The Linux Foundation last week announced that it will host Valkey, a fork of the Redis in-memory data store. Valkey is supported by AWS, Google Cloud, Oracle, Ericsson, and Snap.
AWS and Google Cloud rarely support an open source fork together. However, when Redis Labs changed Redis away from the permissive 3-clause BSD license on March 20 and adopted the more restrictive Server Side Public License (SSPL), a fork was always one of the most likely outcomes. At the time of the license change, Redis Labs CEO Rowan Trollope said he “wouldn’t be surprised if Amazon sponsored a fork,” as the new license requires commercial agreements to offer Redis as a service, making it incompatible. with the standard definition of “open source”.
It’s worth taking a few steps back to see how we got to this point. After all, Redis is among the most popular data stores and is the core of many large commercial and open source implementations.
A brief history of Redis
Throughout its life, Redis has seen some licensing disputes. Redis founder Salvatore Sanfilippo launched the project in 2009 under the BSD license, partly because he wanted to be able to create a commercial fork at some point and also because “the BSD [license] allows many branches to competewith different licensing and development ideas,” he said in a recent hacker News comment.
After Redis quickly gained popularity, Garantia became the first major Redis service provider. Garantia changed its name to RedisDB in 2013, and Sanfilippo and the community pushed back. After a while, Garantia finally changed its name to Redis Labs and then in 2021to Redis.
Sanfilippo joined Redis Labs in 2015 and later transferred its intellectual property to Redis Labs/Redis, formerly lower from the company in 2020. That was just a couple of years after Redis changed the way it licenses its Redis modules, which include visualization tools, a client SDK, and more. For those modules, Redis first opted for the Apache license with the addition Commons Clause which prevents others from selling and hosting these modules. At the time, Redis said that despite this change in modules, “the open source Redis license was never changed. It is BSD and it will always be BSD.” That commitment lasted until a few weeks ago.
Redis’s Trollope reiterated in a statement what he had told me when he first announced these changes, emphasizing how large cloud providers benefited from the open source version and are free to enter into a commercial agreement with Redis.
“All the major cloud service providers have benefited commercially from the Redis open source project, so it is not surprising that they are launching a fork within a foundation,” he wrote. “Our license change opened the door for CSPs to establish fair licensing agreements with Redis Inc. Microsoft has already reached an agreement and we are happy and open to creating similar relationships with AWS and GCP. We remain focused on our role as stewards of the Redis project and our mission to invest in the available Redis source product, ecosystem, developer experience, and serving our customers. “Innovation has been and always will be the differentiating factor between the success of Redis and any alternative solution.”
Cloud providers backed Valkey
The current reality, however, is that the big cloud providers, with the notable exception of Microsoft, were quick to support Valkey. This fork originated on AWS, where long-time Redis maintainer Madelyn Olson initially started the project on her own GitHub account. Olson told me that when the news broke, many of the current Redis maintainers quickly decided it was time to move on. “When the news broke, everyone said, ‘Well, we’re not going to contribute to this new license,’ and as soon as I talked to everyone, ‘Hey, I’ve got this fork, we’re trying to keep the old group together,'” he said. “Almost everyone said: ‘Yes, I’m on board immediately.'”
The original Redis private channel included five maintainers: three from Redis, Olson, and Alibaba. Zhao Zhao, as well as a small group of commits who also immediately signed on to what is now Valkey. As expected, Redis maintainers didn’t sign up, but as David Nally, director of open source strategy and marketing at AWS, told me, the Valkey community would welcome them with open arms.
Olson noted that he always knew that this change was a possibility and was within the rights of the BSD license. “I’m more disappointed than anything else. [Redis] “He had been a good administrator in the past and I think the community is a little disappointed with the change.”
Nally noted that “from an AWS perspective, it probably wouldn’t have been the choice we wanted to see in Redis Inc.” But she also acknowledged that Redis is within its rights to make this change. When asked if AWS had considered purchasing a Redis license, she gave a diplomatic response, noting that AWS “considered a lot of things” and that nothing was off the table in the team’s decision-making.
“It’s certainly their prerogative to make that decision,” he said. “While we have made some other decisions about where we are going to focus our energy and time as a result, Redis remains an important partner and customer, and we share a large number of customers between us. And that’s why we hope they succeed. But from an open source perspective, we are now committed to ensuring the success of Valkey.”
It’s not often that a fork forms so quickly and can gather support from so many companies under the auspices of the Linux Foundation (LF). That’s something previous Redis forks like KeyDB didn’t have going for them. But it turns out that some of this was also fortuitous timing. The Redis announcement came right in the middle of the European version of the Cloud Native Computing Foundation’s KubeCon conference, which was held in Paris this year. There, Nally met with LF executive director Jim Zemlin.
“It ruined KubeCon for me because all of a sudden I ended up in a lot of conversations about how we respond,” he said. “[Zemlin] He had some concerns and volunteered to the Linux Foundation as a potential home. So we went through the process of introducing Madelyn. [Olson] and the rest of the maintainers to the Linux Foundation, just to see if they thought it was going to be a compatible move.”
Whats Next?
The Valkey team is working to release a compatibility version that provides current Redis users with a transition path. The community is also working on an improved shared clustering system, improved multithreading performance, and more.
With all this, Redis and Valkey are not likely to remain aligned in their capabilities for long, and Valkey may not remain a direct replacement for Redis in the long term. One area that Redis (the company) is investing in is going beyond memory to also use flash storage, with RAM as a large, high-performance cache. That’s why Redis recently acquired Speedb. Olson noted that there are no concrete plans yet for similar capabilities in Valkey, but he didn’t rule it out either.
“There’s a lot of excitement right now,” Olson said. “I think previously we were a little technologically conservative and trying to make sure we didn’t break things. Whereas now I think there is a lot of interest in building a lot of new things. We still want to make sure we don’t break things, but there’s a lot more interest in updating technologies and trying to make things faster, more efficient, and more memory dense. […] I think that’s something that happens when a changing of the guard happens because a group of previous maintainers are basically no longer there.”