Amazon Q business knowledge share with External application in EC2

Based on the information available, there isn't a direct way to share an Amazon Q Business knowledge base with an external application running on EC2. Amazon Q Business is designed to work within its own ecosystem, with specific access controls and integration methods.

However, you have a few potential options to consider:

1. Custom Plugin Integration: You could set up a custom plugin for Amazon Q Business that interacts with your EC2 application. This would allow your EC2 application to make API calls to Amazon Q Business through the plugin, leveraging the knowledge base you've already created.

2. API Gateway and Amazon Cognito: You could create an integration where your EC2 application authenticates through Amazon Cognito and accesses the Amazon Q Business functionality via API Gateway. This would require setting up the proper authentication and authorization flows.

3. Amazon Q Business Web Experience: If your EC2 application can embed or redirect to web content, you could potentially use the Amazon Q Business web interface URL and handle authentication appropriately.

4. Amazon Q Apps: If you're using the Pro tier, you could create Amazon Q Apps that encapsulate specific functionality from your knowledge base and then find a way to integrate these with your EC2 application.

Each of these approaches would require additional development work and proper authentication/authorization setup. The Amazon Q Business Pro tier offers more integration capabilities than the Lite tier, including custom plugins and integrations with third-party applications.

Note that Amazon Q Business is designed with permissions-aware responses, so any integration would need to respect the access controls you've set up for your knowledge base.
Sources
Set up a custom plugin on Amazon Q Business and authenticate with Amazon Cognito to interact with backend systems | AWS Machine Learning Blog
Amazon Q Business subscription tiers and index types - Amazon Q Business