Toolbox is a tool for Linux operating systems, which allows the use of containerized command line environments. It is built on top of Podman and other standard container technologies from OCI.

This is particularly useful on OSTree based operating systems like Fedora CoreOS and Silverblue. The intention of these systems is to discourage installation of software on the host, and instead install software as (or in) containers — they mostly don't even have package managers like DNF or YUM. This makes it difficult to set up a development environment or install tools for debugging in the usual way.

Toolbox solves this problem by providing a fully mutable container within which one can install their favourite development and debugging tools, editors and SDKs. For example, it's possible to do yum install ansible without affecting the base operating system.

However, this tool doesn't require using an OSTree based system. It works equally well on Fedora Workstation and Server, and that's a useful way to incrementally adopt containerization.

The toolbox environment is based on an OCI image. On Fedora this is the fedora-toolbox image. This image is used to create a toolbox container that seamlessly integrates with the rest of the operating system by providing access to the user's home directory, the Wayland and X11 sockets, networking (including Avahi), removable devices (like USB sticks), systemd journal, SSH agent, D-Bus, ulimits, /dev and the udev database, etc..

Installation

Toolbox is installed by default on Fedora Silverblue. On other operating systems it's just a matter of installing the toolbox package.

Usage

Create your toolbox container:

[user@hostname ~]$ toolbox create
Created container: fedora-toolbox-33
Enter with: toolbox enter
[user@hostname ~]$

This will create a container called fedora-toolbox-<version-id>.

Enter the toolbox:

[user@hostname ~]$ toolbox enter
⬢[user@toolbox ~]$

Remove a toolbox container:

[user@hostname ~]$ toolbox rm fedora-toolbox-33
[user@hostname ~]$

Dependencies and Building

Toolbox requires at least Podman 1.4.0 to work, and uses the Meson build system.

The following dependencies are required to build it:

• meson
• go-md2man
• systemd
• go
• ninja
• patchelf

The following dependencies enable various optional features:

• bash-completion

It can be built and installed as any other typical Meson-based project:

[user@hostname toolbox]$ meson -Dprofile_dir=/etc/profile.d builddir
[user@hostname toolbox]$ ninja -C builddir
[user@hostname toolbox]$ sudo ninja -C builddir install

Toolbox is written in Go. Consult the src/go.mod file for a full list of all the Go dependencies.

By default, Toolbox uses Go modules and all the required Go packages are automatically downloaded as part of the build. There's no need to worry about the Go dependencies, unless the build environment doesn't have network access or any such peculiarities.

Distro support

By default, Toolbox creates the container using an OCI image called <ID>-toolbox:<VERSION-ID>, where <ID> and <VERSION-ID> are taken from the host's /usr/lib/os-release. For example, the default image on a Fedora 33 host would be fedora-toolbox:33.

This default can be overridden by the --image option in toolbox create, but operating system distributors should provide an adequately configured default image to ensure a smooth user experience.

Image requirements

Toolbox specifies the entry points of newly created containers in a certain way. It's best if the OCI image doesn't specify any entry point of its own to avoid interfering with the desired command line arguments. In other words, there shouldn't be any Entrypoint in the podman inspect output for the image. A wrong set of arguments will prevent toolbox enter from working.

If the image has a parent base image that does specify an entry point, then it can be reset with this Containerfile snippet:

ENTRYPOINT []

Toolbox customizes newly created containers in a certain way. This requires certain tools and paths to be present and have certain characteristics inside the OCI image.

Tools:

• capsh(1)
• mkdir(1)
• mount(8)
• passwd(1)
• test(1)
• touch(1)
• useradd(8)
• usermod(8)

Paths:

• /etc/host.conf: optional, if present not a bind mount
• /etc/hosts: optional, if present not a bind mount
• /etc/krb5.conf.d: directory, not a bind mount
• /etc/localtime: optional, if present not a bind mount
• /etc/machine-id: optional, not a bind mount
• /etc/resolv.conf: optional, if present not a bind mount
• /etc/timezone: optional, if present not a bind mount

Toolbox enables sudo(8) access inside containers. The following is necessary for that to work:

• The image should have sudo(8) enabled for users belonging to either the sudo or wheel groups, and the group itself should exist. File an issue if you really need support for a different group. However, it's preferable to keep this list as short as possible.

• The image should allow empty passwords for sudo(8). This can be achieved by either adding the nullok option to the PAM(8) configuration, or by add the NOPASSWD tag to the sudoers(5) configuration.

Since Toolbox only works with OCI images that fulfill certain requirements, it will refuse images that aren't tagged with com.github.containers.toolbox="true" and com.github.debarshiray.toolbox="true" labels. These labels are meant to be used by the maintainer of the image to indicate that they have read this document and tested that the image works with Toolbox. You can use the following snippet in a Containerfile for this:

LABEL com.github.containers.toolbox="true"

The label com.github.debarshiray.toolbox="true" was used in previous versions of toolbox but is currently deprecated.