commit e5155a76e147b37d8d3d7181ad6f94262d165055
Author: Ruchi  Vishwakarma <ruchivishwakarma@fynd-external.com>
Date:   Tue Jul 1 07:17:47 2025 +0000

    code update recorded at: 01/07/25 07:17:47

diff --git a/handler.js b/handler.js
new file mode 100644
index 0000000..2b28679
--- /dev/null
+++ b/handler.js
@@ -0,0 +1,257 @@
+import { MongoClient, ObjectId } from 'mongodb';
+import { createTunnel } from 'tunnel-ssh';
+
+// Maximum allowed connections in the connection pool
+const MAX_CONNECTIONS = parseInt(process.env.MAX_CONNECTIONS) || 10;
+// Connection pool to manage database connections
+const connectionPool = new Map();
+// Timeout for connections, configurable via environment variables
+const CONNECTION_TIMEOUT = parseInt(process.env.CONNECTION_TIMEOUT) || 10000;
+// Maximum limit for query results to prevent large responses
+const MAX_QUERY_LIMIT = parseInt(process.env.MAX_QUERY_LIMIT) || 1000;
+
+/**
+ * Validates the request body for required fields and structure.
+ * Ensures all necessary fields for MongoDB and SSH configurations are provided.
+ * @param {Object} body - Request body containing query and secretData.
+ * @throws {Error} If validation fails.
+ */
+const validateRequestBody = ({ query, secretData }) => {
+  const errors = [];
+
+  // Ensure the query string is provided
+  if (!query) {
+    errors.push('Query is required.');
+  }
+
+  // Validate database configuration
+  const { db_config, ssh_config, use_ssh } = secretData || {};
+  if (!db_config) {
+    errors.push('secretData.db_config is required.');
+  }
+
+  const { hosts, auth_db, database, username, password } = db_config || {};
+  if (!hosts || hosts.length === 0) errors.push('db_config.hosts is required.');
+  if (!auth_db) errors.push('db_config.auth_db is required.');
+  if (!database) errors.push('db_config.database is required.');
+  if (!username) errors.push('db_config.username is required.');
+  if (!password) errors.push('db_config.password is required.');
+
+  // Validate SSH configuration if required
+  if (use_ssh) {
+    if (!ssh_config) {
+      errors.push('secretData.ssh_config is required when use_ssh is true.');
+    } else {
+      const { host, port, username, private_key_file, auth_method } = ssh_config || {};
+      if (!host) errors.push('ssh_config.host is required.');
+      if (!port) errors.push('ssh_config.port is required.');
+      if (!username) errors.push('ssh_config.username is required.');
+      if (auth_method === 'private_key' && !private_key_file) {
+        errors.push('ssh_config.private_key_file is required for private_key auth.');
+      }
+    }
+  }
+
+  // Throw error if any validation fails
+  if (errors.length) {
+    var msg = `Validation errors: ${errors.join(' ')}`
+    console.log(msg)
+    throw new Error(msg);
+  }
+};
+
+/**
+ * Creates a MongoDB connection with a timeout for connection attempts.
+ * Handles connection strings for both direct and SRV-based connections.
+ * @param {Object} config - Configuration for MongoDB.
+ * @param {number} [localPort=null] - Local port for SSH tunneling.
+ * @returns {Promise<Object>} The MongoDB database instance.
