7.3 Invocando guix pack

Occasionally you want to pass software to people who are not (yet!) lucky enough to be using Guix. You’d tell them to run guix package -i something, but that’s not possible in this case. This is where guix pack comes in.

Nota: If you are looking for ways to exchange binaries among machines that already run Guix, veja Invocando guix copy, Invocando guix publish, and Invocando guix archive.

The guix pack command creates a shrink-wrapped pack or software bundle: it creates a tarball or some other archive containing the binaries of the software you’re interested in, and all its dependencies. The resulting archive can be used on any machine that does not have Guix, and people can run the exact same binaries as those you have with Guix. The pack itself is created in a bit-reproducible fashion, so anyone can verify that it really contains the build results that you pretend to be shipping.

For example, to create a bundle containing Guile, Emacs, Geiser, and all their dependencies, you can run:

$ guix pack guile emacs emacs-geiser
…
/gnu/store/…-pack.tar.gz

The result here is a tarball containing a /gnu/store directory with all the relevant packages. The resulting tarball contains a profile with the three packages of interest; the profile is the same as would be created by guix package -i. It is this mechanism that is used to create Guix’s own standalone binary tarball (veja Instalação de binários).

Users of this pack would have to run /gnu/store/…-profile/bin/guile to run Guile, which you may find inconvenient. To work around it, you can create, say, a /opt/gnu/bin symlink to the profile:

guix pack -S /opt/gnu/bin=bin guile emacs emacs-geiser

That way, users can happily type /opt/gnu/bin/guile and enjoy.

What if the recipient of your pack does not have root privileges on their machine, and thus cannot unpack it in the root file system? In that case, you will want to use the --relocatable option (see below). This option produces relocatable binaries, meaning they can be placed anywhere in the file system hierarchy: in the example above, users can unpack your tarball in their home directory and directly run ./opt/gnu/bin/guile.

Alternatively, you can produce a pack in the Docker image format using the following command:

guix pack -f docker -S /bin=bin guile guile-readline

The result is a tarball that can be passed to the docker load command, followed by docker run:

docker load < file
docker run -ti guile-guile-readline /bin/guile

where file is the image returned by guix pack, and guile-guile-readline is its “image tag”. See the Docker documentation for more information.

Yet another option is to produce a SquashFS image with the following command:

guix pack -f squashfs bash guile emacs emacs-geiser

The result is a SquashFS file system image that can either be mounted or directly be used as a file system container image with the Singularity container execution environment, using commands like singularity shell or singularity exec.

Several command-line options allow you to customize your pack:

--format=format

-f format

Produce a pack in the given format.

The available formats are:

tarball

This is the default format. It produces a tarball containing all the specified binaries and symlinks.

docker

This produces a tarball that follows the Docker Image Specification. By default, the “repository name” as it appears in the output of the docker images command is computed from package names passed on the command line or in the manifest file. Alternatively, the “repository name” can also be configured via the --image-tag option. Refer to --help-docker-format for more information on such advanced options.

squashfs

This produces a SquashFS image containing all the specified binaries and symlinks, as well as empty mount points for virtual file systems like procfs.

Nota: Singularity requires you to provide /bin/sh in the image. For that reason, guix pack -f squashfs always implies -S /bin=bin. Thus, your guix pack invocation must always start with something like:

guix pack -f squashfs bash …

If you forget the bash (or similar) package, singularity run and singularity exec will fail with an unhelpful “no such file or directory” message.

deb ¶

This produces a Debian archive (a package with the ‘.deb’ file extension) containing all the specified binaries and symbolic links, that can be installed on top of any dpkg-based GNU(/Linux) distribution. Advanced options can be revealed via the --help-deb-format option. They allow embedding control files for more fine-grained control, such as activating specific triggers or providing a maintainer configure script to run arbitrary setup code upon installation.

guix pack -f deb -C xz -S /usr/bin/hello=bin/hello hello

Nota: Because archives produced with guix pack contain a collection of store items and because each dpkg package must not have conflicting files, in practice that means you likely won’t be able to install more than one such archive on a given system. You can nonetheless pack as many Guix packages as you want in one such archive.

