ezjail Flavour

About Flavours
ezjail provides a template system called "flavours." A flavour can be specified when creating an ezjail jail (-f flag), making it extremely easy to create similar jails over and over.

Flavours live in BASE_EZJAIL_DIR/flavours - the rest of this post will assume BASE_EZJAIL_DIR is /usr/jails and ezjail-admin version is 3.0.

Create A Flavour

$ cd /usr/jails/flavours
$ sudo cp -r example theusual
$ cd theusual/etc
$ sudo vi resolv.conf
$ cd ..

The above block copied the example directory to theusual and then created resolv.conf so the new jail knows the local nameserver.

Now to use it.

$ sudo ezjail-admin create -f theusual jail1 10.10.10.101
$ sudo ezjail-admin start jail1
$ sudo ezjail-admin console jail1
# telnet www.google.com 80

The above assumes network settings are correct and a firewall does not block out going port 80 traffic.

On the first start-up, the new jail will run ezjail.flavour, which is a shell script. This can be modified to add users, packages, start services, and so on. With a working network, hopefully setup with the above resolv.conf, packages can even be installed remotely.

The example ezjail.flavour, which was copied, looks for a pkg directory and tries to load packages from there.

$ cd /usr/jails/flavours/theusual
$ sudo mkdir pkg
$ sudo cp /some/dir/with/some_package.tbz pkg/

Upon initial start-up, the next jail created with this flavour will install the local package some_package. The example script also has examples for adding users, groups, and starting services.

A Full Example
The example flavour, provided by ezjail, has a few lines for adding groups, users, and packages. Below is a full example, with the few modifications clearly labeled. This is used to create an environment for Hadoop by installing java (in pkg directory), creating a hadoop user, and setting up and starting sshd.

#!/bin/sh
#

# Groups
#########
#
# You will probably start with some groups your users should be in

pw groupadd -q -n hadoop # -g 1004

# Users
########
#
# You might want to add some users. The password is to be provided in the
# encrypted form as found in /etc/master.passwd.
# The example password here is "admin"
# Refer to crypt(3) and pw(8) for more information

# add our hadoop user here
# user: hadoop, group: hadoop, uid: 110
pw useradd -n hadoop -u 110 -g hadoop -s /bin/sh -m -d /home/hadoop -c 'hadoop account'
mkdir -p /home/hadoop/.ssh
chmod 700 /home/hadoop/.ssh

echo -n 'NOTE: THIS WOULD BE SSH KEY' >> /home/hadoop/.ssh/authorized_keys2
chown -R hadoop:hadoop /home/hadoop

# Files
########
#
# You can now give files to users just created

# /usr/hadoop is where hadoop will live
tar -zxf /usr/hadoop/hadoop*tar.gz -C /usr/hadoop/
rm /usr/hadoop/hadoop-*.tar.gz
chown -R hadoop:hadoop /usr/hadoop

# Packages
###########
#
# Install all packages previously put to /pkg
# Remove package files afterwards

# load the staged packages
[ -d /pkg ] && PACKAGESITE=file:// pkg_add -r /pkg/*
rm -rf /pkg

# Postinstall
##############
#
# Your own stuff here, for example set login shells that were only
# installed just before.
hname=`uname -n`
# sshd
echo "ListenAddress $hname" >> /etc/ssh/sshd_config
echo 'sshd_enable="YES"' >> /etc/rc.conf
/etc/rc.d/sshd start