You can distribute your Rust apps to many different Linux distributions using a MUSL-enabled version of Rust, with all the dependencies satisfied. However, end user discovery and update management remain a challenge.
Snaps fill this gap, letting you distribute a Rust app in an app store experience for end users.
Why are snaps good for Rust projects?
Snaps are easy to discover and install
Millions of users can browse and install snaps graphically in the Snap Store or from the command-line.
Snaps install and run the same across Linux
They bundle the exact versions of the tools you need, along with all of your app’s dependencies, be they modules or system libraries.
Snaps automatically update to the latest version
Four times a day, users’ systems will check for new versions and upgrade in the background.
Upgrades are not disruptive
Because upgrades are not in-place, users can keep your app open as it’s upgraded in the background.
Upgrades are safe
If your app fails to upgrade, users automatically roll back to the previous revision with data preserved.
Build a snap in 20 minutes
Ready to get started? By the end of this guide, you’ll understand how to make a snap of your app that can be published in the Snap Store, showcasing it to millions of Linux users.
For a brief overview of the snap creation process, including how to install snapcraft and how it’s used, see Snapcraft overview. For a more comprehensive breakdown of the steps involved, take a look at Creating a snap.
Snaps are defined in a single YAML file placed in the root folder of your project. The following example shows the entire snapcraft.yaml file for an existing project, XSV, leveraging the existing
Cargo.toml to satisfy runtime requirements. Don’t worry, we’ll break this down.
name: test-xsv version: git summary: A fast CSV command line toolkit written in Rust description: | xsv is a command line program for indexing, slicing, analysing, splitting and joining CSV files. Commands should be simple, fast and composable: - Simple tasks should be easy. - Performance trade offs should be exposed in the CLI interface. - Composition should not come at the expense of performance. base: core18 confinement: devmode parts: test-xsv: plugin: rust source: . apps: test-xsv: command: bin/xsv
snapcraft.yaml file starts with a small amount of human-readable metadata, which usually can be lifted from the GitHub description or project README.md. This data is used in the presentation of your app in the Snap Store.
name: test-xsv version: git summary: A fast CSV command line toolkit written in Rust description: | xsv is a command line program for indexing, slicing, analysing, splitting and joining CSV files. Commands should be simple, fast and composable: - Simple tasks should be easy. - Performance trade offs should be exposed in the CLI interface. - Composition should not come at the expense of performance.
name must be unique in the Snap Store. Valid snap names consist of lower-case alphanumeric characters and hyphens. They cannot be all numbers and they also cannot start or end with a hyphen.
git for the version, the current git tag or commit will be used as the version string. Versions carry no semantic meaning in snaps.
summary can not exceed 79 characters. You can use a chevron ‘>’ in the
description key to declare a multi-line description.
The base keyword defines a special kind of snap that provides a run-time environment with a minimal set of libraries that are common to most applications. They’re transparent to users, but they need to be considered, and specified, when building a snap.
To get started we won’t confine this application. Unconfined applications, specified with
devmode, can only be released to the hidden “edge” channel where you and other developers can install them.
Parts define what sources are needed to assemble your app. Parts can be anything: programs, libraries, or other needed assets, but for now, we’re only going to use one part: the xsv source code.
This example will also bundle the current stable release of Rust in the snap using Rustup, and you can define the exact version of Rust with the optional
- rust-revision: keyword, should you have specific requirements. Dependencies from your
Cargo.toml will also be bundled.
parts: test-xsv: plugin: rust source: .
For more details on Rust-specific metadata, see The Rust plugin.
Apps are the commands and services exposed to end users. If your Apps are the commands you want to expose to users and any background services your application provides. Each key under
apps is the command name that should be made available on users’ systems.
command specifies the path to the binary to be run. This is resolved relative to the root of your snap contents and automatically searches in the
bin sub directories of your snap.
apps: test-xsv: command: bin/xsv
If your command name matches the snap
name, users will be able run the command directly. If the names differ, then apps are prefixed with the snap
test-xsv.command-name, for example). This is to avoid conflicting with apps defined by other installed snaps.
If your application is intended to run as a service you simply add the line
daemon: simple after the command keyword. This will automatically keep the service running on install, update and reboot.
You can request an alias on the Snapcraft forum if your command name and snap name do not match but you don’t want your command prefixed. These aliases are set up automatically when your snap is installed from the Snap Store.
Building the snap
You can download the example repository with the following command:
$ git clone https://github.com/snapcraft-docs/xsv
After you’ve created the snapcraft.yaml, you can build the snap by simply executing the snapcraft command in the project directory:
$ snapcraft Using 'snapcraft.yaml': Project assets will be searched for from the 'snap' directory. Launching a VM. [...] Snapped test-xsv_0.13.0+git1.0728f0c-dirty_amd64.snap
The resulting snap can be installed locally. This requires the
--dangerous flag because the snap is not signed by the Snap Store. The
--devmode flag acknowledges that you are installing an unconfined application:
$ sudo snap install test-xsv_*.snap --devmode --dangerous
You can then try it out:
Removing the snap is simple too:
$ sudo snap remove test-xsv
You can also clean up the build environment, although this will slow down the next initial build:
$ snapcraft clean
By default, when you make a change to snapcraft.yaml, snapcraft only builds the parts that have changed. Cleaning a build, however, forces your snap to be rebuilt in a clean environment and will take longer.
Publishing your snap
To share your snaps you need to publish them in the Snap Store. First, create an account on the dashboard. Here you can customise how your snaps are presented, review your uploads and control publishing.
You’ll need to choose a unique “developer namespace” as part of the account creation process. This name will be visible by users and associated with your published snaps.
Make sure the
snapcraft command is authenticated using the email address attached to your Snap Store account:
$ snapcraft login
Reserve a name for your snap
You can publish your own version of a snap, provided you do so under a name you have rights to. You can register a name on dashboard.snapcraft.io, or by running the following command:
$ snapcraft register myrustsnap
Be sure to update the
name: in your
snapcraft.yaml to match this registered name, then run
Upload your snap
Use snapcraft to push the snap to the Snap Store.
$ snapcraft upload --release=edge myrustsnap_*.snap
If you’re happy with the result, you can commit the snapcraft.yaml to your GitHub repo and turn on automatic builds so any further commits automatically get released to edge, without requiring you to manually build locally.
Congratulations! You’ve just built and published your first Rust snap. For a more in-depth overview of the snap building process, see Creating a snap.