guix on gentoo howto

February 11, 2017

TL;DR

Getting guix on gentoo (same steps):

install guix from gentoo main tree: emerge guix
enable guix-daemon service:
- on systemd: systemctl enable guix-daemon
- on openrc: rc-update add guix-daemon

create a profile symlink and set some environment variables:

# profiles and PATH
$ ln -sf /var/guix/profiles/per-user/$USER/guix-profile $HOME/.guix-profile
$ export PATH="${HOME}/.guix-profile/bin:${HOME}/.guix-profile/sbin${PATH:+:}$PATH"

# gnutls certs
$ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
$ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
$ export GIT_SSL_CAINFO="$SSL_CERT_FILE"

# libc locales
$ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale

Ready!

More commands

install a package: guix package -i icecat
uninstall a package: guix package -r icecat
start a new shell with only specified package(s) in environment: guix environment --ad-hoc --pure icecat

Some words on guix

Guix has the same underlying storage model as nix: package descriptions fully capture environment of inputs to get reproducible build result of built artifact. They are also called derivations.

Commandline interface is slightly different from nix: to me it feels more consistent and more powerful. For example nix provides tools like nix-build, nix-env, nix-collect-garbage, nix-store, nix-shell. While guix provides single entry point guix command.

guix environment (sibling of nix-shell) allows you to create an isolated shell and optionally run it in a separate container. That provides additional isolation layer on foreign distros (I run gentoo).

Example comparison to get ghc in isolated environment:

# get only 'ghc' into environemnt
$ nix-shell --pure -p ghc


# same but for guix
$ guix environment --ad-hoc ghc
[sf] ~:echo /bin/a*
/bin/attr /bin/awk

# same as above but in container
$ guix environment --ad-hoc --container ghc
slyfox@sf ~ [env]# echo /bin/a*
/bin/a*

Here container mode allows us to hide all specifics of a host system. It gives me more confidence that nothing from my host system leaks into guix-built packages.

Let’s look at an example guix package. One of tools missing in guix repos was re2c. I’ve dumped the following into current directory:

; cat ~/.guix/re2c.scm
(use-modules (guix)
             (guix build-system gnu)
             (guix licenses))

(package
  (name "re2c")
  (version "0.15")
  (source (origin
           (method url-fetch)
           (uri (string-append "https://github.com/skvadrik/" name
                               "/releases/download/" version "/"
                               name "-" version ".tar.gz"))
           (sha256
            (base32
             ; got as: guix download https://github.com/skvadrik/re2c/releases/download/0.15/re2c-0.15.tar.gz
             "1kdfjs6jb1d4rymk8aqr3l775jx6hl8ml9wpv3q23i2vyfxnnsas"))))
  (build-system gnu-build-system)
  (home-page "http://re2c.org/")
  (synopsis "Lexer generator for C/C++")
  (description
   "@code{re2c} generates minimalistic ...")
  (license public-domain))

Tried to build the package:

$ guix build -f re2c.scm re2c
substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
@ build-started /gnu/store/1nwww0i3cgp59yyc0r9wsg98ynmj6dq8-re2c-0.15.drv - x86_64-linux /var/log/guix/drvs/1n//www0i3cgp59yyc0r9wsg98ynmj6dq8-re2c-0.15.drv.bz2
starting phase `set-SOURCE-DATE-EPOCH'
...
phase `compress-documentation' succeeded after 0.0 seconds
@ build-succeeded /gnu/store/1nwww0i3cgp59yyc0r9wsg98ynmj6dq8-re2c-0.15.drv -
/gnu/store/8mcnjdismqmg25ds9jg7rf6ay3vwlqxr-re2c-0.16
/gnu/store/wfmj24p5y3xva5jrc8rrk25z9zf6ssvx-re2c-0.15

Done!

We can install built package with guix package -f re2c.scm -i re2c or run it in isolated environment: guix environment -l re2c.scm --ad-hoc -C re2c

The package was added upstream in this form

Once package got accepted into guix tree everyone is able to get it with mere guix pull.

We can verify that local build matches hydra build:

$ guix build --check re2c
...
/gnu/store/8mcnjdismqmg25ds9jg7rf6ay3vwlqxr-re2c-0.16

No errors so far.

Or check size of runtime dependencies:

$ guix size re2c
store item                                                       total    self
/gnu/store/8mcnjdismqmg25ds9jg7rf6ay3vwlqxr-re2c-0.16               61.4     0.4   0.6%
/gnu/store/cdi08kw7r6r684w8mk0xq0dkgpjhfpmd-gcc-4.9.4-lib           61.0    22.7  37.0%
/gnu/store/iwgi9001dmmihrjg4rqhd6pa6788prjw-glibc-2.24              38.3    36.8  60.0%
/gnu/store/rvgmixpmsq5lqr9qflhkm70kg7a4rys2-bash-static-4.4.0        1.4     1.4   2.3%
total: 61.4 MiB

Another useful feature is to get build logs on hydra. Say, how did build look like on arm? Easy:

$ guix build --log-file re2c --system=armhf-linux
substitute: updating list of substitutes from 'https://mirror.hydra.gnu.org'... 100.0%
https://mirror.hydra.gnu.org/log/j6hlxb9bbvi8wvjcxj8mswkcdkjy8kc8-re2c-0.16
...
configure flags: ("CONFIG_SHELL=/gnu/store/dbsflrccll1laf2q0asr6gl995b9p7y7-bash-4.4.0/bin/bash" "SHELL=/gnu/store/dbsflrccll1laf2q0asr6gl995b9p7y7-bash-4.4.0/bin/bash" "--prefix=/gnu/store/j6hlxb9bbvi8wvjcxj8mswkcdkjy8kc8-re2c-0.16" "--enable-fast-install" "--build=arm-unknown-linux-gnueabihf")
...
checking size of char... 1
checking size of short... 2
checking size of int... 4
checking size of long... 4
checking size of long long... 8
checking size of __int64... 0
checking size of void *... 4
checking size of 0l... 4
checking size of 0ll... 8
checking size of 0i8... 0

Looks like arm :)

There is many more interesting topics in guix user manual: https://www.gnu.org/software/guix/manual/

Some of them are:

visualise dependency graphs with guix graph
check for problems in packages (including known vulnerabilities) with guix lint
importing packages from other systems like cpan, hackage, nix and others
checking for upstream updates of known packages with guix refresh
bootstrapping of a new architecture or OS

Have fun!