Episode: 1016
Title: HPR1016: Nix: The Functional Package Manager
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr1016/hpr1016.mp3
Transcribed: 2025-10-17 17:27:24

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Hi, my name is Kylinder Oste, I use the nickname Govny with various parts of the Internet.
And I'd like to talk about the NYX project.
This is on NYXOS.org and it's actually a collection of open source projects including
NYX itself, the purely functional package manager.
I'll just read what it says on the page because it describes it better than I can.
So this means that it can ensure that an upgrade to one package cannot break others, that
you can always roll back to previous versions.
That multiple versions of a package can coexist on the same system and much more.
NYX packages is a collection of packages, NYX expressions which can be installed and NYXOS
is a NYX distribution which supports atomic upgrades, rollbacks, multi-user package management
and it has a declarative approach to system configuration management that makes it easy
to reproduce a configuration on another machine.
And also part of this suite is Hydra which is a continuous build system, it's a build
farm if you like, it creates the binary packages from these expressions.
And also there's Disneyx which is a deployment system so if you're familiar with things
like poppets or a CF engine or stuff like that, this can be used for that type of thing.
The NYX package manager can be used independently of NYXOS.
You can actually use it to install packages on top of Debian or Red Hat or even to a lesser
degree on Mac OS X and even to a lesser degree on Windows.
So I've been using the NYX package manager myself for a couple of years now.
I started using it on Debian stable as I mean it's to update Firefox and my window manager
and things like that without interfering with the base system so I could get all the security
patches from Debian and be sure that my base system was solid and then pick and choose
whatever updated packages can live or whatever that I cared about I could update that independently
using NYX package manager.
And after a year of doing that I decided to switch to NYXOS proper and I still do use Debian
in virtual machines for development.
So according to the NYXOS website itself it describes it as an experimental GNU Linux
distribution that aims to improve the state-of-the-art and system configuration management.
In existing distributions actions such as upgrades are dangerous.
Upgrading a package can cause other packages to break.
Upgrading an entire system is much less reliable than reinstalling from scratch.
You can't safely test what the results of a configuration change will be and you cannot
easily onto changes to the system.
So I've been running Linux myself for about ten years and I've tried loads of different
distros.
I started off on Mandrake and that really got me into things that worked really well and
I decided then that I was going to give up my job as a ASP web developer and really
getting to open source proper and I wanted to learn more so I thought I'd run Gen2
for a while and I did the LPI exam and things like that when I tried to Ubuntu and Mint
so I tried to arch for a short while and so you have this choice with Linux distros.
You can choose a stable release cycle distro like Debian, Red Hat, Ubuntu or you can choose
a rolling release.
You can have Gen2 or Arch but what I really wanted to do was to have an operating system
I could depend on.
I need this for work.
I need to use this every day.
I need to know that I can turn on my computer and I can do my work.
But I also need to have the latest browser for work as well and I also like to be able
to install software.
I don't want to think that if I install a video editor that maybe this will break strange
things and I'll have to spend hours trying to debug what it is before I can use my operating
system for doing anything else which can happen.
I mean on the CadenLive website it says that if you want to install CadenLive the video
editor on Debian the first step is to upgrade to DebianUnstable.
Now it's probably an oversimplification.
I mean it may well be possible to pin the Qt libraries and ffmb or whatever other dependencies
you need and create some configuration in Debian stable which allows you to actually compile
the CadenLive for your system without compromising.
But it's not simple and this is where the nix package manager fits in beautifully I think.
I'd like to quote Aben Moglem slightly out of context actually but he said in 2009 he
was actually talking about the freedom box but he said that the architecture of technology
in the past 20 years has largely been about the making of platforms rather than communities.
You know what platforms are, platforms are sticky things, it's difficult to fall off.
So for a commercial operating system it makes a lot of sense to have this stable platform
idea.
You can release a set of libraries and a complete operating system and the promise to third
party developers and users is that this will be the basis for the next few years.
You can build upon that and everybody who wants to support your platform just has to
care about that one configuration.
And as everybody knows this isn't the case in Linux there are loads of different distros.
