Coming soon: Gen2 macOS Resources!

We are excited to announce that we released a new generation of macOS on December 15th!! These new resources can speed up your builds by up to 50%! Gen2 macOS resources is available to all customers on a Performance, Custom, or Scale plan. We are only offering a medium size option with these resources at this time.

As part of this release, we are also introducing new resource class naming, in an effort to provide more clarity on the executor being used. Note: this change will not impact our existing medium and large macOS resource classes.

If you want to start running your macOS jobs on the next generation resources, just update your config to the macos.x86.medium.gen2 resource class!

Example config

# .circleci/config.yml
version: 2.1
jobs: # a basic unit of work in a run
  build-and-test: # your job name
      xcode: 12.5.1 # indicate your selected version of Xcode
    resource_class: macos.x86.medium.gen2 # new generation resources
    steps: # a series of commands to run
      - checkout  # pull down code from your VCS
      - run: bundle install
      - run:
          name: Fastlane
          command: bundle exec fastlane $FASTLANE_LANE
      - store_artifacts:
          path: output
      - store_test_results:
          path: output/scan
      - build-and-test

Specs and Pricing

Resource Class Name: macos.x86.medium.gen2
vCPU: 4 @ 3.2GHz
Memory: 8GB
Price: 75 credits/minute


Can’t wait to try this out!

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Quick update: We’re investigating an issue that impacts our Gen2 macOS resources and, unfortunately, need to delay this launch. I’ll post another update once I have a new release date, but expect it will be next week, if not sooner. Thank you for your patience and understanding!

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Thanks for the heads up, @alexazl. We’re looking forward to trying it out.

If we go ahead and set resource_class: macos.x86.medium.gen2 now, will jobs fall back to medium until macos.x86.medium.gen2 becomes available, or will they just fail?

@brow it looks like CircleCI falls back to using the medium resource class based on what I recently tested after setting the config’s resource class to macos.x86.medium.gen2.


@brow is correct! You will be defaulted to the medium resource class until the new class becomes available.

You may see a message about upgrading to a Performance plan when this occurs, but you can disregard that. We’re also looking into updating the message to avoid confusion. Thanks, again, for your patience!

We have identified the root cause of the issue and are now working on a solution. I don’t have a new release date, yet, but should be able to provide one by the end of the week!

We have also fixed our message to reduce confusion for those who try to use this new resource class before they’re available. Additionally, customers who were part of the closed preview should continue using the old resource class tag until the new launch date.

Great news! We have identified a solution and are working on implementing it. The new launch date for the Gen2 resources will be next Wednesday, December 15th!!


Has this happened?

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Gen2 resources for Mac are officially available!!

If you were part of the preview, please be sure to update your config to macos.x86.medium.gen2 before the end of the month. The old resource class name will be deprecated on December 31, 2021.

I hope everyone enjoys the rest of the holiday season and 2021! :tada:

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A 40% reduction in build time for free! Thanks for your work on this, @alexazl, and happy holidays.



Just tested this and it looks like it does perform a lot faster! However, we have a highly parallelized workflow and we are seeing most workers take three minutes to get allocated a VM. Is this expected and will it improve in the future? It takes away from a lot of the speed gain :frowning_face:

I’m also seeing very slow environment spin-up times - as slow as 5 minutes today. This really isn’t acceptable when we’re already trying everything we can to keep our build times as quick as possible. A 5 minute spin-up time can multiply quickly when you have 5 or 6 jobs in your workflow.

I’m seeing this on both the stable Xcode 13.2 images and the new MacOS 12/Xcode 13.3 beta images.

Hi Luke,

Although the nature of using Mac environments means that spin-up times can vary 5 minute spin-up times are unexpected. Did you experience this before today? Would you mind if I messaged you privately and you can send me a link to the build where you were experiencing the slow spin up times and we can investigate it on our end?


Please feel free to message me privately - I haven’t seen spin up times that slow before today but I have seen spin-up times that take 2-3 minutes regularly before today.

Would it be possible to get the jsonschema at updated so we don’t get warnings when using the new resource class identifier?


This is a 3rd party project, not maintained by us, so I am not sure how long it will take for them to merge it in