Aviso: dpkg will assume ownership of any files contained in the pack that it does not know about. It is unwise to install Guix-produced ‘.deb’ files on a system where /gnu/store is shared by other software, such as a Guix installation or other, non-deb packs.

rpm ¶

This produces an RPM archive (a package with the ‘.rpm’ file extension) containing all the specified binaries and symbolic links, that can be installed on top of any RPM-based GNU/Linux distribution. The RPM format embeds checksums for every file it contains, which the rpm command uses to validate the integrity of the archive.

Advanced RPM-related options are revealed via the --help-rpm-format option. These options allow embedding maintainer scripts that can run before or after the installation of the RPM archive, for example.

The RPM format supports relocatable packages via the --prefix option of the rpm command, which can be handy to install an RPM package to a specific prefix.

guix pack -f rpm -R -C xz -S /usr/bin/hello=bin/hello hello

sudo rpm --install --prefix=/opt /gnu/store/...-hello.rpm

Nota: Contrary to Debian packages, conflicting but identical files in RPM packages can be installed simultaneously, which means multiple guix pack-produced RPM packages can usually be installed side by side without any problem.

Aviso: rpm assumes ownership of any files contained in the pack, which means it will remove /gnu/store upon uninstalling a Guix-generated RPM package, unless the RPM package was installed with the --prefix option of the rpm command. It is unwise to install Guix-produced ‘.rpm’ packages on a system where /gnu/store is shared by other software, such as a Guix installation or other, non-rpm packs.

--relocatable

-R

Produce relocatable binaries—i.e., binaries that can be placed anywhere in the file system hierarchy and run from there.

When this option is passed once, the resulting binaries require support for user namespaces in the kernel Linux; when passed twice¹⁸, relocatable binaries fall to back to other techniques if user namespaces are unavailable, and essentially work anywhere—see below for the implications.

For example, if you create a pack containing Bash with:

guix pack -RR -S /mybin=bin bash

... you can copy that pack to a machine that lacks Guix, and from your home directory as a normal user, run:

tar xf pack.tar.gz
./mybin/sh

In that shell, if you type ls /gnu/store, you’ll notice that /gnu/store shows up and contains all the dependencies of bash, even though the machine actually lacks /gnu/store altogether! That is probably the simplest way to deploy Guix-built software on a non-Guix machine.

Nota: By default, relocatable binaries rely on the user namespace feature of the kernel Linux, which allows unprivileged users to mount or change root. Old versions of Linux did not support it, and some GNU/Linux distributions turn it off.

To produce relocatable binaries that work even in the absence of user namespaces, pass --relocatable or -R twice. In that case, binaries will try user namespace support and fall back to another execution engine if user namespaces are not supported. The following execution engines are supported:

default

Try user namespaces and fall back to PRoot if user namespaces are not supported (see below).

performance

Try user namespaces and fall back to Fakechroot if user namespaces are not supported (see below).

userns

Run the program through user namespaces and abort if they are not supported.

proot

Run through PRoot. The PRoot program provides the necessary support for file system virtualization. It achieves that by using the ptrace system call on the running program. This approach has the advantage to work without requiring special kernel support, but it incurs run-time overhead every time a system call is made.

fakechroot

Run through Fakechroot. Fakechroot virtualizes file system accesses by intercepting calls to C library functions such as open, stat, exec, and so on. Unlike PRoot, it incurs very little overhead. However, it does not always work: for example, some file system accesses made from within the C library are not intercepted, and file system accesses made via direct syscalls are not intercepted either, leading to erratic behavior.

When running a wrapped program, you can explicitly request one of the execution engines listed above by setting the GUIX_EXECUTION_ENGINE environment variable accordingly.

--entry-point=command

Use command as the entry point of the resulting pack, if the pack format supports it—currently docker and squashfs (Singularity) support it. command must be relative to the profile contained in the pack.