So if you're a software developer and you want to make your software available to the
Linux community there's kind of this burden for ensuring that your software works with
every conceivable version of every library which is out in the wild.
The thing is it just doesn't make sense for everybody who writes free software to agree
on everything that okay everybody's going to use this library and we're not going to
change for the next five years because it's better for everyone.
This is the thing you'll see often debated about like one of the problems of Linux and
free software is that it's not a platform and that third party developers or say whoever
proprietary software developers don't have a target platform.
They can't just like release one thing and distribute it.
They have to like take into account that there's all these variations out there.
But actually to my mind the major stable releases are an approximation of a platform.
It seems like the idea of having long term releases or in fact any kind of release cycle
at all is to provide people with something some approximation of a platform and sometimes
also here it suggests that if everybody just ran Red Hat or Ubuntu or something then
Linux would be excellent.
It would be so much easier for developers and also for people who wanted to use Linux
because there's less of this overhead.
I know there's loads of alternative approaches to tackling this issue including Ubuntu
PPAs and Fedora also has their own package system.
What I really want to do is present the next package management system and just explain
roughly how it does what it does and I think it has some really interesting ideas.
I just see this whole thing as an important issue for Linux and I would love if we have
these features I wouldn't care if they were implemented in Debian or Fedora or whatever
I think it's really valuable to have these features for the sake of the flexibility you
get and the confidence you can have in your operating system if you can upgrade any package
that you want without fear of your whole system breaking and if things break you can roll
back to an older version just instantly.
I kind of actually feel that there's this culture and free software that things are supposed
to break and that because you benefit from all the hard work that these developers and
maintainers put into the distros that it's your responsibility to fill out bug reports
and to fix your own computer when things break that's like as a member of the free software
community this is what you should do.
Thing is it's not always the most convenient time to just put everything aside if your
computer is broken you can't do anything else you have to fix your computer right now
whereas having this ability to roll back to a working version quickly means you can get
download whatever you want to do you already have the broken system waiting for you to look
at it whenever you have time but it doesn't disrupt you from continuing to work on whatever
you want to and in general this means you can be more productive you can use your computer
when you want and then you can decide okay when it suits you you can be an active member
of the community and actually because of the way that the next system works which I will explain
a little bit you can actually debug quite accurately which perhaps conflicting libraries are involved
or what the underlying issue is and you can hand someone you can actually point someone to a
closure of the package which they will be able to see exactly what build inputs were involved
and what compile time options were involved and they can reproduce exactly the issue very quickly
okay so what is this next thing it's a functional package manager
okay so let me read from Wikipedia about functional programming in computer science functional
programming is a programming paradigm that treats computation as the evaluation of mathematical
functions and avoid state and mutable data so what is this got to do with software on your system
okay so if you open your terminal and type RS let's just think for a minute what happens
so it looks on your environment variable called path for the lists of directories where
it can find this command that you just called ls will probably find it in slash bin as a
mirror and then it runs us okay now the point is that in slash bin you have this binary ls
which lists the files in their directory but let's say that you upgrade your system and ls
changes and some bug has been introduced and it instead of listing files it removes all your
files or whatever so but when you call ls from the can line it's going to look up and it's going
to find that command and run it and what's happened is it's very much like a global variable
in a programming language you've got this one instance called ls which exists in slash bin
and if you replace it it's gone there's no way to like look up what was the last version of ls
that I had so I think this is what we mean by side effects in non-functional programming languages
this state has been changed of your environment the file system hierarchy standard for Linux is a
convention which describes where things should exist in the file system so for example slash bin
or slash e2c for configuration files and this is the point where nix is a bit controversial it does
try to stick to the file system hierarchy standard but it uses this trick
nix puts all the packages and configuration and stuff into slash nix slash store and in there
there's a directory for each package and the name of that directory is calculated so that
is unique to that derivation so if you change anything about the let's say the compile options
or the version of a library which is used to build a particular application or whatever
a new directory will be created and that application that binary or related configuration files and
everything will be put in there and then so the software is prepared it's usually available as a
