SERF: In a Nutshell

What is SERF

SERF is open source decentralized, fault-tolerant and highly available solution by Hashicorp used for cluster membership management, failure detection and orchestration.

Serf relies on an efficient and lightweight gossip protocol to communicate with nodes. The Serf agents periodically exchange messages with each other in much the same way that a zombie apocalypse would occur: it starts with one zombie but soon infects everyone. It communicates using both TCP and UDP protocols. It is extremely lightweight and uses low memory footprint(5 to 10 MB). Serf runs on every major platform: Linux, Mac OS X, and Windows.

Serf tries to solves problems related to clustered architectures,

• Cluster Membership Management: Serf maintains list of members present in the cluster. It also provides provision to execute custom handler scripts whenever membership changes. Serf agents exchange messages to each other periodically to check the membership status i.e. joining or leaving of members.
• Failure Detection and Recovery: Serf automatically detects failed nodes within seconds, notifies the rest of the cluster, and executes handler scripts allowing you to handle these events. Serf will attempt to recover failed nodes by reconnecting to them periodically.
• Event Propagation: Serf can broadcast custom events and queries to the cluster. These can be used to trigger deploys, propagate configuration, etc. Events are simply fire-and-forget broadcast, and Serf makes a best effort to deliver messages in the face of offline nodes or network partitions. Queries provide a simple real-time request/response mechanism.

Use Cases

SERF is decentralize solution for cluster management so it solves use-cases that are having decentralized state, masterless architecture, and are completely fault tolerant.

• Webservers and load balancers
• Memcached and Redis clusters
• Triggering deployments
• Updating DNS records
• Simple Observability
• A Building Block for Service Discovery

References

• https://www.serfdom.io
• https://www.serfdom.io/docs/index.html