Perbackend

Perbackend is a routing concept in distributed systems where requests are directed to distinct backend services based on criteria that identify the target backend rather than sending all traffic to a single pool. The idea supplements traditional pool-based load balancing by maintaining separate backend servers, services, or clusters, allowing deployments to scale and isolate responsibilities more precisely.

In practice, perbackend routing is implemented by reverse proxies, API gateways, or service meshes that support per-backend routing rules. Routes may be defined by host or path, tenant identifier, user or client identity, authentication claims, headers, or query parameters. When a request matches a rule, the gateway forwards it to the corresponding backend and applies backend-specific policies such as timeouts, retries, or circuit breaking.

Common patterns include multi-tenant backends where each tenant has a dedicated service, feature-flag or A/B testing setups with separate backends, and data-plane separation where backends enforce different security or compliance controls. Tools like Envoy, Traefik, and Nginx can implement perbackend routing through configuration of clusters, services, or route tables.

Benefits include improved isolation, targeted scaling, and clearer boundaries between services. Drawbacks include added configuration complexity, potential for uneven load distribution if routing rules are not carefully managed, and the need for consistent monitoring across backends.

See also: load balancing, API gateway, reverse proxy, service mesh, routing policy.