mkjail can be used on FreeBSD to create new jails, keep them updated, and upgrade to a new release.

mkjail requires the use of ZFS will create each new jail in a separate filesystem.

mkjail is not a jail manager. Jails are configured via /etc/jail.conf and started/stopped via service jail start foo.

This work was created by Mark Felder who gave Dan Langille the sourcecode. Dan uploaded it first to his private git server, then to his GitHub account.

Shortly thereafter, https://github.com/mkjail/mkjail was created.

When running getrelease, I advise not specifying the -s parameter. Just let the mkjail.conf configuration file do its work.

This script assumes you're using ZFS. mkjail should be in the same root dir as everything else you create below. (yeah, i know...)

1. clone this repo

2. make a flavour if you want

    # mkdir -p /var/db/mkjail/flavours/default/etc
    # vi /var/db/mkjail/flavours/default/etc/resolv.conf
    

3. make your jail. The -j is the name you want your jail to be.

    # ./src/bin/mkjail create -v 10.3-RELEASE -j testjail -f default
    Creating zroot/jails/testjail...
    Extracting base into /zroot/jails/testjail...
    Extracting doc into /zroot/jails/testjail...
    Extracting games into /zroot/jails/testjail...
    Extracting lib32 into /zroot/jails/testjail...
    Copying in our configs...
    
    Now put something like the following in /etc/jail.conf:
    
    exec.start = "/bin/sh /etc/rc";
    exec.stop = "/bin/sh /etc/rc.shutdown jail";
    exec.clean;
    mount.devfs;
    path = /zroot/jails/$name;
    
    testjail {
        host.hostname = "testjail";
        ip4.addr = 172.16.1.122;
        ip6.addr = 2602:100:4475:7e4e::2;
    }
    
    and then you can start the jail like so:
    
    # service jail start testjail
    

4. Put the recommendation into your /etc/jail.conf:

    sysrc jail_enable=YES
    

5. Then issue this command:

    service jail start testjail
    

Have fun.