This repository contains the source used to create the virtual environments for GitHub Actions hosted runners, as well as the VM images of Microsoft-hosted agents used for Azure Pipelines. To build a VM machine from this repo's source, see the instructions.

How to get in touch with us:

• To file a bug report, or request tools to be added/updated, please open an issue using the appropriate template
• If you want to share your thoughts about image configuration, installed software, or bring some idea, please, create a new topic in a discussions section for a corresponding category. Before making a new discussion please make sure no similar topics were created earlier.

For general questions about using the virtual environments or writing your Actions workflow, please open requests in the GitHub Actions Community Forum.

Environment	YAML Label	Included Software	Latest Release & Rollout Progress
Ubuntu 20.04	ubuntu-latest or ubuntu-20.04	ubuntu-20.04
Ubuntu 18.04	ubuntu-18.04	ubuntu-18.04
macOS 11	macos-11	macOS-11
macOS 10.15	macos-latest or macos-10.15	macOS-10.15
Windows Server 2019	windows-latest or windows-2019	windows-2019
Windows Server 2016	windows-2016	windows-2016

Ubuntu 16.04 has been deprecated and will be removed on September 20, 2021.
Existing workflows using `Ubuntu 16.04` should migrate to `Ubuntu 20.04` or `Ubuntu 18.04`

The macOS 11 virtual environment is currently in preview and is automatically available to the existing Enterprise plan customers who used macOS hosted runners at least once between May, 1 - June, 1. New Enterprise plan customers, or customers on other plans, should fill the form to request access to macOS 11 virtual environment. Please view our Big Sur guide for more details.
The macos-latest YAML workflow label still uses the macOS 10.15 virtual environment.

What images are available for GitHub Actions and Azure DevOps? The availability of images for GitHub Actions and Azure DevOps is different. See documentation for more details:

• GitHub Actions
• Azure DevOps

What image version is used in my build? Usually, image deployment takes 3-4 days, and documentation in the main branch is only updated when deployment is finished. To find out which image version and what software versions are used in a specific build, see Set up job (GitHub Actions) or Initialize job (Azure DevOps) step log.

Looking for other Linux distributions? We do not plan to offer other Linux distributions. We recommend using Docker if you'd like to build using other distributions with the hosted virtual environments. Alternatively, you can leverage self-hosted runners and fully customize your environment to your needs.

How to contribute to macOS source? macOS source lives in this repository and available for everyone. However, MacOS image-generation CI doesn't support external contributions yet so we are not able to accept pull-requests for now. We are in the process of preparing MacOS CI to accept contributions. Until then, we appreciate your patience and ask you continue to make tool requests by filing issues.

Cadence

We typically deploy weekly updates to the software on the virtual environments. For some tools, we always install the latest at the time of the deployment; for others, we pin the tool to specific version(s).

Following Along / Change Notifications

• High Impact Changes (ex. breaking changes, new or deprecated environments) will be posted to the GitHub Changelog on our blog and on twitter.
• Low Impact Changes will be pinned in this repository and marked with the Announcement label.
• Regular Weekly Rhythm can be followed by watching Releases. Pre-release is created when deployment is started. As soon as deployment is finished, it is converted to release. You can also track upcoming changes using the awaiting-deployment label.

To learn more about tools and images support policy, see the guidelines.