+ */
+const createMongoConnection = async (config, localPort = null) => {
+  const { use_ssh } = config.secretData;
+  const { username, password, auth_db, database, hosts, read_preference = 'secondaryPreferred', is_srv } = config.secretData.db_config;
+
+  const host = use_ssh ? '127.0.0.1' : hosts[0]?.host;
+  const port = use_ssh ? localPort : hosts[0]?.port || 27017;
+  const connectionString = is_srv
+    ? `mongodb+srv://${username}:${encodeURIComponent(password)}@${host}/${auth_db}?directConnection=true&readPreference=${read_preference}`
+    : `mongodb://${username}:${encodeURIComponent(password)}@${host}:${port}/${auth_db}?directConnection=true&readPreference=${read_preference}`;
+
+  console.log(`Connecting to MongoDB URI: ${connectionString.replace(username, "<REDACTED>").replace(encodeURIComponent(password), "<REDACTED>")}`);
+
+  // MongoDB client instance
+  const client = new MongoClient(connectionString, { serverSelectionTimeoutMS: CONNECTION_TIMEOUT });
+
+  try {
+    // Attempt to connect to MongoDB within the defined timeout
+    await client.connect();
+    console.log('MongoDB connection successful.');
+    return client.db(database);
+  } catch (error) {
+    console.error(`MongoDB connection failed: ${error.message}`);
+    throw error;
+  }
+};
+
+/**
+ * Establishes an SSH tunnel for secure database connections.
+ * Provides port forwarding from a local port to the remote database server.
+ * @param {Object} sshConfig - SSH configuration.
+ * @param {string} dbHost - Database host.
+ * @param {number} dbPort - Database port.
+ * @returns {Promise<Object>} The SSH tunnel and local port.
+ */
+const createSSHTunnel = async (sshConfig, dbHost, dbPort) => {
+  try {
+    const { host, port, username, private_key_file, auth_method } = sshConfig;
+    const tunnelOptions = { autoClose: true };
+    const forwardOptions = { dstAddr: dbHost, dstPort: dbPort };
+    const sshOptions = {
+      host,
+      port,
+      username,
+      privateKey: auth_method === 'private_key' ? Buffer.from(private_key_file, 'utf-8') : undefined,
+    };
+
+    const [server, conn] = await createTunnel(tunnelOptions, null, sshOptions, forwardOptions);
+    const localPort = server.address().port;
+    console.log(`SSH tunnel established. Local port: ${localPort}`);
+
+    // Attach error listeners to the SSH server and connection
+    server.on('error', (err) => {
+      throw new Error(`SSH Tunnel Server Error: ${err.message}`);
+    });
+    conn.on('error', (err) => {
+      throw new Error(`SSH Tunnel Connection Error: ${err.message}`);
+    });
+
+    return { tunnel: server, localPort };
+  } catch (err) {
+    console.error(`Failed to establish SSH tunnel: ${err.message}`);
+    throw err;
+  }
+};
+
+/**
+ * Retrieves an existing connection or creates a new one if not available.
+ * Ensures that the number of active connections does not exceed the allowed limit.
+ * @param {Object} config - Configuration for the connection.
+ * @param {string} query - MongoDB query to execute.
+ * @returns {Promise<Object>} The MongoDB database instance.
+ */
+const getOrCreateConnection = async (config, query) => {
+  const configKey = JSON.stringify(config);
+
+  // Return existing connection if available
+  if (connectionPool.has(configKey)) {
+    return connectionPool.get(configKey);
+  }
+
+  // Check if connection pool has reached its limit
+  if (connectionPool.size >= MAX_CONNECTIONS) {
+    throw new Error('Connection limit reached.');
+  }
+
+  const { use_ssh, db_config, ssh_config } = config.secretData;
+
+  try {
+    // Create a new connection, either with or without SSH
+    const connection = use_ssh
+      ? await (async () => {
+        const { host: dbHost, port: dbPort } = db_config.hosts[0];
+        const { tunnel, localPort } = await createSSHTunnel(ssh_config, dbHost, dbPort);
+        const mongoConnection = await createMongoConnection(config, localPort);
+        mongoConnection._tunnel = tunnel; // Store tunnel instance for cleanup
+        return mongoConnection;
+      })()
+      : await createMongoConnection(config);
+
+    // Cache the newly created connection
+    connectionPool.set(configKey, connection);
+    return connection;
+  } catch (error) {
+    console.error('Error creating connection:', error.message);
+    throw error;
+  }
+};
+
+/**
+ * Executes a MongoDB query on the provided connection.
