Hub Template Debian 11 cloud init network configuration

vmpr

Hi Team! thanks for your great work
I have a question regarding the debian11 hub cloud-init template. maybe @fohdeesha is the right person?

I am using this network configuration for deployment:

network:
  version: 1
  config:
    - type: physical
      name: eth0
      subnets:
        - type: static
          address: 172.16.232.93/26
          gateway: 172.16.232.65
          dns_nameservers:
            - 172.16.232.65
          dns_search:
            - xx.xxxxxx.xx

The Machine boots and gets an IP from DHCP and installs how it should, but it never changes to the configured IP address until I reboot the machine, but then it comes up with two IP-addresses:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether aa:90:ca:c4:15:c2 brd ff:ff:ff:ff:ff:ff
    inet 172.16.232.93/26 brd 172.16.232.127 scope global eth0
       valid_lft forever preferred_lft forever
    inet 172.16.232.121/26 brd 172.16.232.127 scope global secondary dynamic eth0
       valid_lft 541041sec preferred_lft 541041sec
    inet6 fe80::a890:caff:fec4:15c2/64 scope link
       valid_lft forever preferred_lft forever

the one I configured with the YAML and also the DHCP IP address from the first boot.

I can see these configurations:
cloud-init network configuration file from YAML config

root@XXX:~ cat /etc/network/interfaces.d/50-cloud-init
# This file is generated from information provided by the datasource.  Changes
# to it will not persist across an instance reboot.  To disable cloud-init's
# network configuration capabilities, write a file
# /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
# network: {config: disabled}
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet static
    address 172.16.232.93/26
    dns-nameservers 172.16.232.65
    dns-search qa.oneserv.de
    gateway 172.16.232.65

Debian standard network config file with DHCP enabled:

root@XXX:~ cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).

source /etc/network/interfaces.d/*

# The loopback network interface
auto lo
iface lo inet loopback

# The primary network interface
allow-hotplug eth0
iface eth0 inet dhcp

Does anyone know what I have to do to get rid off the DHCP assigned IP address and how I can apply the configured network config instantly without having the DHCP assigned one or without rebooting after the installation?

And what is the default user password for the debian or root user? i deploy keys so I can access the machine normally but if I have problems with network or sshd then I would like to login via xoa-console but don't have a pw

cheers, Ringo

olivierlambert

Question for @fohdeesha

fohdeesha

@vmpr Hi, this is one of cloud-inits many "features" - on debian and debian-like distros, it does not overwrite /etc/network/interfaces - it appends the existing config with a file placed under /etc/network/interfaces.d/ as you noticed - this is cloud-inits design choice. So when Debian's default /etc/network/interfaces file has dhcp configured on eth0, it's going to pull a DHCP address. There's two ways around this. One, you can remove the interface config inside of /etc/network/interfaces - I thought about this briefly when creating the hub templates - then debian would not have its own DHCP address added to your static config. The problem though is users who do not provide their own network config during spin up (which is about 90% of our users) will have a VM spin up with no network config or address at all, which obviously isn't an option.

The second option is using cloud-inits ability to run commands after spin-up, and use it to run sed or similar to remove the dhcp config out of the /etc/network/interfaces file, then restart the networking service. If you google around you'll find some suggestions about this and the syntax to use (I'm not an expert here). https://cloudinit.readthedocs.io/en/latest/topics/modules.html#runcmd

As for it taking a reboot for the static IP to be applied, I never experienced that so I can't say what's going on there. As for the default password, there is no passwords for any users on the templates by default for security reasons. You must use a key, or use the runcmd cloud-init param above to run something like echo 'root:mypass' | chpasswd after the first boot to set a password

vmpr

@fohdeesha thanks for the information, I've added the following to my cloud-init template:

runcmd:
  # disable dhcp for eth0
  - [ sh, -c, sed -e '/iface eth0 inet dhcp/s/^/#/g' -i /etc/network/interfaces ]

at the end of the installation I have a reboot of the machine anyway so I don't restart the network in between:

power_state:
 delay: "+2" # minutes
 mode: reboot
 message: rebooting system after cloud-init configurations are finished
 timeout: 120 # seconds

cheers and keep up the good work!
Ringo

fohdeesha

@vmpr Great work and example!