Model Context Protocol (MCP) Gateway Service

This implementation functions as an MCP gateway, mandating prerequisite user authentication. Upon successful identity verification, the gateway gains the necessary delegated authority to invoke restricted backend services on the user's behalf.

Prerequisites and Setup

Dependency: Todos Backend Service

Prior to operationalizing this MCP gateway, the consumer must first deploy the designated Todos API, following the instructions detailed in this documentation.

Auth0 Application Configuration

Within the Auth0 administrative console, provision a new application entity under the Applications grouping (ensure the application type is set to "Regular Web Application").

During local development setup, register the following URI as the designated callback endpoint:

http://localhost:8788/callback

Persistent Key-Value Store Initialization

Execute the following command to establish the required durable storage namespace:

bash wrangler kv:namespace create "OAUTH_KV"

Subsequently, integrate the resulting KV identifier into the project's Wrangler configuration file.

Essential Environment Variables

This MCP Gateway necessitates the configuration of several environment parameters:

Parameter	Specification
AUTH0_DOMAIN	The fully qualified domain name for your Auth0 tenant (e.g., myorg.auth0.com)
AUTH0_CLIENT_ID	The unique Client Identifier obtained from your newly provisioned Auth0 application
AUTH0_CLIENT_SECRET	The confidential Client Secret associated with the Auth0 application instance
AUTH0_AUDIENCE	The designated identifier for the target API, as registered in the Auth0 portal (e.g., api://todos-backend-service)
AUTH0_SCOPE	The set of required permissions, typically including identity claims (openid email profile), token refresh capability (offline_access), and resource access grants (read:todos)
NODE_ENV	Defines the operational mode; use development when running locally
API_BASE_URL	The network address where the protected Todos API is actively hosted

Local Development Environment

Establish a configuration file named .dev.vars in the project root, structuring it as follows:

AUTH0_DOMAIN=yourdomain.us.auth0.com AUTH0_CLIENT_ID=YourAuth0AppClientID AUTH0_CLIENT_SECRET=YourAuth0AppClientSecret AUTH0_AUDIENCE=urn:todos-api AUTH0_SCOPE=openid email profile offline_access read:todos NODE_ENV=development API_BASE_URL=http://localhost:8789

Initiating the Gateway Service

To launch the gateway in development mode, execute:

bash npm run dev

Utilize the MCP Inspector utility to interface with this running service. Configure the transport mechanism to sse and set the service URL to http://localhost:8788/sse to discover and invoke available tools.

Deployment to Cloudflare Workers

To finalize the deployment of the MCP Gateway to the Cloudflare infrastructure, set the following values as environment secrets:

bash wrangler secret put AUTH0_DOMAIN wrangler secret put AUTH0_CLIENT_ID wrangler secret put AUTH0_CLIENT_SECRET wrangler secret put AUTH0_AUDIENCE wrangler secret put AUTH0_SCOPE wrangler secret put API_BASE_URL

After secret provisioning, initiate the deployment sequence:

bash npm run deploy

Crucially, update the Auth0 configuration to include the production Callback URI for the deployed Worker, structured like this:

bash https://mcp-auth0-oidc..workers.dev/callback

Verification can be performed via the Cloudflare Workers AI LLM Playground. Connect to your deployed gateway by specifying the endpoint pattern in the lower-left panel:

https://mcp-auth0-oidc..workers.dev/sse

This action will trigger an authentication prompt, granting access to all associated tools upon successful sign-in.

Debugging and Error Resolution

Should operational difficulties arise during setup or usage, consult these diagnostic paths:

Worker Execution Logs

Reference the Cloudflare Workers Logs interface within your dashboard.

Auth0 Authentication Activity Stream

• Access the Logs area within your Auth0 administrative panel.
• Scrutinize records pertaining to login attempts and authorization failures.

Common Failure Points

• Authentication failures typically point to discrepancies in the Auth0 setup or secret values.
• Connectivity issues often stem from an un-deployed Worker or an incorrect public domain specification.
• Verify that every required callback endpoint has been precisely registered in Auth0.
• Confirm that API_BASE_URL accurately resolves to the running backend service endpoint.

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== History == The concept behind XMLHttpRequest was conceived in 2000 by the developers of Microsoft Outlook. The concept was then implemented within the Internet Explorer 5 browser (1999). However, the original syntax did not use the XMLHttpRequest identifier. Instead, the developers used the identifiers ActiveXObject("Msxml2.XMLHTTP") and ActiveXObject("Microsoft.XMLHTTP"). As of Internet Explorer 7 (2006), all browsers support the XMLHttpRequest identifier. The XMLHttpRequest identifier is now the de facto standard in all the major browsers, including Mozilla's Gecko layout engine (2002), Safari 1.2 (2004) and Opera 8.0 (2005).

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== Usage == Generally, sending a request with XMLHttpRequest has several programming steps.

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== Cross-domain requests ==

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