Lessons Learned from Building a Database Operator

Another talk as part of the Data On Kubernetes Day.

Baseline

Hosting Models

• Managed: Atlas
• Semi: Cloud manager
• Self-hosted: Enterprise and community operator

MongoDB on K8s

• Cluster Architecture
  • Control Plane: Operator
  • Data Plane: MongoDB Server + Agent (Sidecar Proxy)
• Enterprise Operator
  • OpsManager CR: Deploys 3-node operator DB and OpsManager
  • MongoDB CR: The MongoDB clusters (Compromised of agents)
• Advanced use case: Data Platform with MongoDB on demand
  • Control Plane on one cluster (or on VMs/Bare-metal), data plane in tenant clusters
  • Result: MongoDB CR can not relate to OpsManager CR directly

Pitfalls

• Storage: Agnostic, Topology aware, configurable and resizable (can’t be done with Statefulset)
• Networking: Cluster-internal (Pod to Pod/Service), External (Split horizon over multicluster)