decouple config validation from connection

Author: blva

src/helpers/connectionOptions.ts

@@ -40,3 +40,18 @@ export async function setAppNameParamIfMissing({
 
     return connectionStringUrl.toString();
 }
+
+/**
+ * Validates the connection string
+ * @param connectionString - The connection string to validate
+ * @param looseValidation - Whether to allow loose validation
+ * @returns void
+ * @throws Error if the connection string is invalid
+ */
+export async function validateConnectionString(connectionString: string, looseValidation: boolean): Promise<void> {
+    try {
+        new ConnectionString(connectionString, { looseValidation });
+    } catch (error) {
+        throw new Error(`Invalid connection string with error: ${error}`);
+    }
+}

src/server.ts

@@ -9,6 +9,7 @@ import { Telemetry } from "./telemetry/telemetry.js";
 import { UserConfig } from "./common/config.js";
 import { type ServerEvent } from "./telemetry/types.js";
 import { type ServerCommand } from "./telemetry/types.js";
+import ConnectionString from "mongodb-connection-string-url";
 import {
     CallToolRequestSchema,
     CallToolResult,
@@ -17,6 +18,7 @@ import {
 } from "@modelcontextprotocol/sdk/types.js";
 import assert from "assert";
 import { ToolBase } from "./tools/tool.js";
+import { validateConnectionString } from "./helpers/connectionOptions.js";
 
 export interface ServerOptions {
     session: Session;
@@ -106,6 +108,9 @@ export class Server {
             });
 
             this.emitServerEvent("start", Date.now() - this.startTime);
+
+            // Placed here to start the connection to the config connection string as soon as the server is initialized.
+            this.connectToConfigConnectionString();
         };
 
         this.mcpServer.server.onclose = (): void => {
@@ -188,20 +193,17 @@ export class Server {
     }
 
     private async validateConfig(): Promise<void> {
+        // Validate connection string
         if (this.userConfig.connectionString) {
             try {
-                await this.session.connectToMongoDB({
-                    connectionString: this.userConfig.connectionString,
-                });
+                await validateConnectionString(this.userConfig.connectionString, false);
             } catch (error) {
-                console.error(
-                    "Failed to connect to MongoDB instance using the connection string from the config: ",
-                    error
-                );
-                throw new Error("Failed to connect to MongoDB instance using the connection string from the config");
+                console.error("Connection string validation failed with error: ", error);
+                throw new Error("Connection string validation failed with error: " + error);
             }
         }
 
+        // Validate API client credentials
         if (this.userConfig.apiClientId && this.userConfig.apiClientSecret) {
             try {
                 await this.session.apiClient.validateAccessToken();
@@ -219,4 +221,20 @@ export class Server {
             }
         }
     }
+
+    private async connectToConfigConnectionString(): Promise<void> {
+        if (this.userConfig.connectionString) {
+            try {
+                await this.session.connectToMongoDB({
+                    connectionString: this.userConfig.connectionString,
+                });
+            } catch (error) {
+                console.error(
+                    "Failed to connect to MongoDB instance using the connection string from the config: ",
+                    error
+                );
+                throw new Error("Failed to connect to MongoDB instance using the connection string from the config");
+            }
+        }
+    }
 }