Function bindProbe

e2e/src/ports.ts:111–122

(port: number)

// microseconds (close, then boot). Services bind 127.0.0.1 or dual-stack `::`,
// both of which succeed once the probes are released.
const bindProbe = async (port: number): Promise<ReadonlyArray<Server> | undefined> => {
  const loopbacks = await Promise.all(["127.0.0.1", "::1"].map((host) => isListening(port, host)));
  if (loopbacks.some(Boolean)) return undefined;
  const v4 = await listenOn({ port, host: "0.0.0.0" });
  if (!v4) return undefined;
  const v6 = await listenOn({ port, host: "::", ipv6Only: true });
  if (!v6) {
    await closeServer(v4);
    return undefined;
  }
  return [v4, v6];
};

export interface PortClaim {
  readonly envVar: string;