What is an Envoy cluster?

A cluster in Envoy refers to a group of logically related endpoints for handling requests. In the context of Envoy, clusters are integral to its architecture, allowing for load balancing and distributing incoming requests across multiple instances of services that share a similar role or function.

When Envoy receives HTTP requests, it needs to determine where to send those requests for processing. The cluster serves as a configuration for identifying a group of upstream endpoints made up of one or more targets that can provide the service. This grouping allows for efficient distribution of traffic and enhances redundancy, as requests can be load-balanced among multiple endpoints within that cluster.

The choice that suggests a type of server configuration does not capture the essence of what a cluster means, as it specifically revolves around the functionalities and organization of multiple endpoints rather than solely focusing on server settings. A single instance of a network service describes a different concept, as it indicates an individual service rather than a collection of endpoints that provide service capabilities. Finally, a method for managing user sessions does not relate to the operational bandwidth of how requests are handled by service clusters in Envoy's architecture.

Thus, the definition of a cluster captures the primary role and function of this feature within Envoy and highlights its importance in service architecture and traffic