Specifications for GitHub-hosted runners

About GitHub-hosted runners

A GitHub-hosted runner is a virtual machine hosted by GitHub with the GitHub Actions runner application installed. GitHub offers runners with Linux, Windows, and macOS operating systems.

When you use a GitHub-hosted runner, machine maintenance and upgrades are taken care of for you. You can run workflows directly on the virtual machine or in a Docker container.

You can specify the runner type for each job in a workflow. Each job in a workflow executes in a fresh instance of the virtual machine. All steps in the job execute in the same instance of the virtual machine, allowing the actions in that job to share information using the filesystem.

GitHub Actions 运行器应用程序是开源的。 您可以参与 runner 仓库并在其中提交议题。

Cloud hosts for GitHub-hosted runners

GitHub hosts Linux and Windows runners on Standard_DS2_v2 virtual machines in Microsoft Azure with the GitHub Actions runner application installed. The GitHub-hosted runner application is a fork of the Azure Pipelines Agent. Inbound ICMP packets are blocked for all Azure virtual machines, so ping or traceroute commands might not work. For more information about the Standard_DS2_v2 machine resources, see "Dv2 and DSv2-series" in the Microsoft Azure documentation.

GitHub uses MacStadium to host the macOS runners.

Administrative privileges of GitHub-hosted runners

The Linux and macOS virtual machines both run using passwordless sudo. When you need to execute commands or install tools that require more privileges than the current user, you can use sudo without needing to provide a password. For more information, see the "Sudo Manual."

Windows virtual machines are configured to run as administrators with User Account Control (UAC) disabled. For more information, see "How User Account Control works" in the Windows documentation.

Supported runners and hardware resources

Each virtual machine has the same hardware resources available.

• 2-core CPU
• 7 GB of RAM memory
• 14 GB of SSD disk space

Workflow logs list the runner used to run a job. For more information, see "Viewing workflow run history."

Supported software

The software tools included in GitHub-hosted runners are updated weekly. For the latest list of included tools for each runner operating system, see the links below:

• Ubuntu 20.04 LTS
• Ubuntu 18.04 LTS
• Ubuntu 16.04 LTS
• Windows Server 2019
• Windows Server 2016
• MacOS 10.15

GitHub-hosted runners include the operating system's default built-in tools, in addition to the packages listed in the above references. For example, Ubuntu and macOS runners include grep, find, and which, among other default tools.

Workflow logs include a link to the preinstalled tools on the runner. For more information, see "Viewing workflow run history."

If there is a tool that you'd like to request, please open an issue at actions/virtual-environments.

IP addresses

Windows and Ubuntu runners are hosted in Azure and have the same IP address ranges as Azure Data centers. Currently, all Windows and Ubuntu GitHub-hosted runners are in the following Azure regions:

• East US (eastus)
• East US 2 (eastus2)
• West US 2 (westus2)
• Central US (centralus)
• South Central US (southcentralus)

Microsoft updates the Azure IP address ranges weekly in a JSON file that you can download from the Azure IP Ranges and Service Tags - Public Cloud website. You can use this range of IP addresses if you require an allow-list to prevent unauthorized access to your internal resources.

The JSON file contains an array called values. Inside that array, you can find the supported IP addresses in an object with a name and id of the Azure region, for example "AzureCloud.eastus2".

You can find the supported IP address ranges in the "addressPrefixes" object. This is a condensed example of the JSON file.

{
  "changeNumber": 84,
  "cloud": "Public",
  "values": [
    {
      "name": "AzureCloud.eastus2",
      "id": "AzureCloud.eastus2",
      "properties": {
        "changeNumber": 33,
        "region": "eastus2",
        "platform": "Azure",
        "systemService": "",
        "addressPrefixes": [
          "13.68.0.0/17",
          "13.77.64.0/18",
          "13.104.147.0/25",
          ...
        ]
      }
    }
  ]
}

File systems

GitHub executes actions and shell commands in specific directories on the virtual machine. The file paths on virtual machines are not static. Use the environment variables GitHub provides to construct file paths for the home, workspace, and workflow directories.

For a list of the environment variables GitHub creates for each workflow, see "Using environment variables."

Docker container filesystem

Actions that run in Docker containers have static directories under the /github path. However, we strongly recommend using the default environment variables to construct file paths in Docker containers.

GitHub reserves the /github path prefix and creates three directories for actions.

• /github/home
• /github/workspace - 注：GitHub Actions 必须由默认 Docker 用户 (root) 运行。 确保您的 Dockerfile 未设置 USER 指令，否则您将无法访问 GITHUB_WORKSPACE。
• /github/workflow

Further reading

• "Managing billing for GitHub Actions"