14 KiB
jaildk - a FreeBSD jail development kit
This is the README for the FreeBSD jail utility jaildk. It can be
used to build, update, manage and run jails in a versioned environment.
Every jail consists of layers of directories mounted on top of each other using nullfs mounts. Some of them can be shared among jails, some are versioned. By using shared and versioned layers of mounts it is easy to update jails in a new version while the current version is still running, you can switch back to an older version of a jail.
Most of the layers are mounted read-only for security reasons.
Let's take a look at the layers of a typical running jail built with jaildk:
1 /jail/base/12.1-RELEASE-p10 /jail/run/db read-only
2 /dev/md12 /jail/run/db/tmp nosuid
3 devfs /jail/run/db/dev multilabel
4 /jail/log/db-20201026 /jail/run/db/var/log
5 /jail/appl/db-20201026 /jail/run/db/usr/local read-only
6 /jail/etc/db/etc-20201026 /jail/run/db/etc read-only
7 /jail/etc/db/local-etc-20201026 /jail/run/db/usr/local/etc read-only
8 /jail/etc/db/cron-20201026 /jail/run/db/var/cron
9 /jail/home/db/root-20201026 /jail/run/db/root
10 /jail/data/db/mysql-20201026 /jail/run/db/usr/local/data/mysql
11 /backup/db /jail/run/db/var/backups
|
+--- root of the jail
As can be easily deduced this is a database jail with the following layers:
- base layer: This is basically the same as a FreeBSD base, which
contains all biinaries, libraries and other files required to boot
up a FreeBSD system. Our base doesn't contain a kernel by default,
but you could add one, required if you want to use the ports
collection and compile
lsofyourself.
This particular base is based on 12.1-RELEASE-p10, that is, I created it while I had this release installed and running on the host system. - tmp layer: Just a ramdisk for
/tmp, the size can be tuned. - dev layer: Contains /dev/null and friends, required by every jail.
- log layer: Here we have our first versioned layer for
/var/log. Notise how all other layers are using the same version, this is done by purpose (but can be changed if you like). The version is a jail variable (see below) which is being used for all layers. - application layer: As you know if you're using FreeBSD, any
additional software, wether installed from a port or as package,
will be installed to
/usr/local. In our case it contains the mysql server software, bash and a couple of supporting utilities. It is being mounted read-only, so no new software can be installed in the running jail. This might sound annoying at first, because you can't just install stuff inside the jail anytime. But it forces you to work more disciplined. Once a jail has been completely built you can be sure, all components match with each other. Read below how to install or update software in a jail. - /etc layer: this just contains the normal etc, it is basically
a stripped copy of the host
/etc. We do not use it at all inside a jail, but it's required nontheless. There are some exceptions however, like/etc/resolv.conf. - /usr/local/etc layer: This is the place we configure all aspects of the jail, all configs reside here (like in our case the mysql config). It is also being mounted read-only, just like the etc layer.
- cron layer: A writable mount for the crontabs of users inside
the jail. That way one can modify crontabs with
crontab -e. However, if you don't want or need this, just remove the layer and add cronjobs to/etc/crontab. - /root layer: most of the administrative work inside a jail must
be done as the root user and it would be a pity not to have a
writable history. So,
/rootis mounted writable to add more comfort. - a data layer: A versioned data layer which contains the binary data of our mysql server. This is very jail specific and you have to add such layers yourself. Variants of such a layer include the document root of a webserver or the repositories of a git server.
- backup layer: Another custom layer, here we've mounted a global backup directory of our host which contains all backups.
All layers are configured in a mount.conf file specific for each
jail. The one for this jail looks like this:
base/$base $name nullfs ro
md $name/tmp mfs rw,nosuid,async 500m 1777
dev $name/dev devfs
log/$name-$version $name/var/log nullfs rw
appl/db-$version $name/usr/local nullfs ro
etc/$name/etc-$version $name/etc nullfs ro
etc/$name/local-etc-$version $name/usr/local/etc nullfs ro
etc/$name/cron-$version $name/var/cron nullfs rw
home/$name/root-$version $name/root nullfs rw
data/$name/mysql-$version $name/usr/local/data/mysql nullfs rw
/backup/db $name/var/backups nullfs rw
Now, as you can see, we're using variables here. Those are defined in
the jail.conf (not to be confused with /etc/jail.conf on the
host!):
name=db
version=20201026
base=12.1-RELEASE-p10
You might wonder how the other aspects of a jail are configured like
ip addresses, routing, jail parameters, sysctls etc. Well, that's
beyond the purpose of jaildk. You just use the standard FreeBSD
mechanism for these things, that is /ect/rc.conf, /etc/jail.conf,
service jail ..., jexec, etc. However, jaildk provides some
handy wrappers to make live easier.
