These questions come up regularly, so here are the answers.
The macOS software license allows running (some versions of) macOS in a virtual machine only on Apple hardware. The Apple Security Bounty terms and conditions make an exception to that (and essentially anything in the macOS software license) under some specific circumstances.
Therefore, yes, there is a legal use for Docker-OSX. If your use doesn't fall under the license or the security bounty terms, then you are/will be violating the macOS software license. Note that this is not provided as legal advice, and you should consult with your own counsel for legal guidance.
You may also be interested in this deeper dive into the subject.
Docker-OSX is an approach to setting up and launching a macOS virtual machine (VM) under docker. The Dockerfile is essentially a docker image building script that:
- validates a few things about the environment
- installs VM software (qemu) and creates a virtual disk within the docker container
- generates a serial number and firmware to make the VM look (enough) like Mac hardware
- downloads a macOS installer disk image
- generates a shell script to start the VM
The default configuration is intended to create an ephemeral but repeatably bootable macOS that can be probed for security research.
Docker provides a straightforward way to package a flexible turnkey solution to setting up a macOS VM. It is not the only way to do so, nor is it necessarily the best approach to setting up a long-lived, persistent macOS VM. You may prefer to study the Dockerfile and/or OSX-KVM to prepare a VM to run under proxmox or libvirt.
Yes. Make sure you make serial numbers persist across reboots after generating a unique serial number for yourself; don't use the default serial number. There is, of course, no guarantee that Apple won't block/disable your account, or inflict other consequences. See also the legal considerations.
Yes. You will probably find Xcode's UI frustratingly slow, but yes. Compiling apps (e.g. React Native) from the command line is likely to be less frustrating. There is, of course, no guarantee that Apple won't block/disable your account, remove you from the Apple Developer program, or inflict other consequences. See also the legal considerations.
Yes, at least if your host OS is Linux. See instructions. It may or may not be possible if your host OS is Windows.
Maybe, but there are several reasons not to:
- There are legal considerations.
- Nested virtualization is generally unavailable on cloud-hosted CI/CD and therefore Docker-OSX doesn't run.
- You are almost always better off using your own macOS runners (on virtual or actual Mac hardware) rather than trying to make the square peg of Docker-OSX fit the round hole of macOS-specific CI/CD.
You absolutely can install runners on the macOS VM itself (which does not get around the legal considerations mentioned above), but Docker-OSX may not be the best approach.
Yes, but your Wayland server must support X11 connections (or you can use VNC instead).
Yes, as long as you have a new enough version of Windows 11 and have WSL2 set up. See this section of the README for details. No, it will not work under Windows 10. Not even if you have WSL2 set up.
If you have a Mac with Apple Silicon you are better served by UTM.
If you have an Intel Mac you can install and run docker (either Docker Desktop or colima). In either case, docker will be running under a Linux VM, which complicates things. You are likely to encounter one or more of the common errors below. Consider using qemu directly with HVF acceleration (e.g. with libvirt) instead.
Cloud providers typically run their various services within virtual machines running on top of their actual hardware. These VMs typically are not set up to provide nested virtualization, which means KVM is unavailable so Docker-OSX will not work. This is especially and specifically the case on CI/CD runners such as GitHub Actions, Azure DevOps Pipelines, CircleCI, GitLab CI/CD, etc. (however, see running CI/CD). Some cloud providers offer services that do allow virtualization, such as Amazon's EC2 Bare Metal Instances, but often at a significant premium.
In short, probably not.
If you get an error like docker: command not found then you don't have docker installed and none of this works. Try Docker Desktop on Windows or your distribution's normal package manager on Linux.
If you get an error like docker: Got permission denied while trying to connect to the Docker daemon or docker: unknown server OS: . the mostly likely explanation is that your user isn't in the docker Unix group. You'll need to add yourself to the docker group, log out, and log back in.
If you get an error like Cannot connect to the Docker daemon at unix://var/run/docker.sock. Is the docker daemon running? then dockerd isn't running. On most Linux distributions you should be able to start it with sudo systemctl enable docker --now.
This is an X11 error and means that the arguments to qemu are telling it to connect to an X11 display that it either can't connect to at all or doesn't have permission to connect to. In the latter case, this can usually be fixed by running xhost + on the host running the X11 server.
In many cases, however, it is preferable to tell qemu to listen for a VNC connection instead of trying to connect to X11; see this section of the README for instructions.
If you get an error like error gathering device information while adding custom device "/dev/kvm": no such file or directory that means KVM is not available/working on the Linux kernel on which you are running docker. This could be because you are attempting to run somewhere that doesn't support nested virtualization (see above), or because your BIOS does not have virtualization extensions turned on, or because your CPU is too old to support virtualization extensions, or your Linux kernel does not have KVM support loaded/enabled. Fixing KVM issues is well beyond the scope of this document, but you can start here.
You might get an error like this:
(qemu) ALSA lib confmisc.c:767:(parse_card) cannot find card '0'
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1246:(snd_func_refer) error evaluating name
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5233:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM default
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib confmisc.c:767:(parse_card) cannot find card '0'
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1246:(snd_func_refer) error evaluating name
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5233:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM default
alsa: Could not initialize DAC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `dac'
ALSA lib confmisc.c:767:(parse_card) cannot find card '0'
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1246:(snd_func_refer) error evaluating name
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5233:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM default
alsa: Could not initialize ADC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
ALSA lib confmisc.c:767:(parse_card) cannot find card '0'
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1246:(snd_func_refer) error evaluating name
ALSA lib conf.c:4745:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:5233:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2660:(snd_pcm_open_noupdate) Unknown PCM default
alsa: Could not initialize ADC
alsa: Failed to open `default':
alsa: Reason: No such file or directory
audio: Failed to create voice `adc'
Docker-OSX defaults to telling qemu to use ALSA for audio output. Your host system may be using PulseAudio instead (see PulseAudio), but you may not need audio output at all. You can pass -e AUDIO_DRIVER="id=none,driver=none" to disable audio output.
If you have launched the installer but don't see a disk to install macOS on, it probably means you skipped the step where you run Disk Utility to format the virtual disk. See the README.
This is not unique to virtual hardware. The macOS installation process gives apparently random and dependably incorrect time estimates, and can often appear to have completely frozen. Just be patient. It could take hours, maybe even more than a day.
If you wind up in the installer again after you've installed macOS it means you booted from the installer disk instead of the disk you installed macOS on. Reboot and make sure you choose the correct disk to boot.
Congratulations, you got a macOS VM up and running! Now what?
The macOS UI expects and relies on GPU acceleration, and there is (currently) no way to provide GPU acceleration in the virtual hardware. See osx-optimizer for macOS configuration to speed things up.
With the container stopped, sudo find /var/lib/docker -size +10G -name mac_hdd_ng.img to find the disk image then copy it where you want it.
Is your host machine's disk, specifically /var (because of /var/lib/docker), getting full? Fix it.
The RAM, SMP, and CORES options are all docker environment variables, which means it uses whatever you provide any time you start a container.