Unless otherwise stated, all commands presented on this page must be executed as root.
So, either run them as sudo <command>, or switch to root at the beginning by typing su.
apt-get install schroot
debootstrap is used to install a Debian base system(the new root), for the example below.
apt-get install debootstrap
Configuration file: /etc/schroot/schroot.conf
If you prefer separate configuration files, place them in /etc/schroot/chroot.d/.
A simple example that creates a chroot and installs <some-package> for an X Window environment. This is not the safest nor a standard way of setup. [REQUEST FOR EDIT: Please link to docs for a couple of the safe and standards methods]
Create root file system:
mkdir -p /srv/chroot/test debootstrap bullseye /srv/chroot/test
Make a file /etc/schroot/chroot.d/bullseye-test:
# schroot chroot definitions. # See schroot.conf(5) for complete documentation of the file format. # # Please take note that you should not add untrusted users to # root-groups, because they will essentially have full root access # to your system. They will only have root access inside the chroot, # but that's enough to cause malicious damage. # # The following lines are examples only. Uncomment and alter them to # customise schroot for your needs, or create a new entry from scratch. # [bullseye-test] description=Contains the SPICE program aliases=test type=directory directory=/srv/chroot/test users=jsmith root-groups=root profile=desktop personality=linux preserve-environment=true
Where jsmith is an underprivileged user.
schroot -c test
W: Failed to change to directory '/ ... is ok.
apt-get update && apt-get install <some-package> exit
As the user jsmith execute:
xhost + schroot -c test
From this point the <some-package> could be used...
xhost + SESH=$(schroot -c test -b) schroot -r -c $SESH schroot -e -c $SESH
For Faster Builds
Use of tmpfs overlay or use of eatmydata package may provide significant speedup on slow HDD. For example, on a system where lintian takes an hour to build, a tmpfs overlay may enable the completion of the same work in 21 minutes. (With new NVMe SSD, you may not see much difference.)
Follow the guide sbuild#Speeding_up_build_process.
To use tmpfs overlay, add the following line to each configuration file in /etc/schroot/chroot.d:
The two downsides of tmpfs are that it requires a fair amount of free RAM, and that the memory pressure can push desktop application to swap. On a related note, the use of swap is recommended when using tmpfs overlays, because if a build triggers the OOM killer then one's browser will almost certainly be the first to go. The use of tmpfs is also useful for the fast NVMe SSD system since it reduces writes and prolongs the life of SSD.
To use eatmydata package, install eatmydata package to each chroot and add the following line to each configuration file in /etc/schroot/chroot.d:
When you logout a schroot's session sometime it can happen that some processes keep busy the mount-point causing this error message:
~$ logout E: 10mount: rmdir: failed to remove '/var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a': Device or resource busy E: kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a: Chroot setup failed: stage=setup-stop
to retrive the PID you can take a piece of the name of the directory, says "d2c072e7" and look for in the /proc filesystem:
~$ grep -r d2c072e7 /proc/*/mountinfo /proc/3919/mountinfo:195 41 253:3 / /var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a rw,relatime shared:134 - ext4 /dev/mapper/ld0-lv2 rw,stripe=256,data=ordered /proc/3919/mountinfo:199 195 0:14 / /var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a/sys rw,nosuid,nodev,noexec,relatime shared:136 master:7 - sysfs sysfs rw /proc/3919/mountinfo:216 195 0:3 / /var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a/proc rw,nosuid,nodev,noexec,relatime shared:151 master:12 - proc proc rw /proc/3919/mountinfo:218 195 0:5 / /var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a/dev rw,relatime shared:153 master:2 - devtmpfs udev rw,size=10240k,nr_inodes=988768,mode=755 /proc/3919/mountinfo:223 195 0:15 / /var/lib/schroot/mount/kubuntu-d2c072e7-7e0c-4cfc-b48e-73defe8a4f0a/run rw,nosuid,relatime shared:158 master:5 - tmpfs tmpfs rw,size=1585940k,mode=755
Therefore "3919" is the PID to kill in order to remove the directory.
See Also :
SchrootPackaging - Packages stuck with Schroot
https://linuxgazette.net/150/kapil.html - Virtualizing without Virtualizing
other SystemVirtualization solutions