INTERVIEW Gregory Kurtzer, CentOS’s founder, tells the story of how the Red Hat Enterprise Linux clone was born of a small group of rebuild hackers and Linux fans who were angry that Red Hat Enterprise Linux had replaced Red Hat Linux and convinced they could do better.
Back in 2003, Linux fans were ticked off at Red Hat because they were replacing the end-user-friendly Red Hat Linux with the business-oriented Red Hat Enterprise Linux (RHEL). It was a smart move for Red Hat, but users were pissed when then Red Hat CEO, Matthew Szulik, said that for home users, Windows was probably “the right product line.” Yeah. That went over about as well as you’d expect.
In the meantime, Gregory Kurtzer had no plans to start building a Linux distribution, he says. He came out of biochemistry and genomics, where compute‑hungry (Basic Local Alignment Search Tool) (BLAST) jobs were chewing through early SGI systems. One day, his business partner suggested they try Linux.
“He said there was this thing called Linux, he wanted to try, and I thought he was mispronouncing Unix,” Kurtzer tells The Register. They drove to Fry’s, “bought a ton of hardware,” and discovered that a free operating system downloaded off the internet could run serious scientific workloads.
It wasn’t the price that blew his mind, says Kurtzer. What hooked him was realizing that “many, many thousands of people [were] collaboratively working all over the world on a common software project… actually creating something of massive amounts of value.” He became “enamored with open source in general, but Linux as a platform,” and started looking for ways to contribute.
When he landed at the Department of Energy’s Berkeley lab, the environment was standardized on Red Hat. He says he missed Debian’s ecosystem and apt so much that he began asking why there was “no community around the Red Hat type ecosystem or the RPM-based ecosystem.” The answer he kept hearing was that Red Hat owned that space. His answer was Caos [Community Assembled Operating System].
The idea was “to be basically a Debian-like alternative for RPM-based distributions of Linux.” Caos used Red Hat as a base. “Glibc came out of Red Hat, for example, right, but we used the upstream kernel and then extended it with a community‑driven package universe.” He formalized the effort as the Caos Foundation, a 501(c)(3) non‑profit.
Caos might have stayed a small Linux distro like so many others, but when Red Hat ended the classic Red Hat Linux line in favor of RHEL, it picked up steam. Kurtzer recalls that the community had grown up on free Red Hat Linux CDs, and the move landed badly: “Linux is a community project, it’s freely available, and it should remain freely available, so a lot of people didn’t like that notion at the time.”
By then, there was already a Red Hat “rebuild” mailing list where multiple groups were experimenting with re‑compiling Red Hat’s source packages into community distributions.uKurtzer tell is: “VA Linux was doing this, along with an HPC company called Atipa, which is where early CentOS developer Rocky McGaugh worked… and there were a few others.”
Rocky, later immortalized in the name Rocky Linux, was part of that loose coalition, maintaining his own rebuilds. The list also included John Morris, who’d create White Box Enterprise Linux, and David Parsley, who would launch Tao Linux.
The first RHEL clone to break out wasn’t CentOS; John Morris’s White Box Enterprise Linux, not CAOS or CentOS, was first. “He released White Box Enterprise Linux, and Slashdot went crazy for it,” Kurtzer remembered.
Sudden success became a burden. Morris “got way more visibility and attention and responsibility than… he was ready to take on” and didn’t want to “take on the weight of the world in terms of infrastructure.” The Caos folks, by contrast, already had build and mirror infrastructure: “we already have our own builders, we already have our own infrastructure… we were already ingesting packages from… Red Hat Linux [and] Red Hat Enterprise Linux.”
At a supercomputing conference… I was talking with a vendor… and I remember somebody came up next to me and interrupted the conversation to ask the vendor: ‘Why don’t they support CentOS?’
“So a couple members of the Caos team said, well, we’re already kind of doing a lot of this… It’s like, well, this actually makes sense, because we can then leverage those same binaries… and let’s start this project, and so CentOS kind of came out of everything that was happening at the time.”
Then the Red Hat clones were more collaborative than competitive: “We were generally all very collaborative… we were all kind of on the same IRC list, so when any of us had a bug on rebuilding a package or issue, we all kind of worked together.”
Where Caos had an edge was scale. “We actually had a number of people already associated with it. We already had a critical mass… so it was not that big of a lift for us to properly support this,” Kurtzer says.
Parsley ultimately “ran Tao Linux… for quite a while before finally retiring the project, and then telling his users basically to go… over to CentOS,” complete with a “nice transition plan.” White Box and Tao quietly funneled users and expectations into the emerging CentOS brand.
Even the version numbers reflect CentOS’s pragmatic roots. “CentOS 3 was developed almost completely by Rocky,” Kurtzer adds. “We started CentOS version 3 before version 2, and there was never a 1, right, because… There was never a version 1 of RHEL either.” CentOS 3 arrived on stage on March 19, 2004.
The community went where the demand was. “We identified that the first and most pressing need was around version 3, so Rocky started with version 3. That focus, combined with Caos’s infrastructure and the consolidation of smaller rebuilds, turned CentOS into the RHEL clone that stuck.”
For its early life, CentOS lived under the Caos Foundation umbrella. By the CentOS 4 timeframe, in 2005, the projects split. Kurtzer says, “At about the release of… CentOS four… the CentOS project left the Caos Foundation, and it moved on… and we kind of ended up going different directions.”
He ceded control. “I was no longer the project lead of CentOS at that point, so it was taken over by a guy named Lance Davis,” he tells The Reg. Caos continued until around 2007–2008, including a “Node Server Appliance” variant focused on “lightweight high-performance computing systems,” but the market was voting with its feet. “Most people wanted the compatibility… that one-to-one compatibility… was incredibly important,” he says. CentOS became the canonical RHEL clone; Caos faded into history.
