/**
 * ALB ↔ Node HTTP keep-alive contract.
 *
 * An ALB holds idle keep-alive connections to its targets open for up to its
 * idle timeout and freely reuses them. Node's default `server.keepAliveTimeout`
 * is 5 seconds — far below the ALB's 60 — so the ALB routinely reuses a
 * connection at the instant Node closes it, surfacing as intermittent
 * ALB-generated 502s that never reach the application. The fix is server-side:
 * the target's keep-alive timeout must exceed the ALB idle timeout, and
 * `headersTimeout` must exceed `keepAliveTimeout` so a request that starts
 * arriving just before the keep-alive deadline is not truncated mid-headers.
 *
 * The Fjall ECS construct pins the ALB idle timeout to
 * `DEFAULT_ALB_IDLE_TIMEOUT_SECONDS` and injects that value into ALB-fronted
 * containers as `FJALL_ALB_IDLE_TIMEOUT_SECONDS` (see
 * `components/infrastructure/lib/resources/aws/compute/applicationLoadBalancer.ts`).
 * This module is the consuming half of the contract: call
 * `applyAlbKeepAliveTimeouts(server)` after `listen()`. When the env var is
 * absent (local dev, containers deployed before the construct injected it) the
 * AWS default of 60 seconds is assumed, which yields the same timeouts.
 */
export declare const FJALL_ALB_IDLE_TIMEOUT_ENV_VAR = "FJALL_ALB_IDLE_TIMEOUT_SECONDS";
/**
 * The ALB idle timeout every Fjall ALB is pinned to (also the AWS default,
 * assumed when the env var is absent). The construct imports this constant so
 * the ALB attribute, the injected env var, and this fallback cannot drift.
 */
export declare const DEFAULT_ALB_IDLE_TIMEOUT_SECONDS = 60;
export interface AlbKeepAliveTimeouts {
    albIdleTimeoutSeconds: number;
    keepAliveTimeoutMs: number;
    headersTimeoutMs: number;
}
/** Structural subset of `node:http.Server` this module tunes. */
export interface KeepAliveTunableServer {
    keepAliveTimeout: number;
    headersTimeout: number;
}
/**
 * Resolves the keep-alive timeouts for a server behind a Fjall ALB from
 * `FJALL_ALB_IDLE_TIMEOUT_SECONDS`. Throws on a malformed value — a
 * misconfigured contract must fail the boot loudly, not race the ALB.
 */
export declare function resolveAlbKeepAliveTimeouts(env?: Record<string, string | undefined>): AlbKeepAliveTimeouts;
/**
 * Applies the resolved timeouts to a Node HTTP(S) server and returns them so
 * the caller can log what was applied.
 */
export declare function applyAlbKeepAliveTimeouts(server: KeepAliveTunableServer, env?: Record<string, string | undefined>): AlbKeepAliveTimeouts;