VM Scripts

This repository contains a sample setup to illustrate how to build R unattended using macosvm.

Initial setup

In the following we assume that your working directory is inside the checkout of this repository and that you have downloaded macosvm (see macosvm releases) and put it on your PATH.

First, you have to create a VM with your base macOS and Command Line Tools. Most of this is described in the README of macosvm, but here is the short version:

1. Download the restore image for the macOS version you want to use. Note that is must be same or lower than your host macOS version. For example, for macOS 14 (Sonoma) you can use

   curl -LO https://updates.cdn-apple.com/2024SummerFCS/fullrestores/062-52859/932E0A8F-6644-4759-82DA-F8FA8DEA806A/UniversalMac_14.6.1_23G93_Restore.ipsw
   

2. Restore the macOS into a new disk image:

   macosvm --disk disk.img,size=64g --aux aux.img \
     --restore UniversalMac_14.6.1_23G93_Restore.ipsw vm.json
   

   (You can prepend e.g. -c6 -r8g if you want to increase the number of cores to 6 and use 8Gb of RAM). The important part here is that the settings will be stored in the vm.json file.

3. Boot the new VM with GUI:

   macosvm -g vm.json
   

   Follow the Apple Setup Assistant and make sure you use the following (unless you want to change the scripts):

   1. create user with login rbuild
   2. once the setup is complete enable ssh ("System Settings" -> "Remote Login"). It is typically wise to also enable "Screen Sharing" (makes administration easier, but the scripts don't care).
   3. install developer command line tools by opening the Terminal and typing:

      xcode-select --install
      

      and follow the on-screen instructions. You can check that they work e.g. by typing make.
   4. You can enable passwordless sudo for admins by typing the following in Terminal:

      sudo bash -c "echo '%admin ALL = (ALL) NOPASSWD: ALL' > /etc/sudoers.d/10admins"
      

      You will need this if you want the scripts to be fully autonomous.
   5. Add your ssh public key from your host user account to ~/.ssh/authorized_keys on the VM so you can ssh into the VM without password.

Once you're done with the setup, you can shutdown the VM (either from the top-left menu or with sudo shutdown -h now in Terminal).

Testing

At this point you should have a nice, clean macOS VM image that can be used. You can test it by running:

macosvm --ephemeral --script ./launch.sh vm.json

(or ./run.sh) You should see it booting up something like this:

2025-11-05 19:46:44.331 macosvm[66388:4542531]  . cloning disk.img to ephemeral disk.img-clone-66388
2025-11-05 19:46:44.332 macosvm[66388:4542531]  . cloning aux.img to ephemeral aux.img-clone-66388
2025-11-05 19:46:44.374 macosvm[66388:4542531] Creating instance ...
[...]
2025-11-05 19:46:55.285 macosvm[66409:4542793] start completed err=nil
Waiting for IP address of 8a:2b:c2:9a:e2:ed.......

ssh -o StrictHostKeyChecking=accept-new [email protected]

The last part is the launch.sh script telling you how to ssh into the newly created instance. By adding --ephemeral we make sure that this is a throw-away instrance, i.e. all changes will be discarded once the VM is shut down. Run the displayed ssh command on your host to login into the VM. If you setup things correctly, it should give you a shell prompt inside the VM. If it asks for a password, then you didn't create ~/.ssh/authorized_keys properly in the VM (to fix it, run macosvm without --ephemeral or ./run.sh -p). You can then shut down the VM with sudo shutdown -h now.

Note that you can always shutdown the VM ungracefully by pressing <Ctrl><C> in the Terminal window on the host that launched macosvm.

Build environment

TLDR; If you just want to run the build, skip this and read the next section.

The builds use one addtional feature of macosvm which is the ability to mount directories on the host as volumes inside the VM. The script uses --vol "$(pwd)/shared",automount to mount the shared directory as /Volumes/My Shared Files volume inside the VM. The setup.sh script in the shared directory then sets up the system environment to include all necessary pieces such as XQuartz, GNU Fortran, dependent libraries etc. Since the volume is mounted, it allows even ephemeral VMs to pick up content and leave results in the mounted volume. The setup.sh script caches downloaded content to speed up installation in the next run.

If you plan to use the same tools more often, you can drop the --ephemeral flag, then just run setup.sh inside the VM with the volume mounted and shut down the VM. Subsequent runs will then already have the tools in the disk.img.

Finally, note that you can keep both a clean image and an image with tools around by first creating a copy with

cp -c disk.img disk-clean.img

and then running the VM without --ephemeral to create a version of disk.img with the tools. The -c flags tells cp to make a "clone" which is a "virtual" copy that does not use any addtional space (at least on APFS), but won't change even if the original file changes. You can roll back to the clean state if desired by using cp -c disk-clean.img disk.img.

Running the build

If all went well then you can run the build simply with

./run-build.sh

It mounts the shared directory as a volume in the VM, starts an ephemeral VM (i.e., it clones disk.img for the duration of the VM execution and removes it afterwards), and when it is up starts launch-build.sh which waits until the VM is visible on the network and the uses ssh to log into it to start the run-arm64.sh to call build.sh. Note that passworless ssh from the host must work for this (see 3.v. above).

The actual script that will be run on the VM is the one in shared/build.sh so you can edit it as needed. It calls the shared/setup.sh script to setup the enviroment first, then checks if the R sources are in shared/R (if not, it uses svn to check out R-devel) and builds those with make dist in the R-build-<ts> directory, copuing the resulting tar ball into shared on the host.