Redis Changed Open Source License! Are Cloud Providers Really Freeloading off the Open Source Community?
Origin
On March 21, 2024, Rowan Trollope, CEO of Redis Inc., the company behind the famous key-value database open source project Redis, announced a change in the project's licensing type from the original BSD open source license to a dual license under RSALv2 and SSPLv1.
This license change was primarily aimed at protecting Redis Inc.'s commercial interests, preventing cloud providers from using the open source version to offer commercial Redis SaaS services. Such actions are not uncommon; companies like Confluent, MongoDB, and Elastic have made similar license changes to their open source projects to protect their interests. However, this move by Redis triggered anger among many developers, a significant reason being that the Redis community includes many external contributors, and such unilateral modifications of the license are seen as damaging to the community and harmful to these contributors.
So, who exactly is deeply involved in contributing to the Redis community?
In-depth
The chart below shows the contribution distribution of the OpenRank [1] top 10 developers in the Redis community every year since 2020. We can tell that the Redis community has been trending towards diversification. The contribution share of internal Redis developers has decreased from nearly 80% in 2020, and by the first quarter of 2024, the contribution share of the top 10 developers within Redis had dropped to less than 40%. Many companies, including AWS, Alibaba Cloud, Tencent Cloud, and Ericsson, have been deeply involved in contributing to the Redis community for years, with their contribution intensity increasing annually.
At the end of June 2020, Salvatore Sanfilippo (@antirez), the original author of Redis, announced in a blog post that he was stepping down from maintenance work of the Redis community, handing over the community maintenance tasks to Yossi Gottlieb (@yossigo) and Oran Agra (@oranagra) from the then-called RedisLabs. At the same time, the aforementioned duo published an article stating the initiation of a new community governance model, and together with Itamar Haber (@itamarhaber), formed the core development team of the Redis community. The following month, Madelyn Olson (@madolson) from AWS and Zhao Zhao (@soloestoy) from Alibaba Cloud joined the core development team, which remained stable until the recent license change of Redis.
Besides the six core developers mentioned above, Zhu Binbin (@enjoy-binbin) joined the Tencent Cloud database product department due to his long-term involvement in Redis community. In addition to Zhao Zhao, Alibaba Cloud has three other developers who have appeared in the top 10 contributors list over the years. Overall, the current cloud providers like AWS, Alibaba Cloud, Google, and Tencent Cloud have nearly 20 developers actively contributing to the Redis community. The investment of cloud providers in the Redis community is evident and contrasts with the common perception of cloud providers freeloading off the open source community.
Split
Because of the involvement of numerous cloud provider contributors that, following Redis's announcement of the license change, Madelyn Olson from AWS immediately initiated a fork of Redis named Valkey, with plans to host it under the Linux Foundation. Google and Ericsson have already explicitly expressed their support for the development of the Valkey community.
Other cloud provider developers are almost left with no choice but to migrate to the Valkey community, as the new licensing terms for Redis exclude cloud providers, preventing them from continuing to contribute to the Redis community. It appears that Redis has no intention of allowing the community to deeply participate in further development. According to feedback from several Chinese committers, the permissions of the GitHub redis-committers team were revoked within a week, removing the external committers' repository write access and Issue/PR management access. Now, their permissions in the Redis project are essentially the same as those of ordinary users.
"In addition to participating in specific functional contributions to the Redis community, we also contribute back to the community the fixes and improvements in aspects such as functionality, performance, stability, and observability that we have accumulated in our cloud products. The rich user base of our cloud products also conveys a large number of real users' needs to the upstream community. We believe it is our responsibility, and we trust that a thriving open source community is worth our long-term maintenance," said Zhao Zhao of Alibaba Cloud.
From the data, among the top 10 contributors to Redis in 2024, aside from two developers from Redis Inc., the remaining seven have already participated in the development of the Valkey project. This indicates that the Valkey project has effectively become the new community and is now in normal operation, while the developers at Redis Inc. will continue to independently develop and maintain the Redis project.
Data updated in 2024.9
From a macro data perspective, the Redis community has maintained an OpenRank collaboration influence of around 80 in the past six months, while Valkey, just ten days after being open sourced in March, soared to an OpenRank of about 40, reaching half of the Redis project's level. In terms of the number of developers participating in the community, Redis has been maintaining a scale of around 100 people per month. In March, due to the license modification, a significant number of developers were involved in the discussion threads in the Redis community, leading to a doubling of participants to 220 people. Meanwhile, within ten days of Valkey being open sourced, the number of participants reached 146, surpassing the regular scale of Redis.
Overall, the split in the Redis community seems irreversible. With Valkey being donated to the Linux Foundation, it is expected that more open source developers will participate in the contribution and development of Valkey.
Ripples
Just as the underlying value proposition of the OpenRank algorithm suggests, the world is always interconnected and influencing each other; any event will not only affect itself but will ripple through to other related parts. As mentioned in the 2023 China Open Source Annual Report, we discovered through data that in September 2023, Unity's change in pricing strategy directly led to the largest growth spurt since the inception of the open source game engine godotengine. Of the 80,000 stars for this project, which has been open source for over a decade, more than 10,000 stars came from September 2023 alone, as game developers responded to Unity's decision with support for open source.
Apart from giving rise to a new forked community, Valkey, the license change in Redis also led many developers in need of key-value databases to start paying attention to other open source projects related to Redis. Apache Software Foundation's kvrocks is one such project. Unlike Redis, which is an in-memory key-value database, kvrocks is a disk-based key-value database. As seen in the graph below, kvrocks experienced a significant increase in various metrics in March, possibly because it is a foundation-host project. In an era where the enterprises behind open source projects can bypass set community rules and unilaterally change the license at any time, hosting a project with a foundation may provide developers with a greater sense of security.
Close
The practice of cloud providers exploiting open source projects has been a criticism among open source developers in the past few years, but changes are subtly taking place. More cloud providers are recognizing the importance of community and are willing to invest employees and even material resources into the open source communities they depend on, to ensure that their cloud services can develop in better coordination with upstream sources. In the future, we believe that the upstream and downstream of the open source community can collaborate more effectively, creating a win-win situation for all parties involved. Effective contributions and influence evaluation in open source are prerequisites for forming a healthier and more efficient collaborative mechanism, to identify those developers who make genuine contributions, and to ensure that what they create can indeed belong to them.