Inside the migration from Consul to memberlist at Grafana Labs

Grafana Labs transitioned from using Consul to embedded memberlist to manage distributed databases, focusing on improving scalability and reliability. The migration involved configuring a multi-KV store client to initially use both Consul and memberlist, gradually shifting all traffic to memberlist to eliminate Consul as a single point of failure. This change was prompted by limitations in Consul's performance under heavy loads, primarily due to its compare-and-swap operations and additional read requests. By adopting memberlist, which utilizes a gossip protocol, Grafana Labs reduced network traffic and removed the dependency on a dedicated KV store, allowing for more efficient scaling of their components. The migration process included careful management of Kubernetes labels to ensure that memberlist communications were properly segregated across namespaces, preventing cross-namespace interference and potential data loss. This strategic shift not only enhanced the scalability of their production environments but also allowed for more resilient and efficient deployment models. The Grafana Mimir team's contributions were instrumental in developing the internal memberlist libraries and migration steps, which were adapted for use by the Loki team.