[CentOS-virt] Re: LXC on CentOS 7 HowTo: PAM Configuration

Tue Feb 9 18:47:31 UTC 2016
Yamaban <foerster at lisas.de>

On Tue, 9 Feb 2016 10:32, Jochen Wiedmann wrote:
> Hi,
> I am trying to implement something like an "LXC on CentOS 7 HowTo" for
> internal use. (Might as well get public afterwards.) I am following
> the HowTo for CentOS 6
> (https://wiki.centos.org/HowTos/LXC-on-CentOS6). So, here's what I did
> so far (Steps 1-6 can easily be omitted, but I am trying to be
> complete.)
> 1.) Disable delta RPM's in /etc/yum.conf
Well, that needs a explicite explanation on the WHY, IMHO not needed

> 2.) Remove LibreOffice
>    sudo yum remove "libreoffice*"
Well, that is personal taste, the existence of a installed LibreOffice
should not influence LXC in any way.

> 3.) System update
>    sudo yum -y update

This should be first point. No one should start a installation of
such a complex matter as Virtualisation on a outdated system.
Best add comment about the use of "yum ps" or the real need
of a reboot in case of glibc/udev/kernel updates before going
further in installing.

> 4.) Install some niceties
>    sudo yum -y install emacs emacs-nox "@Development Tools" git subversion
Again personal taste, for some is the installation of emacs a sacred act,
for other pure blasphemy. say something about making sure the the
favourite text-cli editor is installed is more helpful here.
Remember the UNIX way: Less is more. Less software on the host(metal),
means more uptime between unavoidable reboots, esp. for servers.

> 5.) Reboot
> 6.) Install VirtualBox Guest Additions
Eh? You want to use LXC, not "VirtualBox", what are the "Guest Additions"
for? Explain, if really needed

> 7.) Install libvirt
Give better title here, e.g. "Install packages for LXC: libvirt + co."
>    sudo yum -y install libvirt libvirt-client libvirt-install
> 8.) Setting up root fs for a container:
>    sudo su -
>        mkdir -p /var/lib/libvirt/lxc/centos01/etc/yum.repos.d
>        cat cat /etc/yum.repos.d/CentOS-Base.repo | sed
> s/'$releasever'/7/g
> > /var/lib/libvirt/lxc/centos01/etc/yum.repos.d/CentOS-Base.repo
Ok, that can be done better, and easier to read and understand:
   cp -t /var/lib/libvirt/lxc/centos01/etc/yum.repos.d/ \
   sed --in-place 's/$releasever/7/g' \
If you really need the switched of "Delta RPM" stuff, here and now is the 

>        yum groupinstall core --installroot=/var/lib/libvirt/lxc/centos01
>        # The following command seems to be redundant, as both
> packages are already installed as part of the core group.
>        yum -y install plymouth libselinux-python
> --installroot=/var/lib/libvirt/lxc/centos01
> Now, according to the old howto, I am to configure PAM in the new root
> fs. Reading through that; I don't really understand what I am to do.
> For example, I am to replace a line with "session required
> pam_selinux.so close". However, the matching line is a comment line,
> which makes me unsure.
> Are those PAM configurations still required? If so, could someone help
> me on what to do exactly?
> Thanks,
> Jochen

I have not needed any pam-monging so far, but ... [shrugs].

Please, some other (real-live) expert, go over the installation procedere, 
too, I'm no guru, nor a last instance.

Lets give enough input to make this HowTo conform to best practises.

  - Yamaban.