[OE-core] Using users/groups from another recipe than the one creating them

[Peter Kjellerstedt]

> -----Original Message-----
> From: openembedded-core-bounces at lists.openembedded.org
> [mailto:openembedded-core-bounces at lists.openembedded.org] On Behalf Of
> Mark Hatle
> Sent: den 9 juni 2014 16:47
> To: Peter Kjellerstedt; OE Core (openembedded-
> core at lists.openembedded.org)
> Subject: Re: [OE-core] Using users/groups from another recipe than the
> one creating them
> 
> On 6/9/14, 8:39 AM, Peter Kjellerstedt wrote:
> >> -----Original Message-----
> >> From: openembedded-core-bounces at lists.openembedded.org
> >> [mailto:openembedded-core-bounces at lists.openembedded.org] On Behalf
> >> Of Peter Kjellerstedt
> >> Sent: den 23 maj 2014 12:38
> >> To: OE Core (openembedded-core at lists.openembedded.org)
> >> Subject: Re: [OE-core] Using users/groups from another recipe than
> >> the one creating them
> >>
> >>> -----Original Message-----
> >>> From: openembedded-core-bounces at lists.openembedded.org
> >>> [mailto:openembedded-core-bounces at lists.openembedded.org] On Behalf
> >>> Of Peter Kjellerstedt
> >>> Sent: den 19 maj 2014 10:15
> >>> To: OE Core (openembedded-core at lists.openembedded.org)
> >>> Subject: [OE-core] Using users/groups from another recipe than the
> >>> one creating them
> >>>
> >>> Which assumption is correct: "a recipe A that depends on another
> >>> recipe B can use users/groups that B creates" or "all recipes must
> >>> create the users/groups they require themselves"?
> >>>
> >>> The problem for us is that we have a lot of recipes that create
> >>> users and groups, and subsequently a number of other related
> >>> recipes that need to use those users and groups.
> >>>
> >>> If the first assumption is correct then the useradd.bbclass needs
> >>> to be corrected so that it adds a dependency from do_install to
> >>> base-passwd:do_populate_sysroot and
> >>> base-passwd:do_populate_sysroot_setscene, because if either of
> >>> those tasks execute they will overwrite /etc/passwd and /etc/group,
> >>> effectively removing any users/groups that were created earlier...
> >>>
> >>> On the other hand, if it is the second assumption that is correct,
> >>> then there should be QA tests in place to make sure all recipes
> >>> create the users/groups they use.
> >>>
> >>> //Peter
> >>
> >> *ping*
> >>
> >> Doesn't anyone know how users and groups are supposed to work?
> >>
> >> //Peter
> >
> > *ping again*
> 
> I never saw the original emails, either of them.
> 
> > Well, this is somewhat discouraging. Three weeks and not a single
> > response. Are we really the only ones that care about users and
> > groups and how they are created? Doesn't anyone know which of my
> > two assumptions above are correct?
> >
> > Personally I would prefer that all recipes create the users and
> > groups they require themselves as this keeps them more self
> > contained. I have no idea how to write a QA test to verify this,
> > but I assume it should be possible...
> 
> The rule is:
> 
> There is a limited number of base users and groups, if your package
> uses a user/group in that base set nothing else is needed.
> 
> If your package needs an additional user/group, then it must either:
> 
> *) Add the user/group itself.  Multiple packages are allowed to add 
>    the same users/groups, with the understanding that the options 
>    -must- be identical!

I have actually been toying with an extension to the 
useradd.bbclass that allows one to configure the user and group 
options in one configuration file, and then just state in the 
recipes which users are needed. That way there is no risk of using 
different options for the same user if it is created from different 
recipes. Haven't finished it though. One thing I have not solved is 
how to handle requiring the configuration file from all layers as 
they may all need to add users (or what to do if multiple layers 
define the same user differently...)

> *) Must -require- (not recommend) a package that adds the group that
>    they require.  It's a good idea in the recipe to comment that the 
>    'require' adds the user/group as well.
> 
> This is pretty common where a single recipe provides multiple packages.
> If a common package creates the user/group, then all of the other 
> packages [that need that user/group] should then require the common 
> package.

Ok, then my first assumption was the correct one. In that case I 
will look into fixing the useradd.bbclass so that the missing 
dependency is added.

> As far as the QA resources go.  There are actually two sides to 
> the QA. The first is in the do_install step, if the users/groups 
> are being used there -- and don't exist -- a failure should be 
> generated.  That exists just by the nature of the system build 
> processes.
> 
> The second is that once a package has been generated (the package
> directory that is), it should be verified that all files are owned 
> by in the base set of users/groups, the user/group has been added, 
> or a dependency on the package that added them exist.  This is 
> difficult to do though.  There is currently no tracking mechanism 
> in the system to say which recipes added which users/groups to the 
> system.  A mechanism similar to the sysroot file population would 
> be required to capture the user and group changes and by which 
> package(s). This of course would also have to work with the 
> sstate-cache mechanism.
> 
> The first step in implementing this would be to capture the 
> user/group changes and record them in a database.  (again, I think 
> similar to the populate sysroot file).  Then during the QA process, 
> you can iterate over the files and find out where each user/group 
> in use comes from.  If the provider is not in the 'required' set of 
> packages generate a QA -warning- (since this is new and unproven 
> code).. We can upgrade it to an error once it's stable.

Hmm, ok. This all sound like something we want. However, my Python 
skills are probably not up to the task, unfortunately.

> --Mark
> 
> > //Peter

//Peter