swiftly is a CLI tool for installing, managing, and switching between Swift toolchains, written in Swift. swiftly itself is designed to be extremely easy to install and get running, and its command interface is intended to be flexible while also being simple to use. The overall experience is inspired by and meant to feel reminiscent of the Rust toolchain manager rustup.

Ongoing maintenance and stewardship of this project is led by the SSWG.

To download swiftly and install Swift, run the following in your terminal, then follow the on-screen instructions.

curl -L https://raw.githubusercontent.com/swift-server/swiftly/main/install/swiftly-install.sh | bash

$ swiftly install latest

Fetching the latest stable Swift release...
Installing Swift 5.6.3
Downloaded 488.5 MiB of 488.5 MiB
Extracting toolchain...
Swift 5.6.3 installed successfully!

$ swift --version

Swift version 5.6.3 (swift-5.6.3-RELEASE)
Target: x86_64-unknown-linux-gnu

• Installing multiple toolchains, including both stable releases and snapshots
• Switching which installed toolchain is active (i.e. which one is discovered via $PATH)
• Updating installed toolchains to the latest available versions of those toolchains (not yet implemented)
• Uninstalling installed toolchains
• Listing the toolchains that are available to install (not yet implemented)

• Linux-based platforms listed on https://swift.org/download
  • CentOS 7 will not be supported due to some dependencies of swiftly not supporting it, however.

Right now, swiftly is in the very early stages of development and is working towards an MVP for the Linux. Once that is complete, work will begin on an MVP for macOS. For more detailed information about swiftly's intended features and implementation, check out the design document.

$ swiftly install latest

A specific version of Swift can be provided to the install command.

$ swiftly install 5.6.1

If a patch version isn't specified, swiftly will look up and install the latest patch version that matches the minor version provided:

$ swiftly install 5.6

$ swiftly install main-snapshot-2022-01-28

If the date isn't specified, swiftly will look up and install the latest available snapshot:

$ swiftly install main-snapshot

$ swiftly install 5.7-snapshot-2022-08-30

If the date isn't specified, swiftly will look up and install the latest snapshot associated with the provided development branch:

$ swiftly install 5.7-snapshot

$ swiftly uninstall 5.6.3

To uninstall all toolchains associated with a given minor release, leave off the patch version:

$ swiftly uninstall 5.6

$ swiftly uninstall main-snapshot-2022-08-30
$ swiftly uninstall 5.7-snapshot-2022-08-30

To uninstall all snapshots associated with a given branch (either main or a release branch), omit the date:

$ swiftly uninstall main-snapshot
$ swiftly uninstall 5.7-snapshot

The list command prints all the toolchains installed by swiftly:

$ swiftly list

“Using” a toolchain sets it as the active toolchain, meaning it will be the one found via $PATH and invoked via swift commands executed in the shell.

To use the toolchain associated with the most up-to-date Swift version, the “latest” version can be specified:

$ swiftly use latest

To use a specific stable version of Swift already installed, specify the major/minor/patch version:

$ swiftly use 5.3.1

To use the latest installed patch version associated with a given major/minor version pair, the patch can be omitted:

$ swiftly use 5.3

To use a specific snapshot version, specify the full snapshot version name:

$ swiftly use 5.3-snapshot-YYYY-MM-DD

To use the latest installed snapshot associated with a given version, the date can be omitted:

$ swiftly use 5.3-snapshot

To use a specific main snapshot, specify the full snapshot version name:

$ swiftly use main-snapshot-YYYY-MM-DD

To use the latest installed main snapshot, leave off the date:

$ swiftly use main-snapshot

Update replaces a given toolchain with a later version of that toolchain. For a stable release, this means updating to a later patch version. For snapshots, this means updating to the most recently available snapshot.

If no version is provided, update will update the currently selected toolchain to its latest version while removing the old version. The newly installed version will be used.

Note that this command isn't implemented yet, but it will be included in a future release.

$ swiftly update

To update the latest installed stable version, the “latest” version can be provided:

swiftly update latest

To update to the latest patch release of a given major/minor version, only the major/minor pair need to be provided. This will update the latest installed toolchain associated with that major/minor version to the latest patch release for that major/minor version.

swiftly update 5.3

You can also specify a full version to update that toolchain to the latest patch available for that major/minor version:

swiftly update 5.3.1

Similarly, to update the latest snapshot associated with a specific version, the “a.b-snapshot” version can be supplied:

swiftly update 5.3-snapshot

You can also update the latest installed main snapshot to the latest available one by just providing main-snapshot:

swiftly update main-snapshot

The list-available command can be used to list the latest toolchains that Apple has made available to install.

Note that this command isn't implemented yet, but it will be included in a future release.

swiftly list-available

A selector can optionally be provided to narrow down the results:

$ swiftly list-available 5.6
$ swiftly list-available main-snapshot
$ swiftly list-available 5.7-snapshot

This command checks to see if there are new versions of swiftly itself and upgrades to them if so.

Note that this command isn't implemented yet, but it will be included in a future release.

swiftly self-update

The canonical name for a snapshot toolchain in swiftly's command interface is the following:

<branch>-snapshot-YYYY-MM-DD

However, swiftly also accepts the snapshot toolchain filenames from the downloads provided by swift.org. For example:

swift-DEVELOPMENT-SNAPSHOT-2022-09-10-a
swift-5.7-DEVELOPMENT-SNAPSHOT-2022-08-30-a

The canonical name format was chosen to reduce the keystrokes needed to refer to a snapshot toolchain, but the longer form is also useful when copy/pasting a toolchain name provided from somewhere else.

swiftly currently uses the GitHub API to look up the available Swift toolchains. To avoid running up against rate limits, you can provide a GitHub access token via the --token option (the token doesn't need any permissions):

$ swiftly install latest --token <GitHub authentication token>

Swift.org currently provides experimental .rpm and .deb packages that allow you to install Swift via your package manager. While these are an effective way to install and update a single version of Swift, they aren't well suited to the task of installing multiple Swift toolchains that you can easily switch between. swiftly's target audience are Swift developers that switch between versions for the purposes of testing their libraries and applications. The .deb and .rpm also currently don't provide support for snapshot toolchains.

swiftenv is an existing Swift version manager which already has much of the functionality that swiftly will eventually have. It's an awesome tool, and if it's part of your workflow then we encourage you to keep using it! That said, swiftly is/will be different a few ways:

• swiftly is being built as a community driven effort led by the Swift server workgroup, and through this collaboration, swiftly will eventually become an official installation tool for Swift toolchains. As first step towards that, swiftly will help inform the creation of API endpoints maintained by the Swift project that it will use to retrieve information about what toolchains are available to install and to verify their expected signatures. swiftenv currently uses a third party API layer for this. Using an official API reduces the avenues for security vulnerabilities and also reduces the risk of downtime affecting Swift installations. Note that this is planned for the future--swiftly currently uses the GitHub API for this purpose.

• swiftly will be written in Swift, which we think is important for maintainability and encouraging community contributions.

• swiftly has first-class support for installing and managing snapshot toolchains.

• swiftly has built in support for updating toolchains.

• swiftly is optimized for ease of installation. Ideally, this will be done with a bash one-liner similar to Homebrew and rustup. In addition, swiftly won't require any system dependencies to be installed on the user's system. While swiftenv is also relatively easy to install, it does involve cloning a git repository or using Homebrew, and it requires a few system dependencies (e.g. bash, curl, tar).