Ubuntu 14.04 and LXC containers

Ubuntu releases after 10.04 LTS do no longer provide unfs3. Unfs3 is useful when one want to setup a fog server in a container with OpenVZ or LXC. Nfs kernel server cannot run in these containers.

Here's how to setup a FOG server in a LXC container.

Prerequisites

• A computer (physical or virtual) running Ubuntu 14.04 Server, may or may not using LVM, with available space in at least one volume group

Network setup on the LXC host

Setup a bridge on the computer, with at least one ethernet interface attached to it.

apt-get install bridge-utils

edit the file /etc/network/interfaces and add the following lines. Please ensure you're not using a SSH session, because you may lose your connection !

Add the following lines : auto br0 iface br0 inet static address 192.168.1.2 netmask 255.255.255.0 gateway 192.168.1.1 bridge_ports eth0 bridge_fd 0 bridge_maxwait 0

Reboot the computer and check network connectivity

LXC container creation

First, create a LXC container running Ubuntu. The version is the latest LTS version available at the moment of creating the container

 lxc-create -n server-fog -t ubuntu -B lvm --vgname vg --lvname lv-server-fog --fssize=10G --fstype=ext4

This will create a logical volume lv-server-fog in the volume group vg0, with a 10GB ext4 filesystem. The container wil be named server-fog. At the end of the process, the system will give you a login and a password.

Edit the file /var/lib/lxc/server-fog/config and setup networking for the container :

 lxc.network.link = br0
 lxc.network.ipv4 = 192.168.1.3
 lxc.network.gateway = 192.168.1.1

start your container

 lxc-start -n server-fog -F

login with the credentials given earlier, and change the password ! If needed, you have to shutdown the container to go back to the host's console

 sudo init 0

To run the container non interactively, use the following command

 lxc-start -d -n server-fog

To use a terminal in the container :

 lxc-console -n server-fog

You may exit the container at any time using the following keys (do not forget to logout first, because this will NOT logout any user in the container) :

 CTRL+A, Q

In the container you have to download, compile and install unfs3 from sources.

• Download unfs3
• decompress the archive : tar zxf unfs3-0.9.22.tar.gz
• apt-get install build-essential make flex bison
• cd unfs3-0.9.22
• ./configure
• make
• make install
• make install-init
• edit /etc/init.d/unfsd and replace the occurence of /usr/sbin/unfsd with /usr/local/sbin/unfsd
• /etc/init.d/unfsd start
• check unfsd is running : ps -ef | grep unfsd
• if it runs, then run update-rc.d unfsd defaults

Install and configure fog as usual.

If you want to setup a separate volume for your images :

• assuming you want to use a logical volume (LVM) /dev/vg0/lv with a ext3 filesystem :
• run your container and move all files located in /images into an other location (/root/images-bak), including the hidden file /images/.mntcheck
• from the lxc host, open /var/lib/your-container/fstab and add the following line : /dev/vg0/lv images ext3 defaults 0 0
• restart the container, and check the nex volume is available : run mount without any argument.
• If the LVM volume has been successfully mounted, move back the files backed up in /root/images-bak. Note there is no slash before images.
• chmod 777 /images

Once your setup is up and running, do not forget to enable autostart of your container :

edit /var/lib/lxc/server-fog/config :

 lxc.start.auto = 1