Colima: the minimal replacement for Docker Desktop

Ever since Docker Desktop changed is pricing model I’ve been using Rancher Desktop as a replacement. Its works fine but I recently noticed a few coworkers using Colima.

Note: For individual users Docker Desktop is still free

Colima, is short for Containers on Lima. Where Lima is a separate tool Which aims bring Linux virtual Machines to macOS and Linux. Apparently its used by Rancher Desktop and Podman Desktop under the hood. Colima is a minimal CLI with sensible defaults that provides container runtimes for macOS. Its compatible with the latest and greatest versions of Docker BuildKit & Compose.

Install with Homebrew to get started:

brew install colima docker

To start Colima with the default of 2CPU, 2Gib Memory and 60Gib Disk, run:

colima start

> colima start
INFO[0000] starting colima                              
INFO[0000] runtime: docker                              
INFO[0001] starting ...                                  context=vm
INFO[0013] provisioning ...                              context=docker
INFO[0014] starting ...                                  context=docker
INFO[0014] done

To setup Docker Compose you need docker-compose

brew install docker-compose

Setting up BuildKit takes a few more steps.

Step 1: Set the Docker Configuration Path

The first step is to set the DOCKER_CONFIG environment variable to specify where Docker should look for its configuration files. Typically, Docker uses ~/.docker/ as the configuration path. Run the following command:

export DOCKER_CONFIG=~/.docker/

Step 2: Create the Plugins Directory

Docker uses plugins to extend its functionality, and for BuildKit, the docker-buildx plugin is required. We need to ensure that the cli-plugins directory exists within the Docker configuration path. Create this directory with the following command:

mkdir -p $DOCKER_CONFIG/cli-plugins

Step 3: Download the Buildx Plugin

Next, download the appropriate Buildx binary for macOS. If you are using an Apple Silicon (ARM64) machine, you can use the following command to download the latest release:

curl -SL https://github.com/docker/buildx/releases/download/v0.17.0/buildx-v0.17.0.darwin-arm64 -o $DOCKER_CONFIG/cli-plugins/docker-buildx

For Intel-based macOS machines, you would replace arm64 with the appropriate architecture (amd64 for Intel Macs).

Step 4: Make the Buildx Plugin Executable

After downloading the docker-buildx plugin, ensure it is executable by running the following command:

chmod +x $DOCKER_CONFIG/cli-plugins/docker-buildx

Step 5: Build Using BuildKit

With Buildx now installed, you can start using BuildKit to build your Docker images. Simply set the DOCKER_BUILDKIT environment variable to enable BuildKit, then run the Docker build command as usual:

DOCKER_BUILDKIT=1 docker build -t app:latest .