As application and platform engineers, we have experienced the challenge of keeping Docker container build times fast. From optimizing and reoptimizing Dockerfiles, to implementing layer caching in CI, to running & maintaining custom runners for multi-platform images.

Still today, there are limitations with the available tools. CI runners are ephemeral, and saving and loading cache tarballs is slow. CI providers are resource constrained, with limited CPUs and disk space to dedicate to fast builds. And with the increasing popularity of Arm devices like M1, Graviton, etc, building multi-platform images requires slow emulation or self-hosted infrastructure.

We created Depot to directly address those limitations. Depot provides managed VMs running BuildKit, the backing build engine for Docker. Each VM includes 4 CPUs, 8GB of memory, and a persistent 50GB SSD cache disk. We launch both native Intel and native Arm machines, on Fly.io for Intel builds and AWS for Arm.

We have built a depot CLI that embeds the Docker buildx build library, implementing the same CLI flags, so developers can send their builds to Depot VMs just by replacing `docker buildx build` with `depot build`. We also have a depot/build-push-action GitHub Action that can be swapped for docker/build-push-action in CI.

The combination of native CPUs, fast networks, and persistent disks significantly lowers build time — we’ve seen speedups of 2-3x on optimized projects, and as much as a 12x speedup with some of our customers.

We believe that today we are the only hosted CI or build service offering the ability to natively build multi-platform Docker images (--platform linux/amd64,linux/arm64) without emulation.

We are still early though, and would love your feedback.

You can sign up without a credit card at https://depot.dev/sign-up to access a free project with thirty days of unlimited build minutes to try it out.