HOWTO: Make a chroot'ed CentOS

Unfortunately there is no anything similar to debbotstrap package for RPM based distros in Gentoo, so some sort of manual work is inevitable.

Ok, lets go!

First of all we need rpm and yum programs to be installed (yeah, you can emerge them). Then we can initialize RPMs database (I’ll do my chroot environment in the /storage/schroot/centos-6.5):

$ mkdir -p /storage/schroot/centos-6.5
$ rpm --root=/storage/schroot/centos-6.5 --rebuilddb

This will add an empty database to /storage/schroot/centos-6.5/var/lib/rpm. To enforce yum to work we have to install some configuration files for it. The easiest way to get them for your desired distro is to install centos-release package.

$ wget http://mirror.centos.org/centos/6.5/os/x86_64/Packages/centos-release-6-5.el6.centos.11.1.x86_64.rpm
 <skip details>
$ rpm --root=/storage/schroot/centos-6.5 --nodeps -i centos-release-6-5.el6.centos.11.1.x86_64.rpm
warning: Generating 12 missing index(es), please wait...
warning: centos-release-6-5.el6.centos.11.1.x86_64.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
$ rm centos-release-6-5.el6.centos.11.1.x86_64.rpm

This will install repository configuration files to ${chroot}/etc/yum.repos.d/. Edit that files according your needs: personally I want some extra repositories to be enabled in CentOS-Base.repo. Also yum wants to check RPM package signature, so here is few options to deal with:

make a symbolic link:

  $ ln -s /storage/schroot/centos-6.5/etc/pki /etc/pki

… or disable signature checking (temporarily) in CentOS-Base.repo config file

TODO

Better to write a ebuild w/ CentOS keyring keys, just like Debian/Ubuntu has (I’ve seen it in some repo).

Now we can do the next step – install a minimal base system:

$ yum --installroot=/storage/schroot/centos-6.5 update
base                                                  | 3.7 kB  00:00:00
centosplus                                            | 3.4 kB  00:00:00
contrib                                               | 2.9 kB  00:00:00
extras                                                | 3.4 kB  00:00:00
updates                                               | 3.4 kB  00:00:00
(1/5): contrib/primary_db                             | 1.2 kB  00:00:00
(2/5): base/primary_db                                | 4.4 MB  00:00:01
(3/5): centosplus/primary_db                          | 1.5 MB  00:00:01
(4/5): extras/primary_db                              |  19 kB  00:00:03
(5/5): updates/primary_db                             | 3.2 MB  00:00:04
Resolving Dependencies
--> Running transaction check
---> Package centos-release.x86_64 0:6-5.el6.centos.11.1 will be updated
---> Package centos-release.x86_64 0:6-5.el6.centos.11.2 will be an update
--> Finished Dependency Resolution

Dependencies Resolved

=======================================================================
 Package              Arch     Version              Repository    Size
=======================================================================
Updating:
 centos-release       x86_64   6-5.el6.centos.11.2  updates       20 k

Transaction Summary
=======================================================================
Upgrade  1 Package

Total download size: 20 k
Is this ok [y/N]: y
Downloading packages:
warning: /storage/schroot/centos-6.5/var/cache/yum/updates/packages/centos-release-6-5.el6.centos.11.2.x86_64.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Public key for centos-release-6-5.el6.centos.11.2.x86_64.rpm is not installed
centos-release-6-5.el6.centos.11.2.x86_64.rpm                                                                                   |  20 kB  00:00:00
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
Importing GPG key 0xC105B9DE:
 Userid     : "CentOS-6 Key (CentOS 6 Official Signing Key) <centos-6-key@centos.org>"
 Fingerprint: c1da c52d 1664 e8a4 386d ba43 0946 fca2 c105 b9de
 Package    : centos-release-6-5.el6.centos.11.1.x86_64 (installed)
 From       : /etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-6
Is this ok [y/N]: y
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Updating   : centos-release-6-5.el6.centos.11.2.x86_64            1/2
  Cleanup    : centos-release-6-5.el6.centos.11.1.x86_64            2/2
  Verifying  : centos-release-6-5.el6.centos.11.2.x86_64            1/2
  Verifying  : centos-release-6-5.el6.centos.11.1.x86_64            2/2

Updated:
  centos-release.x86_64 0:6-5.el6.centos.11.2

Complete!

$ yum --installroot=/storage/schroot/centos-6.5 install -y yum
<a lot of messages skipped>

The last command brings me 91 packages… Unfortunately Gentoo has next versions of rpm and yum, so “native” CentOS can’t understand the database. So, the rest installs better to do from inside a chrooted environment, but clean (yep, again) the RPMs database.

zaufi@gentop〉~〉 build-chroot
1) chroot:centos-6.5
#? 1
[schroot] password for builder:
-bash: mesg: command not found
(centos-6.5)builder@gentop:~$ su
Password:
bash-4.1# rm -rf /var/lib/rpm
bash-4.1# rpm --rebuilddb
bash-4.1# rpm --nodeps -i /var/cache/yum/updates/packages/centos-release-6-5.el6.centos.11.2.x86_64.rpm
warning: /var/cache/yum/updates/packages/centos-release-6-5.el6.centos.11.2.x86_64.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
warning: /etc/yum.repos.d/CentOS-Base.repo saved as /etc/yum.repos.d/CentOS-Base.repo.rpmorig
bash-4.1# yum install yum
<skip details>

Note

build-chroot is a command from my other HOWTO about making a Debian based chroot in Gentoo.

Now chroot is ready to use ;-)

TODO

Note

See Also