Swift Continuous Integration

The Swift project follows an incremental development model, and utilizes continuous integration (CI) testing of changes in pull requests before merging as a core tool for maintaining project stability. The system produces the snapshot builds posted on swift.org, and runs tests against active branches. It is also used as part of the review process to run tests against pull requests before committing them.


Our continuous integration system is powered by Jenkins and currently supports building and testing on macOS, Ubuntu 16.04, and Ubuntu 18.04. Testing on the iOS simulator is also supported.

Currently, there are 58 macOS nodes, running macOS 10.13.5, and building with Xcode 10 beta 6. There are also 20 Linux nodes, running Ubuntu 14.04, Ubuntu 16.04 and Ubuntu 18.04.

Job organization

Continuous integration jobs are organized within the CI system in the following categories:

Job Configuration

Job OS Build Type
Swift Incremental macOS 
Ubuntu 14.04
Ubuntu 16.04
Ubuntu 18.04
LLDB Incremental macOS 
Ubuntu 14.04
Ubuntu 16.04
Ubuntu 18.04
Swift (Tools Opts+Assert, Stdlib DebugInfo+Assert, Test Simulator) macOS Clean
Swift (Tools Opts+Assert, Stdlib Opt+DebugInfo+Assert, Test Simulator) macOS Clean
Swift (Tools Opts+Assert, Stdlib Opt+DebugInfo, Test Simulator) macOS Clean

The build script command is listed in the description for each job. Most build script commands use a build system preset in the command which contains further build and test settings. Documentation of the presets is contained in the build script source.


There are several ways in which you can interact with the swift.org CI system:

Pull Request Testing

When a change is reviewed on a pull request, a member of the Swift team will trigger testing by the CI system. Tests can be triggered to run on macOS, Linux, or both platforms.

pull request CI trigger

Testing status is then posted inline with the pull request, showing that a test is in progress. You can click the “details” link to go directly to the status page for the test in progress. CI Progress

When tests complete, that result is also updated in the pull request CI Pass

If there are issues found during testing, you will get a link to the details of the failure. CI Pass

It is expected that changes meet the quality standards for the Swift project before they are committed to the development branch, and you are responsible for fixing problems found by your changes. If your changes break builds or tests on the development or release branches, you will receive email notification.

Community Involvement

The Swift project welcomes proposals from the community for adding support for other configurations.

Swift Community-Hosted Continuous Integration

Community members can volunteer to host nodes for additional platforms on Swift Community-Hosted Continuous Integration, and are responsible for maintaining the host system. New nodes can be initiated by creating a pull request at: Swift Community-Hosted CI Repository. Further information about the process is documented in the README.md.

The Swift community-hosted CI allows un-supported platforms to be moved over to a supported platform on a case by case basis. Depending on the number of nodes provided, @swift-ci pull request testing can be integrated with the community-hosted CI as well.