Replacing Docker Desktop for Mac with Colima

December 21, 2021

Docker Desktop for Mac is probably the most commonly used solution to run Docker on macOS. It runs the daemon in a VM, handles port-forwarding, shared folders and sets up the Docker CLI. It's a quick and easy way to get Docker running on macOS.

Although technically it works fine, the following reasons made me look for a replacement:

Closed-source
Pop-ups asking me how likely I am to recommend Docker Desktop to a co-worker
Weekly tips and anonymous reporting are enabled by default
It makes a request to desktop.docker.com every time the settings are opened, even with anonymous reporting turned off

While there is the option to run something like Multipass or VirtualBox with a custom provisioning script for Docker and then configure shared folders, I was looking for a drop-in replacement with minimal or no configuration.

Colima fits the criteria well. It's based on Lima which creates a QEMU VM with HVF accelerator and handles the port-forwarding and folder sharing. Lima comes with containerd and nerdctl installed, but for a drop-in replacement the Docker container runtime is required which is what Colima is for.

Colima provisions the Docker container runtime in a Lima VM, configures the docker CLI on macOS and handles port-forwarding and volume mounts. This makes Docker easily usable on macOS without any configuration, similar to Docker Desktop.

Installation and Usage

Installation is easy and can be done through Homebrew:

brew install colima

To start the VM we run:

colima start

It will start the docker daemon in the VM and configure the docker CLI on the host. The usage in macOS is no different from Docker Desktop, and all docker commands should work as before.

Performance

Since both solutions are based on the macOS HVF I don't think there is much difference in terms of CPU and memory performance. However, shared folder performance has always been a bottleneck for Docker on macOS.

I think it's worth to test the differences in performance since Docker Desktop uses gRPC FUSE while Colima/Lima uses sshfs to share folders.

I've used fio to run a quick benchmark in Docker desktop for mac (v4.3.1) and colima (v0.2.2) that performs random 4K writes on a shared volume:

fio --name=random-write --ioengine=libaio --rw=randwrite --direct=1 --bs=4k --size=4g --numjobs=1 --iodepth=16 --runtime=60 --time_based --end_fsync=1 --filename=/app/testfile

The results:

# Docker Desktop for Mac
IOPS: 1545
Bandwidth: 6.3MB/s

# Colima
IOPS: 2786
Bandwidth: 11.4MB/s

We can see that Colima is around 80% faster for both IOPS and bandwidth metrics.

For comparison, the native speed on macOS was 28.6k IOPS and 117MB/s bandwidth.

Conclusion

After testing Colima I found it to be a great drop-in replacement for Docker Desktop. It even has faster performance for shared folders, which is another good argument to switch.

I did not notice any difference when running docker containers and all docker commands worked the same as before, which is great since none of my build-scripts had to be changed.