In this presentation, we explore the concept of knowledge databases, which represent entities and their relationships in a structured and semantic way. By combining this model with immutability—where data is never overwritten, only accumulated—it becomes possible to build systems with a complete, auditable history and native versioning. This approach is particularly powerful in complex ecosystems like Nubank’s, where thousands of microservices interact. We’ll show how modeling these interactions as a knowledge database allows us to uncover patterns, dependencies, and insights that are otherwise hidden, ultimately helping teams understand and evolve the system more safely and intelligently.
Biography
Darlei Soares and João Nascimento are software engineers and data enthusiasts with deep experience in building systems around immutable knowledge databases. Currently part of the engineering team at Nubank, Darlei and João both work on designing and maintaining highly distributed services that leverage Datomic at scale, powering financial operations for millions of customers.
Recorded Nov 13, 2025 at Clojure/Conj 2025 in Charlotte, NC.
Kubernetes installations can be complex with multiple runtime dependencies and runtime engines. CRI-O was created to provide a lightweight runtime for Kubernetes which adds an abstraction layer between the cluster and the runtime that allows for various OCI runtime technologies. However you still have the problem of daemon dependencies in your cluster for builds - I.e. if you are using the cluster for builds you still need a Docker daemon.
Enter Buildah. Buildah allows you to have a Kubernetes cluster without any Docker daemon for both runtime and builds. Excellent. But what if things go wrong? What if you want to do troubleshooting or debugging of containers in your cluster? Buildah isn’t really built for that, what you need is a client tool for working with containers and the one that comes to mind is Docker CLI - but then you’re back to using the daemon.
