Vnx-rootfslxc

How to create a LXC Ubuntu root filesystem for VNX

Basic installation

Follow this procedure to create a Ubuntu based LXC root filesystem for VNX. The procedure has been tested with Ubuntu versions from 13.10 to 18.04.

• Create the rootfs with:

lxc-create -t ubuntu -n vnx_rootfs_lxc_ubuntu-18.04

Note1: The default username/password is ubuntu/ubuntu.
Note2: This method creates an image with the same architecture (32 or 64 bits) as the host. To create a 32 bits image in a 64 bits host, the only method known to work is to follow the procedure described in this page inside a KVM 32 bits virtual machine.

• Move the rootfs to VNX filesystems directory:

mv /var/lib/lxc/vnx_rootfs_lxc_ubuntu-18.04/ /usr/share/vnx/filesystems/

• If using Ubuntu 17.10 or newer (lxc version 2.1 or newer), convert the configuration file to old config format (VNX converts back to the newer format if needed when starting containers):

lxc.rootfs.path -> lxc.rootfs
lxc.uts.name -> lxc.utsname
lxc.net.0.type -> lxc.network.type
lxc.net.0.link -> lxc.network.link
lxc.net.0.flags -> lxc.network.flags
lxc.net.0.hwaddr -> lxc.network.hwaddr

• Edit the rootfs configuration file (/usr/share/vnx/filesystems/vnx_rootfs_lxc_ubuntu-16.04/config) to reflect the directory change:

lxc.rootfs = /usr/share/vnx/filesystems/vnx_rootfs_lxc_ubuntu-16.04/rootfs
lxc.mount  = /usr/share/vnx/filesystems/vnx_rootfs_lxc_ubuntu-16.04/fstab

• Create fstab file (if not created):

touch vnx_rootfs_lxc_ubuntu-16.04/fstab

• Start the new rootfs to configure it and install new software:

lxc-start -n vnx -F -f /usr/share/vnx/filesystems/vnx_rootfs_lxc_ubuntu-16.04/config

• Once the VM has started, make login (ubuntu/ubuntu) and:
• Add VNX user and change the passwords:

sudo adduser vnx
sudo adduser vnx sudo
sudo passwd root

• Update and install software:

sudo apt-get update
sudo apt-get dist-upgrade
sudo apt-get install aptsh openssh-server traceroute telnet nmap apache2 wget tcpdump net-tools ifupdown
update-rc.d -f apache2 remove   # to avoid automatic start
systemctl disable apache2       # in newer systems

• Change VM name in hosts and hostname files:

sudo vi /etc/hosts         # change name to vnx
sudo vi /etc/hostname      #     "

• Enable root access through textual consoles with:

echo "pts/0" >> /etc/securetty
echo "pts/1" >> /etc/securetty
echo "pts/2" >> /etc/securetty
echo "pts/3" >> /etc/securetty

• Important: edit /etc/network/interfaces and coment "inet dhcp" lines to avoid delays at startup. Besides, edit /etc/init/failsafe.conf and change all "sleep XX" commands to "sleep 1".
• Disable auto-upgrades if enabled:

sed -i -e 's/"1"/"0"/g' /etc/apt/apt.conf.d/20auto-upgrades

• Delete the "mesg n" command in root's .profile to avoid the nasty message "mesg: ttyname failed: No such device" when executing commands with lxc-attach:

sed -i '/^mesg n/d' /root/.profile

• Exit and login again with user vnx/xxxx to delete ubuntu user:

sudo deluser ubuntu

• Stop the VM with:

halt

• If you want to pack the root filesystem into a tar file, use the following command:

tar --numeric-owner -czpf vnx_rootfs_lxc_ubuntu-16.04-v025.tgz vnx_rootfs_lxc_ubuntu-16.04-v025

• Optionally, create a short link to the rootfs:

cd /usr/share/vnx/filesystems
ln -s vnx_rootfs_lxc_ubuntu-16.04 rootfs_lxc