SAS Redis deployment changes with SAS Viya 2024.12
SAS Redis Server is a SAS Viya platform component based on the open-source Redis project. Redis provides a distributed cache technology to microservices in the SAS Viya platform. SAS Redis was first introduced with the 2022.10 SAS Viya platform release; starting with the 2024.12 release, its architecture has been simplified and the overall resources utilization reduced.
Streamlining the architecture
The SAS Viya platform introduced SAS Redis as a brand-new server component, used to provide distributed caching capabilities, and replacing the previously used SAS Cache Server and SAS Cache Locator. The initial architecture was designed with good engineering principles, including flexibility, scalability and management though a custom-built Kubernetes operator. Real-world experience showed that a more focused approach would better serve the current requirements, aligning with actual usage patterns and maintenance needs, while reducing complexity.
Starting with the 2024.12 release, the following changes have been introduced:
Previously, a SAS Viya platform deployment created a Redis Cluster with 3 Kubernetes Statefulsets, each one including a controller and a replica node. The cluster was described by a custom resource, called “distributedredisclusters.redis.kun.sas-redis-server”, and managed by the SAS Redis operator, which run in a stateless pod.
Now, Redis is still started in cluster mode, but it only has a single Statefulset with two pods: one controller and one replica node. There are no more custom resources to describe it, and it is not managed by the SAS Redis operator anymore.
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Redis pods as seen in OpenLens on a SAS Viya platform release 2024.12
Streamlining the management
You might have noticed that the Redis Operator is still deployed and running in the Kubernetes cluster, yet it’s not managing SAS Redis server anymore. Why is it there? We have decided to keep it to simplify updates from previous releases: as soon as it starts, it will delete any resource that is not required anymore, such as any instance of the “distributedredisclusters.redis.kun” custom resource, or the previously-defined Statefulsets. No need to manually delete any unnecessary Kubernetes objects!
The operator log confirms this at startup, printing this message:
{"level":"info","ts":"2024-12-23T21:05:51Z","logger":"cmd","msg":"The redis operator is now deprecated. Resources previously created by the operator will be removed if they exist."}
Once this is done at the first run, you can scale the operator down and stop it, if you want to. SAS will remove the SAS Redis operator in a subsequent release.
Events that were handled by the operator will now be performed directly by the SAS Redis server pods. As an example, the command to shutdown the Redis server changes from:
kubectl -n name-of-namespace patch distributedredisclusters.redis.kun sas-redis-server --type json --patch '[{"op":"replace", "path": "/spec/shutdown", "value":true}]'
to:
kubectl -n name-of-namespace scale statefulset sas-redis-server --replicas 0
Nothing else has changed. SAS Redis provides the same functionality as before. It has the same requirements: for example, each server pod is configured to request 1 Gi of persistent storage with RWO accessMode. And we still recommend using a block storage device for Redis persistent storage. For more information, see https://go.documentation.sas.com/doc/en/sasadmincdc/default/itopssr/n0ampbltwqgkjkn1j3qogztsbbu0.htm....
Conclusion
SAS Viya, in its continuous evolution, keeps optimizing its components to lower resource consumption and simplify platform management. In this article, we have seen how SAS Redis has changed starting with the 2024.12 release. For more information about the management of SAS Redis Server, consult the updated SAS Viya Administration: Infrastructure Servers page.
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