+ * Transforms the query string to use the MongoDB collection method if necessary.
+ * Handles different types of MongoDB operations and returns the result.
+ *
+ * @param {string} query - The MongoDB query string to execute.
+ * @param {Object} connection - The MongoDB connection object.
+ * @param {number} [limit=100] - The maximum number of documents to return for queries that return a cursor.
+ * @returns {Promise<Array|Object>} The result of the query execution. For queries that return a cursor, returns an array of documents. For other operations, returns the result object.
+ * @throws {Error} If the query is invalid or if an error occurs during query execution.
+ */
+const runQuery = async (query, connection, limit = 100) => {
+  if (query && typeof query === 'string') {
+    if (query.startsWith('db.') && !query.includes('collection')) {
+      // Extract collection name and method name
+      const parts = query.split('.').slice(1); // Extract parts after 'db.'
+
+      if (parts.length >= 2) {
+        const collectionPart = parts[0]; // The collection name
+        const methodWithParams = parts.slice(1).join('.'); // The rest, which includes method and params
+
+        // Transform query to `db.collection('collectionPart').methodWithParams`
+        query = `db.collection('${collectionPart}').${methodWithParams}`;
+      }
+    }
+
+    console.log('Executing query:', JSON.stringify(query));
+    try {
+      const executeCommand = new Function('db', 'ObjectId', `return ${query.replace(/ObjectId\(/g, 'new ObjectId(')}`);
+      // Pass `ObjectId` from the `mongodb` library to the function
+      const result = await executeCommand(connection, ObjectId);
+      // Handle result based on query type
+      if (result && typeof result.toArray === 'function') {
+        // For queries that return a cursor (e.g., find)
+        console.log(`Limiting to only ${limit} results`)
+        return result.toArray().then((data) => data.slice(0, limit));
+      } else {
+        // For other operations (e.g., countDocuments, aggregate, insert, update)
+        return result || [];
+      }
+    } catch (error) {
+      console.error('Error executing query:', error.message);
+      throw error;
+    }
+  } else {
+    throw new Error("Invalid query", query);
+  }
+};
+
+/**
+ * Express.js handler for incoming requests.
+ * Processes MongoDB queries based on provided configurations and query string.
+ * @param {Object} req - Express request object.
+ * @param {Object} res - Express response object.
+ */
+export const handler = async (req, res) => {
+  try {
+    // Ensure the request method is POST
+    if (req.method !== 'POST') {
+      return res.status(400).json({ error: 'Invalid method, only POST allowed.' });
+    }
+
+    // Extract and validate request body
+    const body = req.body;
+    validateRequestBody(body);
+
+    const { query, secretData } = body;
+    const db = await getOrCreateConnection({ secretData }, query);
+
+    // Execute the provided query in the MongoDB instance
+    const result = await runQuery(query, db, MAX_QUERY_LIMIT);
+
+    console.log('Query executed successfully:', JSON.stringify(result));
+    res.setHeader('Content-Type', 'application/json');
+    res.status(200).json(result);
+  } catch (error) {
+    console.error('Error handling request:', error.message);
+    res.status(500).json({ error: error.message });
+  }
+};
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..5bcb1bb
--- /dev/null
+++ b/package.json
@@ -0,0 +1,19 @@
+{
+    "name": "boltic-mongodb-connector",
+    "version": "1.0.0",
+    "description": "The MongoDB connector enables seamless integration with any MongoDB database, allowing you to perform various operations efficiently.",
+    "main": "handler.js",
+    "scripts": {
+        "start": "node handler.js"
+    },
+    "dependencies": {
+        "mongodb": "^5.0.0",
+        "tunnel-ssh": "^5.1.2"
+    },
+    "engines": {
+        "node": ">=16.0.0"
+    },
+    "author": "Boltic",
+    "license": "MIT",
+    "type": "module"
+}
\ No newline at end of file