Creating new macOS VMs to build MullvadVPN iOS in a CI environment

This guide assumes you are running on macOS.

Prerequisites

In order to create VMs on the fly, we decided to use tart and packer.

The various scripts that run in the VM are written in bash with the help of shellcheck.

VM requirements

You will need at least 60GB of available space on your VM host
You will need at least 8GB of available RAM on your VM host
You will need at least 4 CPU cores available on your VM host

How to install Tart

brew install cirruslabs/cli/tart

How to install Packer

brew tap hashicorp/tap
brew install hashicorp/tap/packer

How to install shellcheck

brew install shellcheck

[!IMPORTANT]

Prerequisite setup before running packer

Get a copy of the Xcode version you want to install on the VM in a xip format

Copy that file into the folder named vm_shared_folder

Open the file named variables.pkrvars.hcl

Edit the variables named xcode_version and xcode_xip_name

Here is an example of what to expect

bash

% ls vm_shared_folder
Xcode_15.0.1.xip
% head -2 variables.pkrvars.hcl
xcode_version = "15.1"
xcode_xip_name = "Xcode_15.1.xip"

Sanity checks before running packer

It is a good idea to keep logs, the logs folder is provided to that effect. Enable packer logs by setting the following environment variables (assuming your are running with zsh)

export PACKER_LOG=1
export PACKER_LOG_PATH="logs/packer_logs.txt"

[!NOTE] The logs will be overwritten with each packer command you issue.

You can then check that the templates are valid before running packer

packer inspect -var-file="variables.pkrvars.hcl" install-build-dependencies.pkr.hcl
packer validate -var-file="variables.pkrvars.hcl" install-build-dependencies.pkr.hcl

You can make sure you are not missing any dependencies with the init command

packer init install-vanilla-ventura.pkr.hcl

Create the VM image via Packer

Once your setup is ready, you just need one command to create a VM. And one more to install Xcode on it.

packer build -var-file="variables.pkrvars.hcl" install-vanilla-ventura.pkr.hcl

Install Xcode on the VM image via Packer

packer build -var-file="variables.pkrvars.hcl" install-build-dependencies.pkr.hcl

[!IMPORTANT] At the time of writing this, tart does not support VM snapshotting. This means that any action taken by packer will be permanent on the VM.

Make sure to properly clean up the VM before running packer commands again if something went wrong. You can look at the cleanup.sh script in the scripts folder to see what type of cleanup is ran in case things go wrong.