etcd is a distributed key value store that provides a reliable way to store data across a cluster of machines with best-of-class stability, reliability, scalability, and performance. The project – frequently teamed with applications such as Kubernetes, M3, Vitess, and Doorman – handles leader elections during network partitions and will tolerate machine failure, including the leader.
“etcd acts as a source of truth for systems like Kubernetes,” said Brian Grant, TOC representative and project sponsor, Principal Engineer at Google, and Kubernetes SIG Architecture Co-Chair and Steering Committee member. “As a critical component of every cluster, having a reliable way to automate its configuration and management is essential. etcd offers the necessary coordination mechanisms for cloud native distributed systems, and is cloud native itself.”
All Kubernetes clusters use etcd as their primary data store. As such, it handles storing and replicating data for Kubernetes cluster state and uses the Raft consensus algorithm to recover from hardware failure and network partitions. In addition to Kubernetes, Cloud Foundry also uses etcd as their distributed key-value store. This means etcd is used in production by companies such as Ancestry, ING, Pearson, Pinterest, The New York Times, Nordstrom, and many more.
“Alibaba uses etcd for several critical infrastructure systems, given its superior capabilities in providing high availability and data reliability,” said Xiang Li, senior staff engineer, Alibaba. “As a maintainer of etcd we see the next phase for etcd to focus on usability and performance. Alibaba looks forward to continuing co-leading the development of etcd and making etcd easier to use and more performant.”
“AWS is proud to have dedicated maintainers of etcd on our team to help ensure the bright future ahead for etcd. We look forward to continuing work alongside the community to continue the project’s stability,” said Deepak Singh, Director of Container Services at AWS.
“The Certificate Transparency team at Google works on both implementations and standards to fundamentally improve the security of internet encryption. The Open Source Trillian project is used by many organizations as part of that effort to detect the mis-issuance of trusted TLS certificates on the open internet”, says Al Cutter, the team lead, “And, etcd continues to play a role in the project by safely storing API quota data to protect Trillian instances from abusive requests, and reliably coordinating critical operations.”
Written in Go, etcd has unrivaled cross-platform support, small binaries, and a thriving contributor community. It also integrates with existing cloud native tooling like Prometheus monitoring, which can track important metrics like latency from the etcd leader and provide alerting and dashboards.
“Kubernetes and many other projects like Cloud Foundry depend on etcd for reliable data storage. We’re excited to have etcd join CNCF as an incubation project and look forward to cultivating its community by improving its technical documentation, governance and more,” said Chris Aniszczyk, COO of CNCF. “etcd is a fantastic addition to our community of projects.”
“When we introduced etcd during the early days of CoreOS, we wanted it to be this ubiquitously available component of a larger system. Part of the way you get ubiquity is to get everyone using it, and etcd hit critical mass with Kubernetes and has extended to many other projects and users since. As etcd goes into the CNCF, maintainers from Amazon, Alibaba, Google Cloud, and Red Hat all have nurtured the project as its user base has grown. In fact, etcd is deployed in every major cloud provider now and is a part of products put forward by all these companies and across the cloud native ecosystem,” said Brandon Philips, CTO of CoreOS at Red Hat. “Having a neutral third party stewarding the copyrights, DNS and other project infrastructure is the reasonable next step for the etcd project and users.”
Other common use cases of etcd include storing important application configuration like database connection details or feature flags as key value pairs. These values can be watched, allowing the application to reconfigure itself when changed. Advanced uses take advantage of the consistency guarantees to implement database leader elections or do distributed locking across a cluster of workers.
Main etcd Features:
- Easily manages cluster coordination and state management across any distributed system
- Written in Go and uses the Raft consensus algorithm to manage a highly available replicated log
- Enables reliable distributed coordination through distributed locking, leader election, and write barriers
- Handles leader elections during network partitions and will tolerate machine failure, including the leader
- Supports dynamic cluster membership reconfiguration
- Offers stable read/write under high load
- Includes a multi-version concurrency control data model
- Empowers reliable key monitoring, which never silently drop events
- Lease primitives for expiring keys
- 469 contributors
- 21,627 GitHub stars
- 157 releases
- 14,825 commits
- 4,310 forks
- 9 maintainers representing 8 companies
As a CNCF hosted project, joining Incubated technologies like OpenTracing, Fluentd, Linkerd, gRPC, CoreDNS, containerd, rkt, CNI, Envoy, Jaeger, Notary, TUF, Vitess, NATS Helm, Rook and Harbor, etcd is part of a neutral foundation aligned with its technical interests, as well as the larger Linux Foundation, which provide governance, marketing support, and community outreach.
Every CNCF project has an associated maturity level: sandbox, incubating, or graduated project. For more information on what qualifies a technology for each level, please visit the CNCF Graduation Criteria v.1.1.