multiple clusters, as it's not uncommon to shared subnets
in differents cluster, public network,...)

So we don't have that 2 differents vms starting on the same time on 2
differents cluster, receive the same ips. (so dhcp servers need to use
some kind of central lock,...)


2)

The other way (my preferred way), could be to use ipam. (where we
already have local ipam, or external ipams like netbox/phpipam for
sharing between multiple cluster).


The ip is reserved in ipam  (automatic find next free ip at vm creation
for example, or manually in the gui, or maybe at vm start if we want
ephemeral ip), then registered dns, 
and generated dhcp server config with mac-ip reserversation. (for dhcp
server config generation, it could be a daemon pooling the ipam
database change for example)

Like this, no need to handle lease sharing, so it can work with any
dhcp server.




What do you think about it ?


Le vendredi 08 septembre 2023 à 15:42 +0200, Stefan Hanreich a écrit :
> This patch series adds support for automatically deploying dnsmasq as
> a DHCP
> server to a simple SDN Zone.
> 
> While certainly not 100% polished on some ends (looking at restarting
> systemd
> services in particular), the general idea behind the mechanism shows.
> I wanted
> to gather some feedback on how I approached designing the plugins and
> the
> config regeneration process before comitting to this design by
> creating an API
> and UI around it.
> 
> For your testing convenience I've provided deb packages on our share:
>   /path/to/nasi/iso/packages/shan-sdn-dhcp
> 
> You need to install dnsmasq (and disable it afterwards):
> 
>   apt install dnsmasq && systemctl disable --now dnsmasq
> 
> 
> You can use the following example configuration for deploying a DHCP
> server in
> a SDN subnet:
> 
> /etc/pve/sdn/dhcp.cfg:
> 
>   dnsmasq: nat
> 
> 
> /etc/pve/sdn/zones.cfg:
> 
>   simple: DHCPNAT
>           ipam pve
> 
> 
> /etc/pve/sdn/vnets.cfg:
> 
>   vnet: dhcpnat
>           zone DHCPNAT
> 
> 
> /etc/pve/sdn/subnets.cfg:
> 
>   subnet: DHCPNAT-10.1.0.0-16
>           vnet dhcpnat
>           dhcp-dns-server 10.1.0.1
>           dhcp-range server=nat,start-address=10.1.0.100,end-
> address=10.1.0.200,lease-time=86400
>           dhcp-range server=nat,start-address=10.1.1.100,end-
> address=10.1.1.200,lease-time=86400,dns-server=10.1.0.2
>           gateway 10.1.0.1
>           snat 1
> 
> 
> Then apply the SDN configuration:
> 
>   pvesh set /cluster/sdn
> 
> 
> Be careful that after configuring dhcp-range you do not save the
> subnet config
> from the Web UI, since the dhcp-range line will vanish from the
> config.
> 
> 
> 
> pve-cluster:
> 
> Stefan Hanreich (1):
>   cluster files: add dhcp.cfg
> 
>  src/PVE/Cluster.pm  | 1 +
>  src/pmxcfs/status.c | 1 +
>  2 files changed, 2 insertions(+)
> 
> 
> pve-manager:
> 
> Stefan Hanreich (1):
>   sdn: regenerate DHCP config on reload
> 
>  PVE/API2/Network.pm | 1 +
>  1 file changed, 1 insertion(+)
> 
> 
> pve-network:
> 
> Stefan Hanreich (4):
>   sdn: dhcp: add abstract class for DHCP plugins
>   sdn: dhcp: subnet: add DHCP options to subnet configuration
>   sdn: dhcp: add DHCP plugin for dnsmasq
>   sdn: dhcp: regenerate config for DHCP servers on reload
> 
>  debian/control                      |   1 +
>  src/PVE/Network/SDN.pm              |  11 ++-
>  src/PVE/Network/SDN/Dhcp.pm         | 122
> ++++++++++++++++++++++++++++
>  src/PVE/Network/SDN/Dhcp/Dnsmasq.pm | 115 ++++++++++++++++++++++++++
>  src/PVE/Network/SDN/Dhcp/Makefile   |   8 ++
>  src/PVE/Network/SDN/Dhcp/Plugin.pm  |  76 +++++++++++++++++
>  src/PVE/Network/SDN/Makefile        |   4 +-
>  src/PVE/Network/SDN/SubnetPlugin.pm |  43 ++++++++++
>  8 files changed, 377 insertions(+), 3 deletions(-)
>  create mode 100644 src/PVE/Network/SDN/Dhcp.pm
>  create mode 100644 src/PVE/Network/SDN/Dhcp/Dnsmasq.pm
>  create mode 100644 src/PVE/Network/SDN/Dhcp/Makefile
>  create mode 100644 src/PVE/Network/SDN/Dhcp/Plugin.pm
> 
> 
> Summary over all repositories:
>   11 files changed, 380 insertions(+), 3 deletions(-)
> 
> --
> murpp v0.4.0
> 
> 
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