Port Waiting

/**
 * Waits for a port to become available (occupied by another process)
 * @param port - Port number to wait for
 * @param options - Configuration options for retry behavior
 * @returns Promise that resolves to true when port becomes available, or throws on timeout
 */
function waitPort(port: number, options?: WaitPortOptions): Promise<boolean>;

/**
 * Options for configuring port waiting behavior
 */
interface WaitPortOptions {
  /** Interval between retry attempts in milliseconds (default: 1000) */
  retryInterval?: number;
  /** Maximum number of retry attempts (default: Infinity) */
  retries?: number;
}

import { waitPort } from "detect-port";

// Wait for port 3000 to become available (default options)
try {
  await waitPort(3000);
  console.log("Port 3000 is now available!");
} catch (error) {
  console.error("Failed to wait for port:", error);
}

// Wait with custom retry options
try {
  await waitPort(8080, {
    retryInterval: 500,  // Check every 500ms
    retries: 20         // Give up after 20 attempts (10 seconds)
  });
  console.log("Port 8080 is now available!");
} catch (error) {
  console.error("Timeout waiting for port 8080");
}

// Wait indefinitely with custom interval
await waitPort(9000, {
  retryInterval: 2000  // Check every 2 seconds, retry forever
});

import { waitPort } from "detect-port";
import { spawn } from "child_process";

// Start a server process
const serverProcess = spawn("node", ["server.js"]);

// Wait for the server to be ready
try {
  await waitPort(3000, { retries: 30, retryInterval: 1000 });
  console.log("Server is ready!");
  
  // Now safe to make requests to the server
  // ... your application logic
} catch (error) {
  console.error("Server failed to start within 30 seconds");
  serverProcess.kill();
}

import { waitPort } from "detect-port";

async function setupTestEnvironment() {
  // Start test database
  const dbProcess = startTestDatabase();
  
  // Wait for database to be ready
  await waitPort(5432, { retries: 20, retryInterval: 500 });
  
  // Start application server
  const appProcess = startTestServer();
  
  // Wait for application to be ready
  await waitPort(3000, { retries: 15, retryInterval: 1000 });
  
  console.log("Test environment is ready!");
  return { dbProcess, appProcess };
}

/**
 * Error thrown when waitPort exceeds the maximum number of retry attempts
 */
class WaitPortRetryError extends Error {
  /** Maximum number of retries that were configured */
  retries: number;
  /** Actual number of attempts made (including the first attempt) */
  count: number;
  
  constructor(message: string, retries: number, count: number, options?: ErrorOptions);
}

import { waitPort, WaitPortRetryError } from "detect-port";

try {
  await waitPort(3000, { retries: 5, retryInterval: 1000 });
} catch (error) {
  if (error instanceof WaitPortRetryError) {
    console.error(`Failed to detect port availability after ${error.count} attempts`);
    console.error(`Maximum retries configured: ${error.retries}`);
  } else {
    console.error("Unexpected error:", error);
  }
}