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Early this month, a small patch appeared in the Zuul project’s code review queue on OpenDev: change 1,000,000, a six-line optimization to how Zuul checks GitHub repository permissions. The author was James “Jim” Blair, the founder of Zuul and one of the earliest engineers to work on OpenStack’s build and test systems.
The number is a coincidence of timing. The contributor is not: Blair also submitted change 1, an SSH-hardening puppet module, on July 18, 2011. Over 15 years and 999,999 changes later, the same engineer closed the loop on a system he helped build from its first commit.
For readers of Superuser, that arc is worth pausing on, because OpenDev is the infrastructure that makes most of the OpenInfra Foundation’s software possible, even though most users never see it.
What OpenDev is
OpenDev describes itself as “a collaboratory for open source software development at a huge scale,” built on the idea that free software needs free tools. It provides code review, continuous integration and project hosting entirely through open source components, including Gerrit for review, Zuul for testing and gating, and Gitea for browsing repositories.
The system’s defining feature is that it applies its own principles to itself. Anyone can propose a change to how OpenDev’s servers are configured, without shell access or special permission, just as they would to any hosted project’s code. Production changes are driven by a reviewed and tested patch, not by a manual login. Blair’s first commit, hardening SSH access on the very system he later helped scale, is an early example of that pattern.
From OpenStack Infra to OpenDev
The system began as the OpenStack Project Infrastructure team, and its Gerrit review history stretches back to 2011. By 2018, that team was already supporting projects beyond OpenStack, such as Zuul and StarlingX. Clark Boylan, now a senior principal engineer at the OpenInfra Foundation, led the effort to rename the team that November at the OpenStack Summit in Berlin.
“We are not calling the infrastructure OpenStack, to make it clear that it is not OpenStack,” Boylan said at the time, according to ServerWatch. “Effectively, we will become the OpenDev infrastructure team rather than the OpenStack Infrastructure team.” The rename gave every hosted project equal footing under a neutral name, and git repositories migrated to opendev.org through 2019.
The underlying workflow is older than either name, according to Blair. “The workflow itself predates OpenDev and OpenStack,” he said, pointing to precursor projects like Drizzle that first showed the value of a gating model, where “users are empowered to make decisions about what changes to merge, and computers do the work of making sure none of those changes break the codebase.” What changed for OpenStack, he said, was scale: “We scaled it massively and used new tools fit for the purpose: Gerrit and Zuul,” both of which have “grown significantly” since and “excel at multi-project development tasks partly because many of the largest software projects in the world use them daily and they keep raising the bar.”
Zuul itself grew out of that same team’s need to test a fast-growing volume of OpenStack patches. As Jeremy Stanley, also a senior principal engineer at the OpenInfra Foundation, wrote in a 2020 piece for Opensource.com, republished on Superuser: “CI is, at the most fundamental level, about integrating the work of multiple software development streams into a coherent whole with as much frequency and as little friction as possible.” Zuul’s “speculative execution” model—testing multiple proposed changes in parallel before any of them are merged—let OpenStack move past a ceiling of roughly two dozen changes per day to a burst of hundreds per day, which would not have been possible without this functionality.
Boylan traces the tooling choices of that era to necessity as much as design. “Back then GitHub was new, and Launchpad didn’t support git repositories,” he said. “Systems like Gitea/Forgejo didn’t exist. The tools we chose were often out of necessity, picked because they solved problems that OpenStack faced.” That has shifted, he said: “As GitHub and others’ capabilities have improved, we’re seeing more people who choose to use OpenDev’s systems not out of necessity but because they prefer the workflow for code review and CI.”
Scale, by the numbers
Boylan and Stanley offered a current accounting of OpenDev activity: almost 12,000 individuals have pushed code to OpenDev’s Gerrit since 2011, and more than 9,000 people have reviewed a change in Gerrit. A millionth submitted change, spread across roughly a decade and a half, reflects steady, compounding volume rather than any single burst of activity.
OpenDev isn’t the only Gerrit installation to reach that scale. Boylan pointed to the Wikimedia Foundation’s Gerrit instance, which also crossed a million changes despite an earlier attempt to move off the platform, as a sign of “continued interest in this style of code review.” By his estimate, OpenDev’s own pace has cooled from a peak of roughly 100,000 changes every nine months between 2015 and 2017, coinciding with OpenStack’s fastest growth, to closer to 100,000 changes every two to two-and-a-half years now. “That reflects the peak of the hype curve for OpenStack, then a gradual transition into more steady-state maintenance,” he said. “The need for these tools hasn’t gone anywhere; they’re essential at every stage of a project’s lifecycle.”
