ARM/M1 + Tilt = ❤

Ways to set the right platform for your images

Maybe you got a fancy new MacOS M1 laptop and now you’re getting cryptic errors when you build your app.

Or maybe you’re trying out EC2 Graviton machines in your dev cluster, but now none of your images work right.

Welcome to the world of ARM processors! The x86 monoculture has been broken!

Better processors is good for the ecosystem in general. But now your dev environment has to handle the case where your host CPU is different from the target CPU.

Tilt has shipped a few small tweaks recently that we hope will help build for the right CPU without having to think about it.

Setting Platform Automatically

If you’re using Tilt to build Docker images with docker_build, we’ll now automatically read the architecture off the cluster and use that in the Docker build.

In the logs, you’ll see a line like this:

STEP 1/5 — Building Dockerfile: [tilt-site]
Building Dockerfile for platform linux/amd64:

We’ve detected that the cluster architecture is amd64 and will use this instead of your host architecture.

Setting Platform Manually

Maybe you want to force a particular architecture, or build multi-platform images in dev.

You can override the platform manually by:

• Setting the DOCKER_DEFAULT_PLATFORM env var before you run tilt.

export DOCKER_DEFAULT_PLATFORM="linux/amd64,linux/arm64"
tilt up

• Setting the DOCKER_DEFAULT_PLATFORM env var in your Tiltfile:

os.environ['DOCKER_DEFAULT_PLATFORM'] = 'linux/amd64,linux/arm64'

• Setting the platform argument for docker_build in your Tiltfile.

docker_build('fe', '.', platform='linux/amd64,linux/arm64')

Wiring it Yourself

One of our goals with Tilt is to expose every part of your dev environment as a Kubernetes-style API, so you can use it in your own scripts to make decisions in an automated way.

Our current solution is the Cluster API.

The default cluster object is what Tilt knows about the place it’s deploying images.

$ tilt describe cluster default
Name:         default
...
Spec:
  Connection:
    Kubernetes:
Status:
  Arch:  amd64

In this example, we’re using the default Kubernetes cluster connection.

If you want to get the architecture of that cluster only, you can use the CLI:

$ tilt get cluster default -o=jsonpath --template="{.status.arch}"
amd64

The Future

Stay tuned for future changes to the cluster API so that you can use cluster info in your dev env, reset the cluster, and create new ones!

Shout out to Nick Jüttner, Jérôme Petazzoni, and Nick Sieger for suggesting ideas on how to better support multiple architectures.