How to make a package dependant on a class for the repository.

[Stack Kororā]

Greetings!

tl;dr Why doesn't require=>Class work?

I have a module I built that I creatively called "repos". This does a number of things for me:
* I have many systems on different networks. Depending on the network depends on which repository the servers get their packages from.
* I have many OS's (RHEL, Scientific, CentOS, SuSE) and several different releases of those OS's (ex: RHEL6 vs RHEL5).
* Some systems get repositories that others don't (ex: VMware guests get the ESXi guest tools repo).
* We roll our own packages for some software; only systems of a certain type get these repos.
* ect.

This class does a wonderful job for me. I barely have to do anything in the node definition other than "class { 'repos': } " and it just figures out which systems get what repo's based on facter and various parameters (like current network IP).

Here is the problem though.
package {["htop":ensure=>installed, }

Chances are *really* good that on first runs when the repo hasn't yet been created, what will happen is:
* Error: can't find htop.
* Installing EPEL
*Done!

Well that isn't what I want, obviously. Thus I tried:
package {["htop":ensure=>installed,require=>Class['repos'],}

Still the same result as before. It never fully configures the repo before trying to install. Then I tried:
package {["htop":ensure=>installed,require=>Yumrepo['EPEL'],}

It works!! Hooray! And then I hit a failure point. This next statement works for Scientific Linux but fails for CentOS6 because a CentOS system won't have the SL6 repo!
package {["tuned":ensure=>installed,require=>Yumrepo['SL6'],}

I have come up with two "solutions".
1) Change all the repos to use generic names like "Base" and "Security". While it is a big bandaid, it doesn't really fix the problem as there is still potential for packages to conflict.

2) Find out why "require=>Class['repos']" doesn't work and fix it. This would solve all my problems if the repos were run and configured properly before packages were installed. The only "problem" would then be to make sure I am not trying to install a package that legitimately doesn't exist in the repos (like tuned on a CentOS 5 box) but that would fall squarely into a PEBKAC and there is only so much I can script to catch those. :-)

Can anyone help me with this please? Any ideas on how I can fix this?

Thanks!

[joe]

Does your repos class have a bunch of classes included? If so, those are not caught by the require and you need to use the anchor pattern:

http://projects.puppetlabs.com/projects/puppet/wiki/Anchor_Pattern

The ordering (no matter how you do it) only orders the *resources* in that class. Not the resources in classes that are *included* in your repos class.

[Stack Kororā]

Thank you very much Joe. I think this exactly the path that I need but I am having trouble with it.

As I said, I have multiple systems that this repo class watches over. Thus, for one of several instances, I have things like:

if $osfamily == 'RedHat' {
    class {'repos::epel': }
}

The sub-class epel.pp file configures the EPEL repository for the RHEL, Scientific, CentOS, Fedora, ect. However, trying to anchor that caused a bunch of odd errors (it is entirely possible I didn't do it right).

I also have the main configuration in a large case statement that manages the main configuration in sub-classes for all operating systems (thus only some sub-classes are ever called). This too is causing me some issues.

I think it is because I don't fully understand how the anchor is supposed to work and the examples listed are a bit simplistic with both a require and a notify. But what if I need it to require only if it matches certain parameters?

I poked around in a few other modules seeing if I could find more examples, but came up empty.

Does anyone know where I can view more examples/code for some guidance?

Thanks!

[Wolf Noble]

Hi Stack,

here's an example:

https://github.com/wolfspyre/puppet-mysqlx/blob/master/manifests/v55.pp

in this class I create a pair of bookend anchors, and then shove a yumrepo, and a file resource between them.

Your other classes/resources can then declare a relationship to the end anchor to establish the relationship.

some gotchas:

- Make sure to include the class declaring the anchor into the class which has the dependency. 

- Remember that you've just permanently established a relationship between these two classes. This is important to know, and can take you in a direction that leads to complications down the road. 

- It is common to have specific software classes depend on your base-type 'i set up my package repositories, and some other core things that will happen most everywhere' resources. The caveat here is that modules you share with the world will NOT have that base class, and as such may have dependency issues.

- Use the anchor pattern as sparingly as possible. Consider having to use it like having to resort to an exec. It is occasionally the right tool for the job, but not usually.

Hope that helps.

Thanks!

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[Stack Kororā]

Thanks for the quick reply! And the example!  Let me review this and try it out. I will post back if I run into any issues.

Thanks again!

[Stack Kororā]

Just wanted to say "Thanks!" again. The example helped out quite a bit and I was able to get it functioning the way I wanted it to (at least so far! :).

Thanks!

[linde...@gmail.com]

A way to work around your problem may be to use stages:

class { repos: stage => first } #you may define stages before

So all repositories will be available before the first packet will be installed.