hashicorp/memberlist
Memberlist
Memberlist is a Go library used for maintaining distributed cluster membership and failure detection via a peer-to-peer gossip protocol. It functions as a cluster state synchronizer, allowing nodes to track active members and propagate metadata without a central coordinator.
The library implements a secure gossip mechanism using AES-GCM encryption to protect inter-node communication and membership data. It distinguishes its failure detection through a suspicion-based model and adaptive timeout scaling, which reduces false positives caused by transient network latency.
The project provides capabilities for broadcasting custom user-defined data, synchronizing node state via push-pull mechanisms, and managing network transport through a decoupled interface. It also includes tools for operational monitoring, such as round-trip time measurement and performance metrics emission.
Features
- Gossip-Based Cluster Membership - Provides a gossip-based protocol to maintain a consistent distributed view of cluster membership.
- Gossip Protocols - Uses a peer-to-peer gossip mechanism to propagate membership updates and custom user data across the cluster.
- Cluster State Synchronization - Synchronizes full membership lists and node state using a TCP-based push-pull reconciliation mechanism.
- Distributed State Synchronization - Synchronizes membership and metadata state across distributed nodes to ensure eventual consistency.
- Node Failure Detection - Identifies unresponsive nodes using heartbeats and broadcasts suspicion messages to maintain membership accuracy.
- Suspicion-Based Failure Detection - Implements a suspicion-based model to reduce false positive node evictions caused by transient network flakiness.
- SWIM Failure Detectors - Implements a distributed failure detector using a gossip-based algorithm to identify unresponsive peers.
- Message Encryption - Secures gossip communication between nodes using encryption to prevent unauthorized reading of cluster data.
- AEAD Encryptions and Decryptions - Uses AES-GCM authenticated encryption to secure membership data and inter-node communication.
- Gossip Packet Authentication - Attaches labels to packets and streams to authenticate data and validate inbound traffic between nodes.
- AES-Encrypted Transports - Secures inter-node gossip communication and membership data using AES-GCM encryption.
- Heartbeat - Monitors remote peer health using lightweight UDP heartbeat pings and round-trip time measurements.
- Cluster Membership Change Notifications - Triggers notifications when nodes join, leave, or update metadata to allow applications to react to state changes.
- Encrypted Gossip Implementations - Implements a secure communication layer using AES-GCM encryption to protect inter-node gossip and membership data.
- Cluster Merge Controls - Evaluates peer lists during join operations to prevent unauthorized cluster unions.
- Node Metadata Management - Associates custom byte-limited metadata with nodes to be synchronized across the cluster membership list.
- Cluster-Wide Broadcasting - Sends state synchronization messages to all discovered nodes using a prioritized queuing mechanism.
- Priority-Based Broadcast Queues - Manages the distribution of cluster-wide messages using queues that prioritize new updates and limit retransmissions.
- Gossip Message Broadcasting - Allows the transmission of arbitrary user-defined data across the gossip network to all cluster members.
- Reliable Byte Stream Implementations - Transmits byte payloads to specific nodes using a variety of delivery guarantees including TCP and UDP.
- Round-Trip Time Measurement - Measures the duration between pings and acknowledgements to estimate network latency between peers.
- Peer-to-Peer Networking Libraries - Provides a library for transport, security, and peer discovery to facilitate decentralized cluster communication.
- Gossip Broadcasts - Propagates user-defined custom data across the cluster using gossip-style broadcasts.
- Transport Abstractions - Decouples gossip logic from the network layer via an interface that abstracts UDP packets and TCP streams.
- Transport Listeners - Creates TCP and UDP listeners on specific addresses and ports to manage connectionless packets and streams.
- Encryption Key Management - Maintains and rotates the shared secret keys used to encrypt and decrypt all cluster communications.
- Peer Communication Security - Secures inter-node communication and gossip data using shared keys and AES-GCM encryption.
- Adaptive Timeouts - Implements dynamic adjustment of failure detection timeouts based on network latency and local health.
- Algorithms - Gossip protocol for cluster membership.