binary which is being built by the hydra and build system the build farm and download it onto your
system and this path is created and then and this is when the notion of atomic upgrades comes in
because the place in your path environment variable that points to a sinlink which points to
somewhere in the nix store which describes your current environment your profile and that gets
updated to include a link to that version of the package now this is all a bit too complicated to
kind of cover in depth but the basic idea is that you don't have this single binary which gets
overwritten every time the software changes you have every version which you care about is available
in the next store and all you need to do like you can run any of them directly if you want they
have a complete set of dependencies so if for some reason you've upgraded any piece of software
and you realize something is wrong all you have to do is roll back to the last version
okay so you're probably thinking oh my god this is going to take up loads of hard drive space okay
whenever you decide that basically everything is working maybe upgraded last weekend you
haven't had any problems so then you can go ahead and do the garbage collection and remove those
old versions from your store typically they'll stay in hydra so if you ever want to download them
again you can just go on to the hydra website and click and install that exact version with all
dependencies and configuration options and everything as they were this also means that you can
have multiple versions installed at the same time without any conflict this is really cool if you
want to test some experimental software you can run anything you can have the most crazy experimental
cutting edge libraries which aren't even beta yet and you can install a package and run it
and you can keep your default version of the same package without any interference and you can
remove it and it's not going to your computer isn't going to blow up and you can just uninstall
that or keep it under a different name and use it for testing purposes and just report bugs or
whatever just in case there's any confusion the dependencies of an application where they're
shared between different applications they're also shared in Nix there's like a separate store
path for each library and it uses we'll say for some things it might use an environment variable
we'll say for Python it'll be Python paths so that a predictor application can find exactly the
version the Python modules it needs for a compiled stuff it might use our path so that they're linked
to to an application is linked dynamically to particular and library so actually it doesn't use
all that much more space it just uses more space for things which are different so obviously if
you have two separate libraries and you want to have two versions of an application compiled with
these two separate libraries that's going to take up more space but just to give you an example
I have like a full desktop system KDE those of audio applications and a few generations in
there which I could roll back to and that's like 10 gigs another nice feature is that she can
go in and override any of the Nix expressions Nix actually uses a domain specific language which
is specifically designed for managing packages installing packages and configuration options
so you can use this language to configure your system and this is also how you will add new
packages if you want or tweak some of the options for existing packages on your system so if you
want and quite typically people describe their system configuration in a configuration.nix file
and that can include what packages you want to have installed your default window manager if
you want to run SSH on a particular port anything essentially this is also what you can use
for the deployment options with Disneyx that's not something I've had to look at myself
but it sounds quite cool I mean if you want to have a configuration for a whole cluster of machines
you can do that and you can even do incredible stuff like you can you can have a configuration
for a cluster and then you can instantiate it on your test machine and get it to run various
VMs with those exact configurations you could for example set up a SQL server on one VM and then
you could have a website and another VM and you could have them configured so that the website
is accessing the SQL server from the other VM and you could test that that whole system works
on your own local machine and then you could decide okay this works you can actually
write tests which will look for things using the nix language as well but once you're happy
you can like you can do your automated testing and then you can also deploy that exact system
on bare metal okay so I've already mentioned that there's this hydra build firm which builds
the packages if you change a configuration option we'll say a compile option or you want to
test something out locally you will have to build that package locally there's essentially this
hash that I described earlier that will have changed and nix will find that it would look for that
on hydra and realize it doesn't exist yet and then it will decide to build it locally so that's
that's how it falls back to building packages from source and they're not available it also has a
feature where if you have a binary version of a particular application and there's been an
upgrade then hydra prepares binary deltas so you only actually have to download the piece of the
binary file which is changed you don't have to download the whole thing if it's like Libra
Office or something and something small has changed you only have to download that tiny bit
another feature provided by hydra is I think I mentioned it already the single click installs so
you can look at any package there and so there will be a link if you have the nix package manager
