Kickstart: How log and view %post? Method works in CentOS 5 but not CentOS 7

[Ross Smith]

I missed your first email, but we do this in our installs.


The el7 anaconda uses tmux underneath, which can be exploited to display
whatever you want or even interact with a user.

The first thing we do, is change the provided rsyslog.conf to log to our
central server, which serves most of our needs.  something like the
following in a %pre script will get you most of the logs from the installer:

# wget https://your.server/rsyslog.conf -O /etc/rsyslog.conf
# systemctl restart rsyslog

This can be further used to display logs using some tmux commands. e.g:

# tmux new-window -a -n logging 'tail -F /path/to/log/file.log'

We take this a step further, and use tmux to run our %pre and %post scripts
directly.

# tmux new-window -a -n prescript 'python /tmp/pre.py'

# while [ ! -f /tmp/predone ]
# do
#	sleep 1
# done

# tmux kill-window -t prescript

This sort of setup can also be used with xloadimage to launch a
non-blocking script to paste an image to the screen while the text mode
installer is running.

I hope this helps.

Ross Smith <rjsm at umich.edu>
College of Engineering - CAEN - Linux Support

On Wed, Mar 2, 2016 at 4:45 AM, therbur <fxb7-ox9n at dea.spamcon.org> wrote:

> Since nobody responded, I spent days looking around on this and
> experimenting.
>
> It makes no sense to me that the ability to both log and display
> output is not intrinsic to kickstart.
>
> Note that the %pre --log parameter does not work, it always
> results in a 0-length log file.
>
> Also, the example of that option in:
>
>
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Installation_Guide/sect-kickstart-syntax.html#sect-kickstart-preinstall
>
> is completely wrong anyway because it's logging %pre output to
> the non-existent built image.
>
>
> Summary of the solution that works for me for CentOS 7 kickstart:
>
>
> %pre --erroronfail
>
> exec < /dev/tty3 > /dev/tty3
> chvt 3
>
> (
>
> echo ...
>
> ) 2>&1 | /usr/bin/tee /tmp/pre.log
>
> %end
>
>
>
> %post --nochroot --erroronfail
>
> cp /tmp/pre.log /mnt/sysimage/root/
>
> %end
>
>
>
> %post --erroronfail
>
> exec < /dev/tty3 > /dev/tty3
> chvt 3
>
> (
>
> echo ...
>
> ) 2>&1 | /usr/bin/tee /root/ks-post.log
>
>
>
> therbur <fxb7-ox9n at dea.spamcon.org> wrote:
>
> >The following method has worked for years with CentOS 5, to allow
> >live viewing of %post output and also logging it.  It doesn't
> >work in CentOS 7.  What is the recommended method now?
> >
> ># from kickstart text mode install
> >
> >%post --erroronfail
> >
> >chvt 3
> >exec < /dev/tty3 > /dev/tty3 2> /dev/tty3
> >
> >tail -F /root/ks-post.log &
> >(
> >
> >echo "Starting post-kickstart ..."
> >
> ># ... various commands
> >
> >echo "Done."
> >echo
> >echo "Do Alt-F1 and press Enter to reboot"
> >
> >) >> /root/ks-post.log 2>&1
> >
> >%end
>
>
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>
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