New Base Config to Run Directly from Container Images

We just shipped a change to how base images work on RWX.

Previously, your CI/CD runs could only use one of two base images, ubuntu 22.04 or ubuntu 24.04, defined in a section at the top of your run configuration like this:

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base:
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  os: ubuntu 24.04
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  tag: 1.2

We built these base images by taking the default container images for Ubuntu, installing common packages, making a few quality-of-life configuration changes, and adding support for running Docker.

Unlike GitHub Actions which uses a bloated 47 GiB base image, we strived to keep our image as small as possible while still providing a great out-of-the-box experience.

This approach worked well, but we wanted to open up the RWX runtime to support base images beyond Ubuntu.

#New Base Image Configuration

We're deprecating the os and tag configuration. You can now configure base images directly from container images, like this:

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base:
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  image: ubuntu:24.04
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  config: rwx/base 1.0.0

The image can be a reference to any Docker image. Note that the syntax changed from a space to a colon (ubuntu 24.04 to ubuntu:24.04) to match the standard container image:tag syntax.

The previous customizations that were baked into the RWX base images are now applied via an RWX package. It is open source and you can see the code on GitHub.

Currently, the rwx/base package only works for ubuntu 22.04 and ubuntu 24.04. However, you can skip the base configuration entirely and then use any base image:

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base:
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  image: debian:trixie
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  config: none
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tasks:
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  - key: os-release
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    run: cat /etc/os-release

#RWX as a Container Runtime

We made this change in conjunction with providing the ability to build container images directly from the RWX runtime. Clearly, to provide a faster and more ergonomic experience for building container images, we needed to support running from any base image. Implementing support for this also required removing previously hard-coded assumptions around the shell, user, and workspace, enabling even greater flexibility.

#Exporting Containers Images

RWX implicitly generates container images for every individual step in a pipeline. You can run rwx pull to pull the image for any task within any pipeline. We're able to build these images extremely quickly due to having developed an entirely new container runtime that removes many of the performance limitations imposed by Docker. See the docs on building container images.