Some Linkerd service mesh users will soon have to pay
Companies with more than 50 employees using Linkerd service mesh in production must pay Buoyant for stable releases starting in May. Open source users and analysts weigh in.
The CNCF's Linkerd service mesh project will soon change its approach to open source code distribution in order to fund the project's future development.
The first version of the Linkerd project pre-dated its chief competitor, Istio. Linkerd's original developers coined the term service mesh. The Kubernetes-based Linkerd version 2 lagged Istio in advanced security features and support for workloads running outside container clusters -- the latter has been added just this week with version 2.15 -- but won proponents due to its relative simplicity and ease of use.
However, that hasn't been enough to keep the project viable for the long-term, according to William Morgan, CEO at Buoyant, a vendor that employs all of Linkerd's core maintainers and sells commercial and SaaS support for the project.
William Morgan
"There has to be some way of connecting the businesses that are being built on top of Linkerd back to funding the project," Morgan said. "If we don't do that, then there's no way for us to evolve this project and to grow it in the way that I think we all want."
Beginning May 21, any company with more than 50 employees running Linkerd in production must pay Buoyant $2,000 per Kubernetes cluster per month to access stable releases of the project.
One member of the Linkerd community, a current Linkerd Ambassador, said he plans to evaluate it for future projects despite the changes.
"The health of Buoyant is a concern for a lot of folks looking to adopt Linkerd. They are the stewards of the project and the ones doing most of the work," said Chris Campbell, staff software engineer at Dutchie, an ecommerce software provider to cannabis retailers in Bend, Ore. "Based on sticker price, Linkerd is still going to be cheaper than their biggest competitors in Istio, based on quotes we got from them."
The project's overall source code will remain available in GitHub, and edge, or experimental early releases of code, will continue to be committed to open source. But the additional work done by Buoyant developers to backport minimal changes so that they're compatible with existing versions of Linkerd and to fix bugs, with reliability guarantees, to create stable releases will only be available behind a paywall, Morgan said.
"That's the model that we've been operating under this entire time," he said. "It's just, what do you want to consume as the end user of the software? Do you want to consume something that is on the bleeding edge, or do you want to consume something that contains the minimum changes to reduce risk in production? That's the distinction we're making."
Morgan said he is prepared for backlash from the community about this change. In the last section of a company blog post FAQ about the update, Morgan included a question that reads, in part, "Who can I yell at?"
Campbell said the change could hurt as well as help the project.
"This [gives me] more faith that [Buoyant] will be able to stay afloat … but you can't help but feel that this will hurt adoption," he said.
Open source in name only
Morgan emphasized that the change to stable release distribution is not a change to the service mesh project's license, as with HashiCorp's switch to a business source license last year. But industry watchers flatly pronounced the change a departure from open source.
"By saying, 'Sorry but we can no longer afford to hand out a production-ready product as free open source code,' Buoyant has removed the open source character of this project," said Torsten Volk, an analyst at Enterprise Management Associates. "This goes far beyond the popular approach of offering a managed version of a product that may include some additional premium features for a fee while still providing customers with the option to use the more basic open source version in production."
Open source developers outside Buoyant won't want to contribute to the project -- and Buoyant's bottom line -- without receiving production-ready code in return, Volk predicted.
Morgan conceded that these are potentially valid concerns and said he's open to finding a way to resolve them with contributors.
"That's certainly a feeling they could have," he said. "I don't think there's a legal argument there, but there's an unresolved tension there, similar to testing edge releases – that's labor just as much as contributing is. I don't have a great answer to that, but it's not unique to Buoyant or Linkerd."
There has been friction between philosophical open source ideals and corporate business priorities as open source software has become ubiquitous in enterprise IT. Multiple companies have changed their approach to open source in recent years to fund product development. Most recently, developer app monitoring vendor Sentry switched to a delayed open source model in January, citing an "open source sustainability crisis."
Campbell agreed that the issue goes beyond Linkerd.
"I think this is always an issue for open source first companies, how to monetize the work, but keep true to the spirit of open source," he said. "Not sure many have been able to do very well without leaning into proprietary features."
Still, Linkerd is now effectively "open source in name only," said Rob Strechay, lead analyst at enterprise tech media company TheCube. "This could be the death knell to the open source [project]."
In the shadow of Istio
Another industry analyst said this move reflects an increasingly sharp contrast between Linkerd and chief rival Istio in terms of adoption and momentum.
An estimated 5,000 companies use Linkerd, according to Morgan. Recent estimates of the number of Istio users aren't readily available, but Istio has 8,800 individual open source contributors, including 85 maintainers from 15 different companies. IstioCon virtual events in 2021 and 2022 attracted more than 4,000 attendees each, according to a Cloud Native Computing Foundation (CNCF) blog post. The Envoy proxy alone has more than 300 companies contributing. Two commercial vendors, Solo.io and Tetrate, have also emerged with products that offer enterprise Istio support.
"Whether [Buoyant] calls it $2,000, or $1,000 or $5,000, I don't know if it matters in the big scheme of things," said Vijay Bhagavath, an analyst at IDC. "You can quote these amounts as a market leader with real traction. [But] in this case, adoption is lagging. Getting somebody to pay real money while they are significantly lagging Istio in terms of production adoption with bigger enterprises -- they have a hurdle to cross here."
By saying, 'Sorry but we can no longer afford to hand out a production-ready product as free open source code,' Buoyant has removed the open source character of this project.
Torsten VolkAnalyst, Enterprise Management Associates
Linkerd has always trailed Istio in support for advanced security features such as mutual TLS, which Istio had at launch in 2017. Linkerd first added it in experimental form in 2019. Linkerd made up for this in its early years with its ease of use, but Istio maintainers have since at least partially closed that gap.
Most notably, Istio introduced Ambient Mesh, a sidecarless, simplified alternative to the full-service mesh implementation, in 2023. Morgan and other Buoyant officials initially dismissed Ambient Mesh in public comments as a problematic workaround for the Envoy proxy, touting Linkerd's lightweight Rust proxy as an alternative.
Morgan's blog this week indicated Linkerd is considering an ambient approach to service mesh as part of its future roadmap, along with ingress traffic, egress control and eBPF support -- all features Istio and Envoy already offer. Another previous distinction between the two, governance by the CNCF for Linkerd -- Istio remained separate -- also disappeared when Istio was donated to the foundation in 2022.
Buoyant's funding gambit isn't necessarily the wrong move if existing Linkerd users get a sustainable, reliable product, Strechay said. But it does mean scrutiny on the project will intensify. Buoyant could seek acquisition by a larger vendor, similar to Cisco's acquisition of Isovalent for eBPF networking and service mesh in December, he said.
"It doesn't mean an enterprise version will fail. But it is probably the only way to survive and get more funding," Strechay said, "which puts them and the technology on the clock."
Beth Pariseau, senior news writer at TechTarget, is an award-winning veteran of IT journalism. She can be reached at [email protected] or on X, formerly Twitter, @PariseauTT.
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