Posts tagged packaging


Safer Nix installation

:: linux, nix, packaging, sandbox, shell, system, test, testing, tutorial

By: Maciej Barć

Nix is useful for quickly testing out software and providing a strict environment that can be shared between people.

Today I’m trying out Nix again, this time I want to do it my way.

Installation process

Nix store

I know Nix needs “Nix store” installation on / (the system root).

Create it manually to prevent the installation script from calling sudo. 1st I switch to the root account, and then I run:

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mkdir -p -m 0755 /nix
chown -R xy:xy /nix

Running the install script

Download the Nix install script and examine the contents.

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curl -L https://nixos.org/nix/install > nix_install.sh

Then, run it with --no-daemon to prevent it running as system service.

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sh ./nix_install.sh --no-daemon
performing a single-user installation of Nix...
copying Nix to /nix/store...
installing 'nix-2.20.1'
building '/nix/store/1ahlg3bviy174d6ig1gn393c23sqlki6-user-environment.drv'...
unpacking channels...
modifying /home/xy/.bash_profile...
modifying /home/xy/.zshenv...
placing /home/xy/.config/fish/conf.d/nix.fish...

Installation finished!  To ensure that the necessary environment
variables are set, either log in again, or type

. /home/xy/.nix-profile/etc/profile.d/nix.fish

in your shell.

Wait!

modifying /home/xy/.bash_profile...
modifying /home/xy/.zshenv...
placing /home/xy/.config/fish/conf.d/nix.fish...

That’s very rude!

Stopping Nix from making a mess

I need to prevent Nix from mess up with my environment when I do not want it to. Nix puts some code into the Bash, ZSH and Fish initialization files during installation to ease it’s use. I do not want that since I do not want Nix to meddle with my environment without me knowing it.

I keep my .bash_profile and .zshenv in a stow-managed git repo so I can just cd into my repo and do git reset --hard, but for you will have to revert those files to their old forms manually.

Playing with Nix

We do not have nix in PATH but we still can launch it. Nix executables are located inside ~/.nix-profile/bin/.

By invoking nix-shell one can create a ephemeral environment containing only packages specified after the -p flag. I always add -p nix to have the Nix tools available also inside the spawned environment.

I will test out chibi (small Scheme interpreter) + rlwrap (REPL support for software lacking it) inside a Nix ephemeral environment:

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~/.nix-profile/bin/nix-shell -p nix chibi rlwrap

Inside the spawned shell:

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rlwrap chibi-scheme

In the chibi REPL, let’s see the contents of the PATH environment variable:

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(get-environment-variable "PATH")

And exit the Scheme REPL:

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(exit)

After the playtime, run garbage collection:

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~/.nix-profile/bin/nix-collect-garbage

.NET in Gentoo in 2023

:: dotnet, gentoo, packaging, portage, powershell

By: Maciej Barć

.NET ecosystem in Gentoo in year 2023

The Gentoo Dotnet project introduced better support for building .NET-based software using the nuget, dotnet-pkg-base and dotnet-pkg eclasses. This opened new opportunities of bringing new packages depending on .NET ecosystem to the official Gentoo ebuild repository and helping developers that use dotnet-sdk on Gentoo.

New software requiring .NET is constantly being added to the main Gentoo tree, among others that is:

  • PowerShell for Linux,
  • Denaro — finance application,
  • Ryujinx — NS emulator,
  • OpenRA — RTS engine for Command & Conquer, Red Alert and Dune2k,
  • Pinta — graphics program,
  • Pablodraw — Ansi, Ascii and RIPscrip art editor,
  • Dafny — verification-aware programming language
  • many packages aimed straight at developing .NET projects.

Dotnet project is also looking for new maintainers and users who are willing to help out here and there. Current state of .NET in Gentoo is very good but we can still do a lot better.

Special thanks to people who helped out

ELisp ebuilds good practices

:: elisp, emacs, gentoo, lisp, packaging

By: Maciej Barć

Check load path

Some Elisp package compilation failures are caused by not setting the loadpath correctly. It mostly happens when you compile source from a directory that is not the current working directory. For example:

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elisp-compile elisp/*.el

In most cases you can cd or override the S variable to set it to location where ELisp source resides.

But in other cases you can append to load path the directory with source, see:

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BYTECOMPFLAGS="${BYTECOMPFLAGS} -L elisp" elisp-compile elisp/*.el

Do not rename auto-generated autoload file

elisp-make-autoload-file allows to name the generated autoload file. For sake of easier debugging and writing Gentoo SITEFILEs, please do not rename the generated file.

The name of that file should always be ${PN}-autoloads.el.

Use new elisp-enable-tests function

elisp-enable-tests allows to set up IUSE, RESTRICT, BDEPEND and the test runner function for running tests with the specified test runner.

The 1st (test-runner) argument must be one of:

  • buttercup — for buttercup provided via app-emacs/buttercup,
  • ert-runner — for ert-runner provided via app-emacs/ert-runner,
  • ert — for ERT, the built-in GNU Emacs test utility.

The 2nd argument is the directory where test are located, the leftover arguments are passed to the selected test runner.

Example:

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EAPI=8

inherit elisp

# Other package settings ...

SITEFILE="50${PN}-gentoo.el"
DOCS=( README.md )

elisp-enable-tests buttercup test

Remove empty SITEFILEs

Recently a feature was added to elisp.eclass that will cause build process to generate the required SITEFILE with boilerplate code if it does not exist.

So if your SITEFILE looked like this:

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(add-to-list 'load-path "@SITELISP@")

… then, you can just remove that file.