Who keeps it running
OpenDev is maintained by a small team including OpenInfra Foundation engineers (Boylan and Stanley), alongside volunteer contributors from companies such as Red Hat, Acme Gating, OSISM GmbH, and StackHPC. Compute and storage resources are donated by infrastructure contributors, including Vexxhost, Rackspace, OVHcloud, OpenMetal and OSUOSL. The OpenInfra Foundation became part of the Linux Foundation in 2025, though OpenDev’s day-to-day operation has continued under the same engineering team.
Blair, for his part, has framed the project’s design philosophy as one of restraint. “We care more about the development process to the point that we’re perfectly willing to sacrifice that and be as invisible as possible,” he told Superuser earlier this year for a piece on what AI-era developers can learn from a decade of open source CI.
That openness has a self-serving upside for the people who maintain it, Blair said: it’s fun. “A lot of the work that happens in OpenDev happens because people see something they want to change, and they can just make it happen,” without needing to ask permission or wait on someone else’s schedule, he said. OpenDev’s own infrastructure testing, built around Zuul, is “so robust that with a patch to the Ansible playbooks that run everything, you can see an entirely new system brought online in CI, tested, and then destroyed. It’s addictive for developers and sysadmins to have that kind of confidence in system changes and also not have to clean up afterward.”
Why it matters
In addition to core OpenInfra Foundation projects OpenStack, Zuul and StarlingX, hundreds of smaller, loosely affiliated repositories depend on OpenDev for code review and testing and use it for free. For the operators and contributors who make up Superuser’s audience, OpenDev is why those projects can credibly claim to practice the “Four Opens”: every dependency, every infrastructure change, and every test result is public.
The model may matter even more as software development shifts toward AI-assisted and agentic coding, Boylan said. “Theoretically, the bot armies are being tasked with building complete software systems,” and making that work requires agents to collaborate much the way OpenDev was built to let thousands of human developers collaborate on OpenStack, he said. “Reviewing each change gives you auditability beyond what ends up in the final git branch. Gating ensures that everyone stays in sync and the software is operable at any point in time.” GitHub and GitLab have added merge queues of their own, he noted, but they’re narrower in scope: GitHub requires a separate branch for each queue entry on a single repository, and GitLab caps queues at 20 entries, with neither supporting the cross-project queues OpenDev’s tools allow.
Blair sees a related advantage in flexibility. “OpenDev is focused on free and open source software, but Zuul works with GitHub and GitLab too,” he said. Because Zuul can layer its gating workflow on top of any code review system, or connect more than one at once, teams aren’t locked into a single vendor. “That’s a level of openness that closed development environments will never offer,” he said.
How to help
Getting involved requires no special access. New contributors can follow the OpenDev Manual’s getting-started guide to create a Gerrit account and propose a change, join the community on Matrix, or subscribe to the project’s mailing lists. Individuals who want to support the foundation’s work more broadly can also join the OpenInfra Foundation as individual members at no cost, while organizations can contribute compute and storage resources, as OpenDev’s existing donors already do.
Boylan credits that continuity to the people who keep showing up. “OpenDev is possible because its users get involved and help make it happen,” whether through donated cloud resources or donated systems-administration time, he said. “I would like to thank everyone who has made OpenDev possible over the years,” he added, encouraging anyone interested in code review, CI, or open collaboration to get involved. “We work in the open. It is a great place to learn, and we’re always happy to have help. Open source doesn’t happen only on GitHub, and ensuring we continue to have a vibrant set of options for software development in the open is important to ensure open source has options well into the future.”
A million changes in, the system Blair helped start in 2011 is still running on the same premise: that infrastructure, like any other software, should be built in the open, one reviewed patch at a time.
- The One Millionth Change: OpenDev’s Quiet 15-Year Marathon - September 2, 2026
- How the University at Buffalo Modernized Its Research Cloud with OpenStack - August 10, 2026
- Canonical Helps Nova Build an Open Source Telco Cloud - July 21, 2025
