How To Upgrade FreeBSD Jail ( OS Level Virtualization )

Q. I've FreeBSD jail configured as explained in man pages using make world options. Now I've upgrade my base FreeBSD 7.0 system to FreeBSD 7 patch level 4. How do I upgrade my Jail (FreeBSD VPS) so that everything get updated inside jail?

A. The FreeBSD jail mechanism is an implementation of operating system-level virtualization that allows administrators to partition a FreeBSD-based computer system into several independent mini-systems called jails. FreeBSD jails offer security, ease of delegation and os level virtualization. To upgrade your jail using make world use the following commands.

Step # 1: Build world

Follow this guide to upgrade your running system. Once done type the following command to build world for jail:

WARNING! There are various ways of creating and upgrading jails. This method uses make world upgrade method as original jail was created using make build itself.

# JAIL=/path/to/jail
OR
# JAIL=/usr/home/jail/192.168.1.10
# cd /usr/src
# make buildworld DESTDIR=$JAIL
Please note that If you have just done make buildworld previously you can do make installworld and save the time.

Step # 2: Stop jail service

Type the following command to stop all jails:
# /etc/rc.d/jail stop

Step # 3: Upgrade jail

Type the following command to stop all jails:
# cd /usr/src
# make installworld DESTDIR=$JAIL
# mergemaster -i -C -D $JAIL
If you have multiple jail repeat above steps. You can also try something as follows:
# JPATHS="/jail/path1 /jail/path2 /jail/path3"
# for j in $JPATHS; make installworld DESTDIR=$j; done

Step # 4: Start all jails

Type the following command:
# /etc/rc.d/jail start
Make sure everything is running:
# jls
Try to connect to jail called www.example.com with 20 as jail id from host itself:
# jexec 20 sh
# hostname
# sockstat
Try to upgrade FreeBSD ports inside jail:
# portsnap fetch update
# portversion -l '<'
# portupgrade -a
Exit from jail and go back to host:
# exit