etcd-io/etcd

etcd is a distributed reliable key-value store designed for the most critical data of a distributed system.

etcd solves the problem of maintaining consistent, highly-available state across multiple machines in a distributed system. It uses the Raft consensus algorithm to manage a replicated log, ensuring that data remains reliable even when nodes fail or become unreachable. The tool provides a simple gRPC API, automatic TLS encryption with optional client certificate authentication, and is benchmarked to handle ten thousand writes per second. Its design prioritizes both correctness and performance in scenarios where data loss or inconsistency would be catastrophic.

The tool suits projects that need a central source of truth for critical configuration, service discovery, or coordination data in distributed environments. It is particularly well-matched to infrastructure and cloud-native applications, and has seen production adoption across many companies. Teams should choose etcd when they require strong consistency guarantees and are willing to operate a clustered system; it is not appropriate for use cases where eventual consistency is acceptable or where operational complexity must be minimized. The project includes etcdctl, a command-line client for interacting with the store.

The project receives issue reports from both core maintainers and external users, indicating real-world adoption without an overwhelming support burden. Maintainers typically respond to new issues and pull requests within a day. Work in the issue tracker centers on feature development, bug fixes, and robustness testing, reflecting a focus on expanding capabilities while ensuring reliability through rigorous testing practices.