For an overview of the provided commands, here's the usage screen:
Usage: jaildk <command> <mode-args>
Building Jails:
base - build a new base
build - install a build chroot of a jail
create - create a new jail from a template
clone - clone an existing jail or jail version
fetch - fetch current port collection
Installing Jails:
install - install a jail (prepare mounts, devfs etc)
uninstall - uninstall a jail
remove - remove a jail or a jail version
reinstall - stop, remove, install and start a jail
Maintaining Jails:
start - start a jail
stop - stop a jail
restart - restart a jail
status - display a jail's status
rc - execute an rc-script inside a jail
Managing Jails:
login - login into a jail (also available as separate command)
blogin - chroot into a build jail (dito)
Transferring Jails:
freeze - freeze (build an image of) a jail
thaw - thaw (install) an image of a jail somewhere else
Run the <command> without arguments to get usage help about the command.
Installation
Execute the following command:
./jaildk setup <directory>
This will create the directory structure required for the tool install the tool itself, create a template jail and build a base directory.
Basic usage
Let's say you installed jaildk into /jail and you want to create a
new jail with the name 'myjail' and the ip address '172.16.1.1'.
The following steps need to be done:
Configure /etc/jail.conf
Create the file /etc/jail.conf with the following innitial contents:
* {
exec.start = "/bin/sh /etc/rc";
exec.stop = "/bin/sh /etc/rc.shutdown";
allow.raw_sockets = "false";
sysvmsg = "new";
sysvsem = "new";
sysvshm = "new";
host.hostname = $name;
path = "/jail/run/$name";
exec.prestart = "/jail/bin/jaildk install $name start";
exec.clean = "true";
}
myjail {
ip4.addr = "172.16.1.1";
}
Refer to jail(8) for more possible settings.
Configure /etc/rc.conf
Next add the following lines to your /etc/rc.conf:
ifconfig_em0_alias0="inet 172.16.1.1/32"
jail_enable="YES"
You may need to replace the interface name em0 with the one in use on your system.
You might need to restart the interface to apply the alias: /etc/rc.d/netif restart.
Create the jail
# jaildk create myjail
- cpdup -x /jail/log/.template-20201106 /jail/test/log/myjail-20201106
- cpdup -x /jail/home/.template/root-20201106 /jail/test/home/myjail/root-20201106
- cpdup -x /jail/etc/.template/etc-20201106 /jail/test/etc/myjail/etc-20201106
- cpdup -x /jail/etc/.template/local-etc-20201106 /jail/test/etc/myjail/local-etc-20201106
/jail/data/.template/www doesn't exist, ignored
/jail/data/.template/spool doesn't exist, ignored
- cp -pRp /jail/etc/.template/mount.conf /jail/test/etc/.template/ports.conf /jail/test/etc/.template/mtree.conf /jail/test/etc/myjail/
cp: /jail/etc/.template/ports.conf: No such file or directory
Creating /jail/etc/.template/jail.conf
Creating run and build dirs
- mkdir -p /jail/run/myjail
- mkdir -p /jail/build/myjail
DONE.
Consider adding the jail myjail to /etc/jail.conf!
