Attachment 848360 Details for Bug 1051649 – boot_testing.rpt

boot_testing.rpt

boot_testing.rpt (text/plain), 5.01 KB, created by Jonathan Lebon on 2014-01-10 19:04:05 UTC

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Creator: Jonathan Lebon

Created: 2014-01-10 19:04:05 UTC

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>____________
>INTRODUCTION
>
>This document explains the new boot-time probing feature and testing
>ideas. With this feature, users are now able to run their SystemTap
>scripts during the boot process. The feature was added to the
>initscript.
>
>To use it, users first place their scripts in /etc/systemtap/script.d
>and then run:
>
># service systemtap onboot my_script
>
>which will compile the script and recreate an initramfs image containing
>the resulting module. See [1] for a more complete introduction on how to
>use the feature.
>
>[1] https://sourceware.org/ml/systemtap/2014-q1/msg00012.html
>____________
>INSTALLATION
>
>The easiest way to use the feature is to create RPMs and install the
>systemtap-initscript package. It will install both the systemtap
>initscript (as before), as well as the dracut module needed to bake
>SystemTap modules into the initramfs.
>
>If manual installation is required, first build systemtap, then copy the
>following files:
>- initscript/99stap/* to /lib/dracut/modules.d/99stap
>- initscript/systemtap to /etc/init.d/
>
>Replace/remove the Automake variables (e.g. ${prefix}) as well.
>_____________
>DOCUMENTATION
>
>The main documentation for this new feature resides in README.systemtap,
>which is installed in </usr/share/doc/systemtap-initscript-2.5/>.
>Especially relevant are sections 2.2.6, 2.3.6, 2.3.7, 3.7, 4.1.12, 5.9.
>If you are already familiar with the initscript, it may be easier to
>instead look at the documentation diff:
>
>https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=commitdiff;h=b0d4bb7
>______________
>THINGS TO TEST
>
>For many of the tests below, you don't necessarily have to reboot the
>system for testing. You can just inspect the files created or the output
>from the initscript.
>
>1. Initscript testing
>
>- Make a basic script, put it in script.d, use onboot, reboot the
>  system, and attach to the module to verify it inserted properly.
>- Same as above but with more than one script.
>- Try using onboot for another kernel version using -r.
>- Try using onboot to output another image file using -o. At boot-time,
>  you can specify the other image file by editing the command-line
>  parameter at the grub menu.
>- Both of the above together.
>- Try using onboot with the -b switch. The old initramfs should be
>  renamed with a .bak extension.
>- Try using onboot with the -b switch and the .bak version already
>  existing. The existing backup shouldn't be overwritten.
>- Try using onboot without any scripts mentioned and verify that no
>  SystemTap-related files make it into the new image (you can use
>  'lsinitrd | grep' as mentioned in the next section
>
>2. Dracut testing
>
>- Turn on the LOG_BOOT_ERR setting and verify that the logs are created
>  at boot-time in /var/run/systemtap/ (or whatever STAT_PATH is)
>- Use a different STAT_PATH and verify that the 'status' command still
>  works as expected after using a boot-time script.
>- Verify that options put in /etc/systemtap/conf.d have an effect:
>   - Make a script that required guru-mode and check that onboot only
>     works when e.g. myscript_OPT="-g" is in conf.d/myscript.conf
>   - Add the -o option to myscript_OPT and verify that onboot doesn't
>     accept the script.
>
>3. Package and compatibility testing
>
>- Install on F19+ or RHEL7+ and verify that the dracut module was
>  installed at /lib/dracut/modules.d/99stap.
>- Install on lower platforms (e.g. RHEL6) and verify that the dracut
>  module did not install.
>- Install on RHEL6 and verify that it refuses to run onboot due to not
>  finding the dracut module.
>- Install on RHEL5 and verify that it refuses to run onboot due to not
>  finding the dracut program.
>_______________________________
>USEFUL TESTING TOOLS AND TRICKS
>
>- After you've created a new initramfs and booted up your system, you
>  can use
>
>  # service systemtap status
>
>  to first check that the script is even running.
>
>- In general, it is better to disable the systemtap service during
>  testing, because otherwise, you may not know whether the script
>  started running since boot, or since the init script started it. To
>  disable the service, simply run
>
>  # chkconfig systemtap off
>
>- If you ever find yourself in a situation where you can no longer boot
>  into your kernel, then boot into a previous version and run
>
>  # service systemtap onboot -r <KERNEL_VERSION_THAT_DOESN'T_BOOT>
>    OR
>  # dracut --force --omit stap --kver <KERNEL_VERSION_THAT_DOESN'T_BOOT>
>
>- Use the lsinitrd utility to inspect initramfs images. This is useful
>  when you just want to check if a file made it into the image without
>  having to test it by rebooting. For example:
>
>  # lsinitrd
>    OR
>  # lsinitrd /boot/my_custom_image.img
>    OR
>  # lsinitrd -k <KERNEL_VERSION_OF_IMAGE_TO_INSPECT>
>
>  Another example, checking if staprun is in the image:
>
>  # lsinitrd | grep staprun
>
>- To debug dracut, add 'rdinitdebug' to the kernel command line. Dracut
>  will echo all the commands it executes in journalctl -ae.
>
>- If the initscript fails to compile your script, the errors will show
>  up in /var/log/systemtap.log.
>
>- If dracut fails to create the initramfs image, the error will show up
>  in /var/log/dracut.log.

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