About GitHub-hosted runners

Overview of GitHub-hosted runners

Runners are the machines that execute jobs in a GitHub Actions workflow. For example, a runner can clone your repository locally, install testing software, and then run commands that evaluate your code.

GitHub provides runners that you can use to run your jobs, or you can host your own runners. Each GitHub-hosted runner is a new virtual machine (VM) hosted by GitHub with the runner application and other tools preinstalled, and is available with Ubuntu Linux, Windows, or macOS operating systems. When you use a GitHub-hosted runner, machine maintenance and upgrades are taken care of for you.

Using a GitHub-hosted runner

To use a GitHub-hosted runner, create a job and use runs-on to specify the type of runner that will process the job, such as ubuntu-latest, windows-latest, or macos-latest. For the full list of runner types, see "Supported runners and hardware resources."

When the job begins, GitHub automatically provisions a new VM for that job. All steps in the job execute on the VM, allowing the steps in that job to share information using the runner's filesystem. You can run workflows directly on the VM or in a Docker container. When the job has finished, the VM is automatically decommissioned.

The following diagram demonstrates how two jobs in a workflow are executed on two different GitHub-hosted runners.

The following example workflow has two jobs, named Run-npm-on-Ubuntu and Run-PSScriptAnalyzer-on-Windows. When this workflow is triggered, GitHub provisions a new virtual machine for each job.

• The job named Run-npm-on-Ubuntu is executed on a Linux VM, because the job's runs-on: specifies ubuntu-latest.
• The job named Run-PSScriptAnalyzer-on-Windows is executed on a Windows VM, because the job's runs-on: specifies windows-latest.

name: Run commands on different operating systems
on:
  push:
    branches: [ main ]
  pull_request:
    branches: [ main ]

jobs:
  Run-npm-on-Ubuntu:
    name: Run npm on Ubuntu
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
        with:
          node-version: '14'
      - run: npm help

  Run-PSScriptAnalyzer-on-Windows:
    name: Run PSScriptAnalyzer on Windows
    runs-on: windows-latest
    steps:
      - uses: actions/checkout@v3
      - name: Install PSScriptAnalyzer module
        shell: pwsh
        run: |
          Set-PSRepository PSGallery -InstallationPolicy Trusted
          Install-Module PSScriptAnalyzer -ErrorAction Stop
      - name: Get list of rules
        shell: pwsh
        run: |
          Get-ScriptAnalyzerRule

While the job runs, the logs and output can be viewed in the GitHub UI:

La aplicación ejecutora de GitHub Actions es de código abierto. Puedes contribuir y emitir informes de problemas en el repositorio runner.

Supported runners and hardware resources

Hardware specification for Windows and Linux virtual machines:

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

Hardware specification for macOS virtual machines:

• 3-core CPU
• 14 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. The update process takes several days, and the list of preinstalled software on the main branch is updated after the whole deployment ends.

Preinstalled software

Workflow logs include a link to the preinstalled tools on the exact runner. To find this information in the workflow log, expand the Set up job section. Under that section, expand the Virtual Environment section. The link following Included Software will describe the preinstalled tools on the runner that ran the workflow. For more information, see "Viewing workflow run history."

For the overall list of included tools for each runner operating system, see the links below:

• Ubuntu 20.04 LTS
• Ubuntu 18.04 LTS
• Windows Server 2022
• Windows Server 2019
• macOS 12
• macOS 11
• 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.

Using preinstalled software

We recommend using actions to interact with the software installed on runners. This approach has several benefits:

• Usually, actions provide more flexible functionality like versions selection, ability to pass arguments, and parameters
• It ensures the tool versions used in your workflow will remain the same regardless of software updates

If there is a tool that you'd like to request, please open an issue at actions/virtual-environments. This repository also contains announcements about all major software updates on runners.

Installing additional software

You can install additional software on GitHub-hosted runners. For more information, see "Customizing GitHub-hosted runners".

Cloud hosts used by 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 resources, see "Dv2 and DSv2-series" in the Microsoft Azure documentation.

GitHub hosts macOS runners in GitHub's own macOS Cloud.

Workflow continuity

Si los servicios de las GitHub Actions se encuentran temporalmente no disponibles, entonces se descartará una ejecución de flujo de trabajo si no se puso en cola en los primeros 30 minutos después de activarse. Por ejemplo, si un flujo de trabajo se activa y los servicios de las GitHub Actions no están disponibles por 31 minutos o más, entonces la ejecución de flujo de trabajo no se procesará.

In addition, if the workflow run has been successfully queued, but has not been processed by a GitHub-hosted runner within 45 minutes, then the queued workflow run is discarded.

Administrative privileges

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.

IP addresses

To get a list of IP address ranges that GitHub Actions uses for GitHub-hosted runners, you can use the GitHub REST API. For more information, see the actions key in the response of the "Get GitHub meta information" endpoint.

Windows and Ubuntu runners are hosted in Azure and subsequently have the same IP address ranges as the Azure datacenters. macOS runners are hosted in GitHub's own macOS cloud.

Since there are so many IP address ranges for GitHub-hosted runners, we do not recommend that you use these as allow-lists for your internal resources.

The list of GitHub Actions IP addresses returned by the API is updated once a week.

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 - Nota:GitHub Actions debe ejecutarse por el usuario predeterminado (root) de Docker. Asegúrate de que tu Dockerfile no configure la instrucción de USER, de lo contrario, no podrás acceder a GITHUB_WORKSPACE.
• /github/workflow

Further reading

• "Managing billing for GitHub Actions"
• You can use a matrix strategy to run your jobs on multiple images. For more information, see "Using a matrix for your jobs."