To mount the build chroot of the new jail, execute:
jaildk build myjail
To login into the build chroot
jaildk blogin myjail
To mount the production chroot of the new jail, execute:
jaildk install myjail
To login into the build chroot
jaildk login myjail
To start the jail, execute:
jaildk start myjail
Mount the build chroot of the jail
# jaildk build myjail
Installing jail myjail
mount - mount -t nullfs -o rw /jail/base/12.1-RELEASE-p10 /jail/build/myjail
mount - mdmfs -o rw,nosuid,async -s 128m -p 1777 md /jail/build/myjail/tmp
mount - mount -t devfs dev /jail/build/myjail/dev
mount - mount -t nullfs -o rw /jail/log/myjail-20201106 /jail/build/myjail/var/log
mount - mount -t nullfs -o rw /jail/appl/default-20201106 /jail/build/myjail/usr/local
mount - mount -t nullfs -o rw /jail/etc/myjail/etc-20201106 /jail/build/myjail/etc
mount - mount -t nullfs -o rw /jail/etc/myjail/local-etc-20201106 /jail/build/myjail/usr/local/etc
mount - mount -t nullfs -o rw /jail/home/myjail/root-20201106 /jail/build/myjail/root
Chroot into the build dir and install software
jaildk blogin myjail
pkg install bash nginx curl ...
vi /usr/local/etc/rc.conf
vi /usr/local/etc/nginx/nginx.conf
Since the build chroot is writable you can install packages and configure everything as needed.
Using the ports collection
There might be cases when using pre build binary packages are not your thing. In such a case you want to use the FreeBSD Ports Collection.
jaildk supports this, here are the steps required:
Create a buildbase
A normal base directory cannot be used with the ports collection because jaildk removes libraries and binaries for security reasons from normal bases. To create a build base, execute:
jaildk base -b 12-RELEASE-build -w
Next, add the following entry to the configuration of you jail. To
stay with our example, edit /jail/etc/myjail/jail.conf and add:
buildbase=12-RELEASE-build
Then install the build jail as usual:
jaildk build myjail
Install the current ports collection:
jaildk fetch
In case the ports version created does not match the version of your
jail, you need to configure the different ports version in your jail
config /jail/etc/myjail/jail.conf like this:
ports=20201127
Now you can enter the build jail and install ports the traditional way:
jaildk blogin myjail
cd /usr/ports/shells/bash
make config-recursive install clean
When done, install and start the jail
# jaildk install myjail
Installing jail myjail
mount - mount -t nullfs -o ro /jail/base/12.1-RELEASE-p10 /jail/run/myjail
mount - mdmfs -o rw,nosuid,async -s 128m -p 1777 md /jail/run/myjail/tmp
mount - mount -t devfs dev /jail/run/myjail/dev
mount - mount -t nullfs -o rw /jail/log/myjail-20201106 /jail/run/myjail/var/log
mount - mount -t nullfs -o ro /jail/appl/default-20201106 /jail/run/myjail/usr/local
mount - mount -t nullfs -o ro /jail/etc/myjail/etc-20201106 /jail/run/myjail/etc
mount - mount -t nullfs -o ro /jail/etc/myjail/local-etc-20201106 /jail/run/myjail/usr/local/etc
mount - mount -t nullfs -o rw /jail/home/myjail/root-20201106 /jail/run/myjail/root
# jaildk start myjail
Jail myjail start:
Starting jails: myjail.
# jaildk startus myjail
Jail scipown status:
JID IP Address Hostname Path
myjail 172.16.1.1 myjail /jail/run/myjail
Jail myjail rc status:
syslogd is running as pid 28180.
cron is running as pid 52130.
php_fpm is running as pid 45558.
nginx is running as pid 63975.
===> fcgiwrap profile: mediawiki
fcgiwrap is running as pid 37682.
Login into the running jail for administration
# jaildk login myjail
You can use this to login into a database or execute commands inside the jail.
Updating a jail
The very first thing to do is to update the host system using freebsd-update.
Next create a new base version:
jaildk base -b `uname -r`
Now you can create clone of your jail with a new version:
jaildk clone -s myjail -d myjail -o 20201106 -n 20210422
Mount the build chroot for the new version:
jaildk build myjail start -b `uname -r` -v 20210422
And finally chroot into the new jail and update it:
jaildk blogin myjail
pkg update
...
The last step is to remove the current running jail, change the version in etc/myjail.conf, install and start the new version.
If there's anything wrong you can always go back to the previous version using the above steps.
Getting help
Although I'm happy to hear from jaildk users in private email, that's the best way for me to forget to do something.
In order to report a bug, unexpected behavior, feature requests or to submit a patch, please open an issue on github: https://github.com/TLINDEN/jaildk/issues.
Copyright and license
This software is licensed under the BSD license.
Authors
T.v.Dein F.Sass (Culsu)