installed on any distro you can click on that link and that will download all these paths and put
into your system into your store and then activate them so that you can use that exact version
which is pretty handy and the other thing is that you can set it up so that any
unprivileged user on your system can also install packages and they can have their own versions so
if you have a multi-user system you could have two quite different systems essentially using the
same or using whatever versions of packages they want and they can manage their software independently
so I guess at this stage you're probably wondering if I love Nix OOS so much why don't I just go and
marry it it's not all roses there's no comparison between the sheer amount of packages you'll
find in Slackware or Debian or any other distro there's like a relatively small Nix community
who package things that they care about and it just so happens that for example there's no
GNOME there's no GNOME 2 or GNOME 3 there's quite a decent KDE there's XFCE there's like X Monat
and there's like loads of tiling window managers it's just whatever people are interested in and
happen to package so you may or may not find the software that you're interested in the good side
is it's not difficult to add packages for most packages if they've got a pretty typical build
system there's already quite an easy way basically you just have to you add the expression and it
just has to include a link to where you can download it from it also has to include a hash
so that it checks that it's like a checksum so that it checks that it has the correct
file and then if there's any yeah you have to list the
uh... build inputs which are the dependencies so that could include say qt or gtk or
whatever libraries the lib sound or whatever you want
whatever the package needs and you can add configuration options if you want people to be
able to tweak particular things and turn on and turn off things and yeah sometimes you will need
to adjust some of the make files or whatever our apply patches but typically you just add the
build inputs the dependencies for that software and that's usually will basically run the
um... configure make make install or if it's you know see make or whatever it's it's pretty sensible
in how it handles various things and if you do a pretty good job of most things you can just
drop them in i'm often surprised at how easy it is to to package things sometimes it's not
and you have to do manual changes so that's the thing i should really mention that nix isn't
such a recent project and elco visor actually released he presented a paper on it back in 2004
and it's been under development since then it's been a subject of quite a few research projects
in university of utrate in the Netherlands and that's one of the nice things about it as well as
that there's loads of research papers it's really been really in-depth not just documentation but
discussions of the computer science of how to manage deployment and upgrades and stuff so
it's really interesting i mean it's well worth reading the papers if that's if you're interested
in computer science in general even the nix domain specific language itself and how that works
and where it comes from and some of that stuff is really interesting i know there's a really good
interview with elco visor on software engineering radio as well where he discusses
grammars and things like that i should also point out that i am just an x user myself
i'm not a core contributor or anything like that i have a basic understanding of how it works
and i may have said many things which are not entirely correct or even completely wrong so
i hope i don't misrepresent it too much so anyway that's it that's nixos and the nix package manager
i hope it's of some interest i mean check it out if if there's something you want to install
the same i like to give kaden live as a good example because it can be quite tricky to compile
and we do have a binary version in nixos and nix packages so you could just install the
nix package manager which is may shortly be available in fedora actually and i think there's
i've seen it on the a war for arch and stuff so it might be very simple to install or otherwise
you can just compile it it's not very difficult to compile either and and then you just install
it nix n minus i and the name of the package and it should get it or you can click on the link
on hidra and dano did particular version and then you can update it as well via the nix package
manager so hopefully it's of some interest and yeah i'd be very curious to hear if people do give
this shot or if they have any feedback about it you know i i i do meet people who've like run debian
for whatever 20 years and they've never had a problem and they've never felt the need to update
anything and they're perfectly happy to wait for a few years or whatever or i don't mean that
and i'm condescending there i mean it's and you get this stable system and there's this massive
community and it works really well and that's nice so and i also met people who run arch and they
updated every day and they've never had any problems and everything works perfectly like that's
brilliant i i have not had this experience myself and as i say i've run a few different distros
and yeah nix os really gives me a lot of hope that you know this culture is possible where
everybody can continuously upgrade software and work on software and cherry pick whatever
dependencies they want for a particular piece of software and just get on with doing what they
enjoy and making cool stuff so that's it and thanks for listening and i hang out on our cast
planet if anyone wants to discuss this or if you want to do week i would love to do maybe a round
table we could discuss the merits and disadvantages are very approaches or whatever that would be
fun too so cool so take care and thanks for this
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