How CentOS simply had to exist
From the outside, CentOS often gets cast as Red Hat’s free rival. Kurtzer sees it differently. Red Hat’s subscription model, he contends, practically required something like CentOS to exist. “This choice in the business model has made it very difficult for organizations, and so this is the whole reason why… There was even a need for CentOS,” he says.
Kurtzer explains that enterprises evolved a two‑tier pattern. “Organizations started running a bisected environment where they ran CentOS on the majority of it, and then they ran Red Hat on a sliver of it, where they needed the most support, where they needed validation, where they needed to know that it’s going to work.”
Without CentOS, he bluntly says: “I believe that most organizations probably would have gone to a Debian and Ubuntu model because nobody’s going to pay for support… across their whole environment for a free product.” Running Debian or Ubuntu everywhere and RHEL on a small slice doesn’t work well, he argues, because “it’s an incompatible operating system, so the tooling would be different depending on what side of the infrastructure that they’re looking at.”
With CentOS, they could “run the free product where they can and then only pay for the support where they need to.” His conclusion: “I actually truly believe CentOS was very helpful to RHEL overall, given the choice of that particular business model.”
I thought that this was a really fair option for [the CentOS] to now get hired by Red Hat… and now get paid, and now be… not having to give up their home life.”
Asked when CentOS stopped being a niche rebuild and became a default choice, Kurtzer points to a supercomputing conference in Phoenix in the mid-2000s. “I remember being at a supercomputing conference… and I was talking with a vendor… and I remember somebody came up next to me and interrupted the conversation to ask the vendor: ‘Why don’t they support CentOS?’”
It was a turning point. “This is the first time I actually even heard somebody outside of my circle of people actually now start demanding CentOS… and it was somebody I didn’t know, and I’m just kind of like, ‘wow, that was kind of cool.’” Around the same time, Kurtzer says he and early collaborators met IBM executives there to pitch Caos and CentOS. “Interestingly enough, there was no interest at the time. Another metric of success was seeing technology appear on resumes and in job descriptions. By the mid‑2000s, CentOS was on its way to being more popular than RHEL.”
By the early 2010s, CentOS was everywhere, but still maintained by a small, unpaid team. When Red Hat moved to sponsor the project in 2014, some read it as a hostile capture. Kurtzer didn’t.
“The CentOS team was fairly small at this point… and the developers were basically doing heroic feats for the entire community, and not being paid for it.” Some things never change in open source, do they?
Kurtzer says he thought the deal was fair. “They’re giving up their home lives and whatnot… and there were companies out there that were doing very well, basing their infrastructure on it, but also making a ton of money on that, so I thought that this was a really fair option for them to now get hired by Red Hat… and now get paid, and now be… not having to give up their home life.”
Vendors began calling to ask if CentOS was going away and whether he’d recreate it. “I even had two people from fairly large companies at fairly high rankings… basically say, ‘Greg, do you want to recreate CentOS?’ And I said, ‘no… let’s give Red Hat… the benefit of the doubt… and see what happens,’” he recalls. For years, he thinks, Red Hat did “a phenomenal job”: release latency improved, documentation and community interaction got better.
That’s why the CentOS 8/CentOS Stream pivot in 2021 hit so hard. Kurtzer thinks that Red Hat’s messaging “was just a complete cluster… nobody, including the people at Red Hat, really knew what they were saying.” The community’s “general consensus at the time was that CentOS is end of life, and there’s this new thing that’s replacing it, which is some rolling beta.” The blog post announcing the change “got more press… and more comments than any other blog that Red Hat has ever posted… mostly people in the community yelling at Red Hat,” and “it was… nasty.”
By then, Kurtzer was running CIQ, a young high-performance computing (HPC) company building a computing platform on CentOS. They had already asked themselves what would happen if “something happens to CentOS.” Their answer was to be ready to help rebuild a RHEL‑compatible distro if needed.
Within two hours of the CentOS blog going live, as comments piled up, Kurtzer says, he replied publicly: “Hi everybody, I’m… original founder of CentOS. I’m going to go… recreate CentOS, and I’m hanging out over in this Slack over here… and if anybody wants to join me, I’ll be hanging over there, kind of thinking about how to do this.”
The response was immediate. “Within four to six weeks, we had over 10,000 people join… it took off,” he says. The free tier of Slack couldn’t cope, “that 10,000 message limit goes in a matter of hours,” but it was enough to bootstrap a new community. Teams coalesced around release engineering, testing, development, branding, web work, and even merchandise. “We had T‑shirts, swags, and memorabilia that you can get before we had any code,” he laughs. Early shirts read “Rocky Linux” with “early supporter” in brackets underneath.
Rocky Linux wasn’t the only successor; AlmaLinux and others joined the field, and the usual distro tribalism followed. Kurtzer compares it to sports rivalries: “We just do it around our Linux distribution choices,” he says. But he insists the diversity is healthy. “If something happens to Alma, Rocky’s here; if something happens to Rocky, Alma is there; if something happens to both of us, Oracle is there; and we have all of these other options to guarantee the stability in the ecosystem.”
That may be CentOS’s real legacy. It proved that a community could rebuild an enterprise OS from source and sustain it long enough for enterprises to standardize on it, and that doing so could actually reinforce, not undermine, the commercial platform it tracked.
The clones that followed, from Scientific Linux to Rocky and Alma, are part of the same lineage that began when a few people on a rebuild mailing list decided that Red Hat’s sources shouldn’t just sit on a server; they should become a truly community Linux again. ®
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