Migration Guide

Cirrus CI is shutting down.
Here’s how to move.

On April 7, 2026, Cirrus Labs announced they're joining OpenAI. Cirrus CI will stop running jobs on June 1, 2026.

Cirrus was genuinely great. They were the first to offer affordable macOS CI on Apple Silicon through Tart, with per-second billing and generous open source tiers. Projects like PostgreSQL, Bitcoin Core, and Podman relied on them.

But your workflows will break in 8 weeks. Here's how to move.

Why Zag

Cheapest macOS compute available.

We offer Apple Silicon M4 runners at cost. Dramatically cheaper than GitHub Actions ($0.08–0.16/min), WarpBuild (~$0.03–0.05/min), and Blacksmith (~$0.04–0.08/min).

Zero-migration support for .cirrus.yml.

We natively parse and run your existing Cirrus CI config. Install our GitHub App and your macOS tasks keep working with zero changes.

One-line migration for GitHub Actions users.

If you're already on GitHub Actions alongside Cirrus CI, just change runs-on.

AI review agents included.

Unlike every other runner provider, Zag includes AI review agents that can actually build your project, launch it in the iOS Simulator, and catch crashes, layout issues, and regressions on every PR. Toggle it on with zero configuration, or write custom agents in TypeScript or Swift.

Apple Silicon M4 hardware.

Fast boot times. Ephemeral VMs. Real metal, not emulation.

Migration guide

Path 1

You have a .cirrus.yml

The easiest path

This is the path nobody else offers. Zag natively supports Cirrus CI configuration files. You don’t need to rewrite anything.

1. Install the Zag GitHub App.

2. Your existing .cirrus.yml macOS tasks run on Zag’s infrastructure.

3. That’s it.

.cirrus.yml

# Your existing .cirrus.yml - no changes needed
macos_instance:
  image: ghcr.io/cirruslabs/macos-runner:sonoma

build_task:
  install_script:
    - brew install swiftlint
  build_script:
    - xcodebuild build -scheme MyApp \
        -destination 'platform=iOS Simulator,name=iPhone 16'
  test_script:
    - xcodebuild test -scheme MyApp \
        -destination 'platform=iOS Simulator,name=iPhone 16'

Zag natively supports core Cirrus CI primitives: macos_instance, script, cache, env, matrix, and depends_on.

Path 2

You’re already on GitHub Actions

Just swap your runner label:

.github/workflows/ci.yml

# Before
runs-on: macos-latest

# After
runs-on: zag-macos-m4

One line. Done. Your existing workflow steps, caching, and secrets all work the same.

Path 3

Turn on AI review agents

Optional, after migration

Once you're on Zag, you can optionally enable AI review agents. Zero configuration required.

Zag agents build your project on every PR, boot it on iOS and iPadOS simulators, navigate your key flows, and catch crashes, layout regressions, and visual issues. Screenshots and stack traces get posted as PR comments automatically.

When you're ready to go deeper, write custom agents in TypeScript or Swift. App Store compliance checks, security pen tests, accessibility audits, performance regression detection.

Comparison

Zag

GitHub Actions

WarpBuild

Blacksmith

Price/min

~$0.003 (at cost)

$0.08–0.16

~$0.03–0.05

~$0.04–0.08

Hardware

Apple Silicon M4

M1 / Intel

M4 Pro

.cirrus.yml

✓ Native

✗

AI agents

✓ Built-in

✗

Setup

Install GitHub App

Already there

1 line change

Get started in 5 minutes.

Book a demo

Running an open source project on Cirrus CI? Email us at hello@zag.dev and we’ll migrate you for free.

Questions? Talk to us on Discord or email founders@zag.dev