Reserving IP for bridge networks

LXD Support
1

Hi all,

My bridge looks like below.

name: lxdbr0
description: ""
type: bridge
managed: true
status: Created
config:
  ipv4.address: 10.152.22.1/24
  ipv4.nat: "true"
  ipv6.address: none

1 Where do lxd keeps track of IPs released to instances/containers? Is there some dhcp server kind of thingy? I wanted to crated HA k8s on three machine containers using kube-VIP. So this needs IP (for virtual IP purposes) to be reserved for HA in k8s. This IP has to be part of same SM as instances.

Lets say I want to reserve IP 10.152.22.254, 253 for HA purpose. how do I do that? Once reserved these IPs should not be assinged to any VMs/instances created later.

2 With /24 254 IPs are possible. Is there any way I cand modify this subnet?

edit - for 2, looks like editing lxc network edit lxdbr0 and changing values of ipv4.address is suffice for SM change. Only thing is - you need delete existing instances to get IP from new range

Mak

2

ps -ef | grep lxd tells me this

lxd 71964 0.0 0.0 10500 4144 ? Ss 17:18 0:00 dnsmasq --keep-in-foreground --strict-order --bind-interfaces --except-interface=lo --pid-file= --no-ping --interface=lxdbr0 --dhcp-rapid-commit --no-negcache --quiet-dhcp --quiet-dhcp6 --quiet-ra --listen-address=10.2.0.1 --dhcp-no-override --dhcp-authoritative --dhcp-leasefile=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.leases --dhcp-hostsfile=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.hosts --dhcp-range 10.2.0.2,10.2.15.254,1h -s lxd --interface-name _gateway.lxd,lxdbr0 -S /lxd/ --conf-file=/var/snap/lxd/common/lxd/networks/lxdbr0/dnsmasq.raw -u lxd -g lxd

So I went to /var/snap/lxd/common/lxd/networks/lxdbr0/ and there dnsmsq.pid file have thse arguments. Tried editing the dhcp-range argument on this file and bounced lxd service from snap.

Futile

3

For bridge networks LXD uses dnsmasq.

You can specify the ranges of IPs that LXD will allocate dynamic addresses from by specifying:

https://documentation.ubuntu.com/lxd/en/latest/reference/network_bridge/#network-bridge-network-conf:ipv4.dhcp.ranges

E.g.

lxc network set lxdbr0 ipv4.dhcp.ranges=192.0.2.10-192.0.2.20

Anything outside of the range can then be used freely.

2 Likes
4

Thanks a lot for help.

1 Like