# Runner Images (https://tenki.cloud/docs/runners/runner-images)

> For the complete documentation index, see [llms.txt](https://tenki.cloud/llms.txt)

What's preinstalled on Tenki Linux and macOS runner images, how we build them with Packer and VMs, and how to request custom images.



This page describes what's on a Tenki runner image out of the box, how we build them, and how custom images work.

Linux x64 default image [#linux-x64-default-image]

Tenki Linux x64 runners use the **official GitHub Actions runner images** maintained at [`actions/runner-images`](https://github.com/actions/runner-images). The default image is **Ubuntu 24.04**.

Practical consequence: anything that runs on GitHub-hosted `ubuntu-latest` runs on Tenki Linux runners with no changes. The toolchains (Node, Python, Ruby, Java, Go, Rust, Docker, gcloud, AWS CLI, fastlane, Android SDK + NDK, etc.) are identical to GitHub's, on the same version cadence.

macOS default image [#macos-default-image]

Tenki macOS Runners use a curated image based on **macOS 15 Sequoia** with the toolchain we recommend for iOS, macOS app, and cross-platform builds.

For Xcode version pinning, parallel Xcode availability, or fully custom macOS images, see [macOS Xcode & Custom Images](/docs/runners/macos-xcode-and-images).

How we build images [#how-we-build-images]

Both Linux and macOS images are built with **Packer** and run as **VM-based** images on our fabric. Internal customers (and now external) benefit from:

* Reproducible image builds
* Fast cold boot ([\~15 seconds](/docs/runners/limits-and-concurrency#cold-start))
* Predictable image refresh cadence

Custom images [#custom-images]

We support fully custom images for both Linux x64 and macOS. The typical use cases:

* Internal SDKs, proprietary tooling, or licensed dependencies that can't live in a public registry
* A specific Xcode / simulator matrix that needs to be locked in
* Pre-warmed caches for very large monorepos

Custom images are scoped during onboarding and tied to committed capacity. Contact [hello@tenki.cloud](mailto:hello@tenki.cloud) to start the conversation.

> **What's on the image today?:** If you want the exact tool/version list before migrating, email hello@tenki.cloud, we'll send the current manifest.