backends.http.server-selection

server_selection

Selects a named HTTP server for each request. Configure this statement inside an http backend with server blocks.

See Backend Load Balancing for available policies, the default, and selection behavior.

HTTP servers use name order for fallback. least_connections compares in-flight requests, including requests waiting for retries. Connection limits and health monitoring apply to the backend as a whole.

Transport errors and request timeouts try another server, except with no_fallback. Completed HTTP responses use the shared response mappings and return their normal AAA outcome. HTTP status codes do not trigger failover.

The retry policy applies to the selected server before failover. The backend action timeout covers the complete operation, including retries and failover.

http "HTTP_RADIATORS" {
    server_selection round_robin;
    server "BACKEND_A" { url "http://127.0.0.1:19240"; }
    server "BACKEND_B" { url "http://127.0.0.1:19241"; }

    get "LOOKUP" {
        path "/users/%{aaa.identity}";
    }
}