The entry point specifies the command that tools like docker run or singularity run automatically start by default. For example, you can do:

guix pack -f docker --entry-point=bin/guile guile

The resulting pack can easily be loaded and docker run with no extra arguments will spawn bin/guile:

docker load -i pack.tar.gz
docker run image-id

--entry-point-argument=command

-A command

Use command as an argument to entry point of the resulting pack. This option is only valid in conjunction with --entry-point and can appear multiple times on the command line.

guix pack -f docker --entry-point=bin/guile --entry-point-argument="--help" guile

--max-layers=n

Specifies the maximum number of Docker image layers allowed when building an image.

guix pack -f docker --max-layers=100 guile

This option allows you to limit the number of layers in a Docker image. Docker images are comprised of multiple layers, and each layer adds to the overall size and complexity of the image. By setting a maximum number of layers, you can control the following effects:

• Disk Usage: Increasing the number of layers can help optimize the disk space required to store multiple images built with a similar package graph.
• Pulling: When transferring images between different nodes or systems, having more layers can reduce the time required to pull the image.

--expression=expr

-e expr

Consider the package expr evaluates to.

This has the same purpose as the same-named option in guix build (veja --expression in guix build).

--manifest=arquivo

-m arquivo

Use the packages contained in the manifest object returned by the Scheme code in file. This option can be repeated several times, in which case the manifests are concatenated.

This has a similar purpose as the same-named option in guix package (veja --manifest) and uses the same manifest files. It allows you to define a collection of packages once and use it both for creating profiles and for creating archives for use on machines that do not have Guix installed. Note that you can specify either a manifest file or a list of packages, but not both.

Veja Escrevendo manifestos, for information on how to write a manifest. Veja guix shell --export-manifest, for information on how to “convert” command-line options into a manifest.

--system=system

-s sistema

Attempt to build for system—e.g., i686-linux—instead of the system type of the build host.

--target=triplet ¶

Cross-build for triplet, which must be a valid GNU triplet, such as "aarch64-linux-gnu" (veja GNU configuration triplets em Autoconf).

--compression=tool

-C tool

Compress the resulting tarball using tool—one of gzip, zstd, bzip2, xz, lzip, or none for no compression.

--symlink=spec

-S spec

Add the symlinks specified by spec to the pack. This option can appear several times.

spec has the form source=target, where source is the symlink that will be created and target is the symlink target.

For instance, -S /opt/gnu/bin=bin creates a /opt/gnu/bin symlink pointing to the bin sub-directory of the profile.

--save-provenance

Save provenance information for the packages passed on the command line. Provenance information includes the URL and commit of the channels in use (veja Canais).

Provenance information is saved in the /gnu/store/…-profile/manifest file in the pack, along with the usual package metadata—the name and version of each package, their propagated inputs, and so on. It is useful information to the recipient of the pack, who then knows how the pack was (supposedly) obtained.

This option is not enabled by default because, like timestamps, provenance information contributes nothing to the build process. In other words, there is an infinity of channel URLs and commit IDs that can lead to the same pack. Recording such “silent” metadata in the output thus potentially breaks the source-to-binary bitwise reproducibility property.

--root=arquivo ¶

-r arquivo

Make file a symlink to the resulting pack, and register it as a garbage collector root.

--localstatedir

--profile-name=name

Include the “local state directory”, /var/guix, in the resulting pack, and notably the /var/guix/profiles/per-user/root/name profile—by default name is guix-profile, which corresponds to ~root/.guix-profile.

/var/guix contains the store database (veja O armazém) as well as garbage-collector roots (veja Invocando guix gc). Providing it in the pack means that the store is “complete” and manageable by Guix; not providing it pack means that the store is “dead”: items cannot be added to it or removed from it after extraction of the pack.

One use case for this is the Guix self-contained binary tarball (veja Instalação de binários).

--derivation

-d

Print the name of the derivation that builds the pack.

--bootstrap

Use the bootstrap binaries to build the pack. This option is only useful to Guix developers.

In addition, guix pack supports all the common build options (veja Opções de compilação comum) and all the package transformation options (veja Opções de transformação de pacote).