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yjl-sysusers

VERSION 0.1.5 PRE-RELEASE

For installation instructions, see INSTALL.md

This project includes a single utility and a JSON file. In the git source, that utility is simply called functions.py but it gets installed as /usr/sbin/yjl-sysusers with a single-line change to specify the location on the filesystem of the JSON file.

This project is currently being developed using Python 3.11.3 but it has been tested in Python 3.6.4 (CentOS 7.9.2009) without issues.

The purpose is to provide an easy way to provide consistent static user ID and group ID numbers for system users (as opposed to human login users) while also being able to on-the-fly use dynamic IDs if the static IDs have already been used for something else.

My use case is for RPM %pre scriptlets to ensure that the appropriate users and groups an RPM package needs exist when the package installs.

yjl-sysusers

With the yjl-sysusers utility, portable RPM spec files which produce packages that are installable across multiple LSB compliant GNU/Linux distributions (sometimes with a rebuild for shared library resolution) becomes much easier.

Theoretically (not yet implemented or tested) with the yjl-sysusers utility, translations of user comment (also called GECOS) /etc/passwd field into the default system locale will be automatic, assuming the translation is available.

See the yjl-sysusers.8 man page for usage.

yjl-sysusers.json

The yjl-sysusers.json file in the top-level directory of the source tarball is tailored to YellowJacket GNU/Linux.

The yjl-sysusers.json file installed by a package manager should be tailored to the distribution the package is built for.

This JSON file includes the distribution-specific static UID/GID assignments for certain users and groups, as well as distribution- specific configurations for how to handle things like dynamic UID/GID allocation.

A network or organization administrator of multiple systems—even different distributions—can customize the JSON and rebuild the package to add specific static allocations that are needed for use cases specific to that network or organization.

For the file format, see yjl-sysusers.json.5 man page.

As long as yjl-sysusers.json matches the specification of your distribution and the requirements of your distribution, you should be able to install this package and then any RPM package that uses yjl-sysusers to ensure system groups and users exist should do the right thing on your system.

Validation Failures and Handling

If the JSON file is malformed, the yjl-sysgroups utility will exit with a failure status. That should never happen unless the JSON file is improperly modified after install.

If the user running the yjl-sysgroups utility does not have root privileges, the utility will exit with a failure status.

If a username or groupname passed as an argument does not validate, the yjl-sysusers utility will exit with a failure status.

If there are no available UIDs/GIDs left in the system user dynamic range when one is needed, the yjl-sysusers utility will exit with a failure status.

Other than those cases, failure of the program should be extremely rare and considered a bug.

As the intended use is within RPM, it is better for the program to choose a safe default and continue (such as using /dev/null for the home directory or /sbin/nologin as the login shell) if a bad value is passed to yjl-sysusers so that the user is created and the proper assignment of files belonging to users and groups the script is asked to create can still be made.

Python Notes

Python 3 is required. A few distributions (like CentOS 7) are still at present supported that use Python 2 as the distribution Python interpreter, but AFAIK all of those distributions offer Python 3 as well.

One feature I know requires Python 3.6+, the script has been tested in Python 3.6.8 (CentOS 7.9.2009) and it works.

I strive to always have a pylint score at or above 9 but even when at such a score, reported issues should be looked at.

False positives are disables and global keyword warnings are disabled, this utility has a genuine use case for the global keyword.

The pylint utility reports that the adjust_username_object() function has too many forks. That function has a lot of options to adjust for and I suspect refactoring that function to make pylint happy would only decrease readability.

The pylint utility also reports some No exception type(s) specified (bare-except) warnings.

At least some of those are safe to ignore, but I do not feel comfortable disabling that warning. It may be possible to properly deal with all of those cases.

My Arrogant Distribution Packaging Rant

By ‘My Arrogant’, I do mean me.

I literally HATE distribution specific macros and how they have proliferated in quantity and complexity since the ‘Good Old Days’.

Now get off my lawn, ya damn youngsters! Humor aside, it does seem RPM packaging is losing the KISS 😛 concept and I think that is bad for GNU/Linux.

A desktop user should not have to be a packaging guru in order to successfully rebuild a spec file written for Distribution A on the user’s Distribution B system. That is incredibly frustrating and encourages users to just not utilize the package management system, often leading to future problems and frustrations.

Something as simple and universal as ensuring the proper system users and groups exist should not, for example, require a systemd-rpm-macros package and the installation of a package-specific user metadata file that often only have meaning to a specific distribution.

What the frack does SystemD have to do with basic Un•x user and group management?

Yes, Fedora, I am talking smack about you. You are no longer the distribution I loved when Red Hat Linux became Fedora Core.

Most RPM based distributions are guilty of the same thing, clearly making RPM unsuitable as an LSB-mandated package manager.

I like RPM when used properly, but it is too easy for GNU/Linux distributions to do the wrong thing and decrease cross-distribution compatibility.

Some added complexity is sometimes necessary, but SystemD being required for fundamental user and group management? No. Just No.

Nancy Reagan: Just Say No (national archives PD)

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