In maximum rpm under the section on the %pre install script, it mentions that it's rare to use the %pre script. In fact, it further states that (at that time anyway) none of the 400+ RedHat packages used the %pre script.
I would think the %pre script would be the ideal location to stop the existing service before installing files over top of the currently installed version.
Is my thinking wrong? How is it that RedHat got away with never using %pre during upgrade for this purpose in any of their service packages?
Yes %pre is much more commonly used than when "Maximum RPM" was written in 1997. That doesn't change the fact that %pre should be used "rarely".
The reason is that %pre prevents installation (and may cause an entire
transaction to fail if there are needed install time dependencies).
Stopping a service in %pre and restarting in %post opens a larger window
where the service is not running than simply restarting a service in %post
The already running service typically reads its configuration files
only on startup (and so rpm can replace files while daemon is running).
And running executables have a reference count on the file system and so
continue to run even if the file that was executed was removed/replaced
by a newer package.
Well, I went and did the research I should have done before asking this question. I downloaded several service packages from RedHat 7.1 and ran:
rpm -qp --scripts <package-name>.rpm
I found out 1) that it's no longer true that %pre is not used. Even among the few that I checked a couple of them used %pre, and 2) it appears that most services just allow rpm to overwrite their data files and binaries during upgrade, and then use the upgrade portion of the %postun (post uninstall) script to restart (or try-restart) the service.
I would have thought this rather unsafe, as while you're writing over data files (especially) during upgrade, the old running service might get confused. It seems to me ultimately it's safer to stop the service during upgrade on %pre and start it again on upgrade during %postun... but that's just me.
Related
I have some problems trying to test "needs-restarting -r ; echo $?" inside a RedHat distribution. The command works for cases where a reboot is not required, but I have not been able to voluntarily generate the need to reboot in the operating system, which has made it impossible for me to know if the response to the command works. That is to say the output in 1 of the needs-restarting. Do you know of any way to generate the need to reboot in a controlled manner in RedHat?
You can find which packages require a system reboot after the update to Redhat KB. If you can downgrade one of these packages, you can generate reboot required state. But this is not recommended in production systems. glibc and kernel downgrades can cause problems. You can try it at new installed Rhel server after "yum update".
I need to install Concourse(CI/CD) on my Local windows machine
Below process I followed :
Install Bosh on local system.
It was successfully install and while executing command at command prompt
then it show version all "bosh" -- "version 3.0.1-712bfd7-2018-03-13T23:26:43Z".
Try Download the concourse-lite deployment manifest file but it fails it shows below error.
Follow the below link to install Concourse :
https://concoursetutorial.com/ --- section For Windows:
I don't reccomend doing this at all because you'll be swimming so far out of the main stream that you'll find tons of issues and no one is going to care enough to want to fix them.
Even if you didn't find any issues, resources require a linux worker for anything to work so your going to need linux anyways.
I recommend running your db, web and linux worker on linux and then running windows workers as needed.
I have built a RPM-package for Centos 6.6 that is installed on a machine of our customer.
This package contains our own software, customized for the specific use case, but also uses the open-source package HAProxy.
HAProxy (RPM-version 1.5.4-2.el6_7.1) comes with a default-configuration in /etc/haproxy/haproxy.conf and it cannot be customized without changing this file.
But I want the configuration to be part my generated package. RPM throws an error if the /etc/haproxy/haproxy.conf file is in my package, because it is also part of the haproxy-package.
I have worked around this problem by providing a custom upstart-script which starts HAProxy with a different config file, but this does not seem to be the right way to do this.
Is there a preferred way to handle such customizations?
In cases like this, I've created an RPM which installs configuration files into a different subdirectory, and in its %post and %preun scriptlets modifies the uncooperative package's config-files:
when installing, I renamed the original config-files, and made symbolic links from those pathnames to the overwriting config-files, and
when uninstalling, the package removed the symbolic links and restored the original package's files.
Doing it that way of course meant that my config-RPM was dependent on the original RPM. A little awkward to describe, but it works.
In followup, the issue of updating was mentioned. Updating an RPM requires special handling to avoid uninstalling things. The rpm program passes a parameter $1 which you can test in the %pre and %preun scriptlets to notice that this is an upgrade and that there is no need to save the original config-files (or restore them). The rest of the scriptlet would be the same, by copying the new versions of your config-files over the others.
Further reading:
Defining installation scripts (shows the use of `$1)
RPM upgrade uninstalls the RPM
Your approach is correct. On EL6 and sysv there is no other choice than creating custom haproxy package or custom haproxy service or create script which customer runs after installation. I see creating another service as best option.
Note that on EL7 with SystemD you have much better option as you can use Drop-In feature of SystemD. For more information see:
https://coreos.com/os/docs/latest/using-systemd-drop-in-units.html
https://wiki.archlinux.org/index.php/systemd#Drop-in_snippets
https://wiki.archlinux.org/index.php/Systemd/User#Service_example
The usual way this is done is to have a drop-in configuration directory, e.g. /etc/httpd/conf.d/, where your package would drop its configuration, and you would tell the other daemon, e.g. httpd, to do a graceful restart in your %post/%postun.
I don't know anything about HAProxy, but a quick search implies that they do not support this configuration directory concept that has been around for many years. A few people have hacked it in, but unless it is out-of-the-box, you will run into your original problem again.
I installed virtualenv + virtualenvwrapper via virtualenv-burrito. However, it seems to be giving me problems now in uninstalling packages from my virtualenvs (case in point, distribute).
It seems that the distribute used by my virtualenvs is the one at /home/skrd/.venvburrito. If, inside a virtualenv, I try to upgrade distribute, it installs to /home/skrd/.virtualenvs but the virtualenv itself is still using the one at /home/skrd/.venvburrito. With that, the packages needing an updated distribute still won't work.
See,
(test)$ $ pip uninstall distribute
Not uninstalling distribute at /home/skrd/.venvburrito/lib/python/distribute-0.6.27-py2.7.egg, outside environment /home/skrd/.virtualenvs/test
I've tried renaming the .venvburrito directory (equivalent to deleting it, but with back-up) but that breaks my virtualenvs. How do I uninstall packages now?
I still don't understand what happened here but I just had the idea to check what's installed for my system's Python outside virtualenv. There I saw distribute, with a similar version to the one that's giving me problems inside a virtualenv.
I upgraded the non-virtualenv installation of distribute and, next time I checked in my virtualenv, the distribute installation has also upgraded.
(So, yes, I'm aware that my question's original intent is to remove distribute. But that was just an intermediary step to updating it---the update was unable to proceed since it can't remove the distribute currently installed. So, there, problem solved.)
I am revising one of our in-house RPMs that adds to the nagios package.
Originally our package would alter some files that were installed by nagios.
My new package undoes this methodology and takes an additive approach.
Is it possible to do something like this in the %pre section?
%pre
rpm --erase nagios
rpm --install nagios
When I run this it hangs here:
warning: waiting for transaction lock on /var/lib/rpm/__db.000
John
No way that I am aware of. If you need to do something special when nagios is modified, you can use %triggerin and %triggerout. I believe %triggerin will be executed when you install your RPM if nagios is already installed, but I don't remember offhand where in the sequence it will happen.