Jihane Lazrag's blog

Copilot’s built-in knowledge is great, but sometimes you need fresh data or to trigger actions in your own systems. In this article, we’ll show you how to combine Retrieval-Augmented Generation (RAG) with a simple FastAPI service as a custom connector—so your Copilot Studio agent can pull live information and carry out real-world tasks.

For example, imagine your agent must query an SAP or Oracle ERP endpoint to fetch up-to-date inventory and pricing. You can wrap those product-list APIs in a FastAPI app and expose it as a connector that your Copilot agent calls at runtime.

Here’s how to put it all in place:

1. FastAPI service deployed in Azure

Assume you’ve taken your FastAPI “product-list” app and deployed it to Azure App Service (or Azure Container Apps), exposing it at https://my-products-api.azurewebsites.net . You can follow this link to have a code sample to build this FastAPI;

2. Create a Custom Connector in Power Apps

1. Go to make.powerapps.com.
2. Go to Custom connectors → New custom connector → Create from blank.
3. General Information:
   • Host: php-templateCopyEdit<your-app>.azurewebsites.net
   • Base URL: leave as / if you don’t have a sub-path.Scheme: Choose HTTPS.
4. Security (Authentication):
   • If your API is open, choose: yamlCopyEditNo authentication
   • If you use an API key or bearer token, configure it here.
   Click Definition.

Step 3: Define your API endpoints manually

Here you manually add each FastAPI route you wish to use.

Example: Fetch Product by ID

• Click New Action:
  • Summary: Get Product by ID
  • Operation ID: GetProductById
  • Visibility: Important

• Scroll down to Request and click + Import from sample:
  • Verb: GET
  • URL: arduinoCopyEdithttps://<your-app>.azurewebsites.net/products/{product_id}
  • Click Import.
    This automatically recognizes the parameter {product_id}.
• Ensure the parameter is correctly recognized:
  • Click on product_id parameter to set its type (e.g., integer or string).

Step 4: Define the Response Manually

Under Response, click + Add default response:

• Paste a valid JSON example response from your API. For example: jsonCopyEdit{ "id": 2, "name": "Gadget", "price": 29.99, "description": "An advanced gadget with lots of features." }
• Click Import.

This auto-generates the response schema.

Step 5: Test your Connector

1. Go to the Test tab.
2. Click Create connector first, then refresh the page if required.
3. Enter a valid product ID and test it:
   • Example: 2
   • Click Test Operation.

You should see your FastAPI response returned successfully.

3.Add your connector as a Copilot Studio skill

Configure Agent Behavior to call your Custom Connector

• In the agent’s System prompt, clearly instruct your agent how and when to use your connector. For example:

When the user asks about a specific product by ID, call the ProductAPI connector using the "GetProductById" action, passing the specified ID as parameter. Format the response nicely as follows:

Product Name: [name]  
Price: $[price]  
Description: [description]