The Yum-based SPMA alleviates greatly the RPM dependency hell. This is done by shifting the burden on maintaining each package to maintaining properly our repositories.
If you used to just download many repositories into the same directory, or put RPMs from many different sources in the same repository, you will find yourself in a lot of troubles with the new SPMA.
These are some recommendations to avoid such a situation.
Repository layout
Each upstream repository you choose to follow must become a separate repository in your site. Combining repositories is a very bad idea.
You will also need a set of repositories for your home-grown software.
At UGent we do it like this, for SL6:
- Base
- Updates
- Fastbugs
- EPEL
- RPMForge
- atrpms
- jpackage
- quattor
- Private from vendor 1
- Private from vendor 2
- Home-grown
- Quattor
That’s a fair number of repositories. And we are considering whether to split the home-grown repository.
Less important repositories
Some of these repositories will be listed only for debugging purposes. This way, we may allow an administrator to run
yum --enablerepo=* install <some-debugging-tool>
that will be cleaned up after he’s done his operations.
Those will be disabled in the repository template, like this:
structure template repository/foo;
...
"url" = "http://...";
"enabled" = false;
...
Blocking a repository except for a few RPMs: the case of RPMforge
A more frequent use case is RPMforge. It has many useful packages
that your distribution does not provide. But it will also collide
with the distribution for many other packages, and we usually want to
follow the distribution.
In those cases, we want to install only an explicit set of packages
from RPMforge. And not even consider it for the rest of our system.
That’s where Yum’s includepkgs comes in handy. You just give the
list of packages you need from that repository, and for the rest of it
it will be effectively disabled. In your repository template:
structure template repository/rpmforge-el6-x86_64;
"name" = "rpmforge-el6-x86_64";
"owner" = "foo@bar";
"protocols" = list(
nlist("name","http",
"url","http://repos.foo.bar/mrepo/RPMforge6-x86_64/RPMS.all")
);
"includepkgs" = list("foo");
Wildcards are allowed in the includepkgs list.
Blacklisting packages from a repository
You can use Yum’s exclude directive for blacklisting packages from a
repository. In your repository template, that would be the
excludepkgs directive.
Repository priorities
I don’t really recommend using priorities. They will interact in many surprising ways when you want to use specific versions for some packages. Selectively enabling or blacklisting some packages usually works better.
In any case, should you really want them, just set a priority for
your repository template.