feat: fail fast when database connection cannot be established

src/hooks.server.ts

@@ -1,8 +1,30 @@
 // src/hooks.server.ts
 import type { Handle } from '@sveltejs/kit';
 import { generateUserId } from '$lib/generateUserId.js';
+import { ensureDatabaseConnection } from '$lib/database/healthCheck';
+
+// Global flag to track if database health check has been performed
+let dbHealthCheckPerformed = false;
 
 export const handle: Handle = async ({ event, resolve }) => {
+	// Perform database health check only once during application startup
+	if (!dbHealthCheckPerformed) {
+		try {
+			await ensureDatabaseConnection({
+				maxRetries: 3,
+				baseDelay: 1000,
+				maxDelay: 10000,
+				timeout: 5000
+			});
+			dbHealthCheckPerformed = true;
+		} catch (error) {
+			console.error('Database health check failed:', error);
+			// The ensureDatabaseConnection function will exit the process
+			// if the database is unavailable, so this catch is just for safety
+			process.exit(1);
+		}
+	}
+
 	const cactoideUserId = event.cookies.get('cactoideUserId');
 	const userId = generateUserId();
 

src/lib/database/healthCheck.ts

@@ -0,0 +1,104 @@
+import postgres from 'postgres';
+import { env } from '$env/dynamic/private';
+
+interface HealthCheckOptions {
+	maxRetries?: number;
+	baseDelay?: number;
+	maxDelay?: number;
+	timeout?: number;
+}
+
+interface HealthCheckResult {
+	success: boolean;
+	error?: string;
+	attempts: number;
+	duration?: number;
+}
+
+/**
+ * Performs a database health check with retry logic and exponential backoff
+ */
+export async function checkDatabaseHealth(
+	options: HealthCheckOptions = {}
+): Promise<HealthCheckResult> {
+	const {
+		maxRetries = 3,
+		baseDelay = 1000, // 1 second
+		maxDelay = 10000, // 10 seconds
+		timeout = 5000 // 5 seconds
+	} = options;
+
+	if (!env.DATABASE_URL) {
+		console.error('DATABASE_URL environment variable is not set');
+		return {
+			success: false,
+			error: 'DATABASE_URL environment variable is not set',
+			attempts: 0
+		};
+	}
+
+	let lastError: Error | null = null;
+
+	console.log(`Starting database health check (max retries: ${maxRetries})`);
+
+	for (let attempt = 1; attempt <= maxRetries; attempt++) {
+		console.log(`Attempt ${attempt}/${maxRetries} - Testing database connection`);
+
+		try {
+			// Create a new connection for the health check
+			const client = postgres(env.DATABASE_URL, {
+				max: 1,
+				idle_timeout: 20,
+				connect_timeout: timeout / 1000, // Convert to seconds
+				onnotice: () => {} // Suppress notices
+			});
+
+			// Test the connection with a simple query
+			await client`SELECT 1 as health_check`;
+			await client.end();
+
+			console.log(`Database connection successful on attempt ${attempt}.`);
+
+			return {
+				success: true,
+				attempts: attempt
+			};
+		} catch (error) {
+			lastError = error as Error;
+			const errorMessage = error instanceof Error ? error.message : 'Unknown error';
+			console.error(`Connection failed on attempt ${attempt}: ${errorMessage}`);
+
+			// Don't wait after the last attempt
+			if (attempt < maxRetries) {
+				const delay = Math.min(baseDelay * Math.pow(2, attempt - 1), maxDelay);
+				console.log(`Waiting ${delay}ms before retry...`);
+				await new Promise((resolve) => setTimeout(resolve, delay));
+			}
+		}
+	}
+
+	const finalError = lastError?.message || 'Unknown database connection error';
+
+	console.error(`All ${maxRetries} attempts failed. Final error: ${finalError}`);
+
+	return {
+		success: false,
+		error: finalError,
+		attempts: maxRetries
+	};
+}
+
+/**
+ * Runs database health check and exits the process if it fails
+ */
+export async function ensureDatabaseConnection(options?: HealthCheckOptions): Promise<void> {
+	const result = await checkDatabaseHealth(options);
+
+	if (!result.success) {
+		console.error('Database connection failed after all retry attempts');
+		console.error(`Error: ${result.error}`);
+		console.error(`Attempts made: ${result.attempts}`);
+		console.error('Exiting application...');
+		process.exit(1);
+	}
+}