But remember to keep the SITEFILE variable inside your ebuild:

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SITEFILE="50${PN}-gentoo.el"

Remove pkg.el files

The *-pkg.el files are useless to Gentoo distribution model of Emacs Lisp packages and should be removed. It is as simple as adding this line to a ebuild:

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ELISP_REMOVE="${PN}-pkg.el"

Beware that some packages will try to find their ${PN}-pkg.el file, but in most cases this will show up in failing package tests.

Use official repository

It is tedious to repackage Elpa tarballs, so use the official upstream even if you have to snapshot a specific commit.

To snapshot GitHub repos you would generally use this code:

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# First check if we have the correct version to prevent
# autobumping package version without changing the commit.
[[ ${PV} == *_p20220325 ]] && COMMIT=65c496d3d1d1298345beb9845840067bffb2ffd8

# Use correct URL that supports snapshots.
SRC_URI="https://github.com/domtronn/${PN}/archive/${COMMIT}.tar.gz
    -> ${P}.tar.gz"

# Override the temporary build directory variable.
S="${WORKDIR}"/${PN}-${COMMIT}

Include live version support

We do not want to be worse than the Melpa unstable :D

So, why not allow the given package to be used live?

Even if you do not push the live package to the overlay, please include support for it.

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if [[ ${PV} == *9999* ]] ; then
    inherit git-r3
    EGIT_REPO_URI="https://github.com/example/${PN}.git"
else
    SRC_URI="https://github.com/example/${PN}/archive/${PV}.tar.gz
        -> ${P}.tar.gz"
    KEYWORDS="~amd64 ~x86"
fi

Ask for tags

Git is good, git tags are good. In case if upstream does not tag their package or just forgets to, kindly ask them to create a git tag when bumping Emacs package versions.

Installing PowerShell modules via Portage

:: dotnet, gentoo, packaging, portage, powershell

By: Maciej Barć

Building PowerShell

As a part of my work of modernizing the way .NET SDK packages are distributed in Gentoo I delved into packaging a from-source build of PowerShell for Gentoo using the dotnet-pkg eclass.

Packaging pwsh was a little tricky but I got a lot of help from reading the Alpine Linux’s APKBUILD. I had to generate special C# code bindings with ResGen and repackage the PowerShell tarball. Other than this trick, restoring and building PowerShell was pretty straight forward with the NuGet package management support from the dotnet-pkg.eclass.

Alternatively if you do not want to build PowerShell you can install the binary package, I have in plans to keep that package around even after we get the non-binary app-shells/pwsh into the official Gentoo ebuild repository.

Why install modules via Portage?

But why stop on PowerShell when we can also package multiple PS modules?

Installing modules via Portage has many benefits:

  • better version control,
  • more control over global install,
  • no need to enable PS Gallery,
  • sandboxed builds,
  • using system .NET runtime.

Merging the modules

PowerShell’s method of finding modules is at follows: check paths from the PSModulePath environment variable for directories containing valid .psd1 files which define the PS modules.

By default pwsh tries to find modules in paths:

  • user’s modules directory — ~/.local/share/powershell/Modules
  • system modules directory in /usr/local/usr/local/share/powershell/Modules
  • Modules directory inside the pwsh home — for example /usr/share/pwsh-7.3/Modules

Because we do not want to touch either /usr/local nor pwsh home, we embed a special environment variable inside the pwsh launcher script to extend the path where pwsh looks for PS modules. The new module directory is located at /usr/share/GentooPowerShell/Modules.

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dotnet-pkg-utils_append_launchervar \
    'PSModulePath="${PSModulePath}:/usr/share/GentooPowerShell/Modules:"'

So every PowerShell module will install it’s files inside /usr/share/GentooPowerShell/Modules.

To follow PS module location convention we add to that path a segment for the real module name and a segment for module version. This also enables us to have proper multi-slotting because most of the time the modules will not block installing other versions.

Take a look at this example from the app-pwsh/posh-dotnet–1.2.3 ebuild:

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src_install() {
    insinto /usr/share/GentooPowerShell/Modules/${PN}/${PV}
    doins ${PN}.psd1 ${PN}.psm1

    einstalldocs
}

And that is it. Some packages do not even need to be compiled, they just need files placed into specific location. But when compilation of C# code is needed we have dotnet-pkg to help.

Binary packages in Gentoo

:: binary packages, gentoo, packaging, portage, system

By: Maciej Barć

Binpkgs generated by user

The binary packages generated by user can have architecture-specific optimizations because they are generated after they were compiled by the host Portage installation.

In addition binpkgs are generated from ebuilds so if there is a USE flag incompatibility on the consumer system then the binpkg will not be installed on the host and Portage will fall back to from-source compilation.

Those binary packages can use two formats: XPAK and GPKG.

XPAK had many issues and is getting superseded by the GPKG format. Beware of upcoming GPKG transition and if you must use XPAKs then you should explicitly enable it in your system’s Portage configuration.

To host a binary package distribution server see the Binary package guide on the Gentoo wiki.

Bin packages in a repository

Binary packages in ::gentoo (the official Gentoo repository) have the -bin suffix.

Those packages might have USE flags but generally they are very limited in case of customizations or code optimizations because they were compiled either by a Gentoo developer or by a given package upstream maintainer (or their CI/CD system).

Those packages land in ::gentoo mostly because it is too hard (or even impossible) to compile them natively by Portage. Most of the time those packages use very complicated build systems or do not play nice with network sandbox like (e.g. Scala-based projects) or use very large frameworks/libraries like (e.g. Electron).

They can also be added to the repository because they are very desirable either by normal users (e.g. www-client/firefox-bin) or for (from-source) package bootstrapping purposes (e.g. dev-java/openjdk-bin). Such packages are sometimes generated from the regular source packages inside ::gentoo and later repackaged.