OVH: How to add Additional IP Addresses (IP Alias) on Ubuntu 16.04 / 18.04

Adding additional IP addresses in OVH is rather unconventional and the guide they point to in their mail is non-existent. The process, fortunately, is simple:

  1. ssh to the server as root
  2. cd /etc/systemd/network/
  3. vi *-default.network
  4. Add the new IP address after the original IPv4 Address
    DHCP=no
    Address=Main_IP/24
    Address=Failover_IP/32
  5. Save and close the file
  6. Reboot the server

You should now be able to ssh to the server using the new IP Address (which OVH likes to call Failover IP Address) in addition to the old one.

Repeat the process for any additional IP addresses.

Note: I have tested it on two different OVH Servers (in France & Canada) for Ubuntu 16.04 and Ubuntu 18.04.

LXD: How to easily apt update and upgrade all running LXD containers

It is easy to create large number of LXD / LXC containers as it consumes minimal resources. Coupled with btrfs, it consumes minimal hard-disk space also due to de-duplication built-in within btrfs file system. Soon you would find yourself spending a significant amount of time updating (sudo apt update) and upgrading (sudo apt -y upgrade) all these containers (don’t forget: sudo apt -y autoremove). Here is a simple bash-fu magic which you can run from host to update all the containers:
lxc -c ns --format csv ls|grep RUNNING|cut -f1 -d',' | xargs -I'{}' sh -c "echo Updating '{}';lxc exec '{}' -- apt -qq update;lxc exec '{}' -- apt -qq -y upgrade;lxc exec '{}' -- apt -qq -y autoremove"

The code has been tested on Ubuntu 16.04 but it is expected to work on any Ubuntu system starting from 16.04. For previous version(s) use apt-get instead of apt.