[Yum] dependency problems with yum-priorities on CentOS 5.5

[Ljubomir Ljubojevic]

Nick wrote:
> On 23/08/10 13:05, Ljubomir Ljubojevic wrote:
>> All you experienced is exactly how it is supposed to be.
>>
>> Yum-priorities does the following:
>> ALLWAYS use version of package from repo with lesser priority number.
>> For all OTHER packages, use version of package with lesser priority number.
>>
>> I use it like this:
>> Priority plugin is active always. If I hit dependency problem like you
>> did, there are two things you can do:
>> a) do not install package with unresolved dependency
>>
>> b) run install with "--disableplugin=*prior*" and IGNORE that external
>> repo will mess with your system, replacing packages yum-priorities is
>> installed to protect.
>>
>> For smaller insignificant packages I would select
>> b), but very carefully.
> 
> Thanks.
> 
> My main point is that I don't have any way of knowing there *is* a dependency
> problem until it is too late and "yum update" has installed half of the updates
> and aborted on the bad one.

Yum runs Transaction TESTING, and THERE it reports problems with deps or 
files, not in actual transaction.

> If yum told me before it started, I could then opt for a) or b) as you say, and
> I'd not be so uneasy about yum-priorities.  I don't understand why it couldn't,
> as it seems to have access to all the dependency information it needs to find
> out. In fact, I can see no way of finding out in advance, besides running the
> update on an identical, sacrificial server.
> 
> N

It is very simple. First you run updates with priorities enabled, and 
update all core repo packages and already installed external packages 
without their counterpart in core repos, that (highly likely) have no 
unresolved dependacies.

After that you will be left with none or handfull of external repo 
packages. You either update them one by one with priorities disabled, or 
all at ones (with priorities disabled) and see if you have problems.

I refuse do install packages on my server that change core files. 
Nothing is worth the hasle or instability.