The project, which recently graduated, asks poignant questions about its future.


DENVER —  At the first Open Infrastructure Summit, continuous integration/continuous delivery project Zuul crossed the threshold to independent project status along with Kata Containers.

After graduation, now what? James Blair, Zuul maintainer and office of the CTO, Red Hat says that like all new grads, the project gating system is asking a lot of important “What if?” questions:

  • What if we make this change?
  • What if we upgrade this dependency?
  • What happens to the whole system if this micro-service changes?
  • What if the base container image changes?

Zuul is a project under the OSF’s CI/CD strategic focus area. The community is busy adding new features but one especially worth focusing on is changing the way people develop containerized software.

Zuul is more than CI/CD, Blair says. It’s a new way of testing that gives developers freedom to experiment, is called speculative execution. “We’ve done it for years with Git, but now we can do it with containers,” he adds.

Here’s why that’s important.

Container images are built on layers. In the stacked image system, the registry is intermediary. This can lead to images in production with inadequate testing and upstream images breaking downstream. “We want to know that changes to base images won’t break the images composed on top,” he says.

With Zuul speculative container images, registries are created as needed. Registries are ephemeral, lasting only as long as each test. Every deployment sees its future state, including the layers it depends on. And this process is invisible to deployment tooling. Test jobs use Zuul’s registry and speculative or production images. When images have been reviewed and pass tests, they’re safe to promote to production.

A key design point: You can use actual production deployment tooling in tests. Zuul speculative container images makes testing more like production, not the other way around. Zuul allows its users to move fast without fear, because its speculative execution feature allows them to find issues and verify solutions in complex systems before committing a single change to production.

Catch the whole six-minute presentation below and check out the other Zuul talks from the Summit.

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