Azure Web Application Custom URL Routing with Azure Functions Proxy
Designed and implemented a custom domain access solution for Azure-hosted web applications using Azure DNS, Function Apps, and reverse proxy routing.
Implemented: November 2023
Problem
The organization required users to access Azure-hosted services through branded custom URLs instead of default Azure endpoints. The solution needed to support secure HTTPS access, centralized DNS resolution, and flexible request routing to multiple Azure web applications while maintaining a clean user experience.
Solution
Implemented a custom URL routing architecture using Azure DNS and Azure Function Apps acting as a lightweight reverse proxy layer.
A custom subdomain was configured within the domain hosting provider and mapped to Azure through CNAME records. Azure Function App Proxy functionality was then used to intercept incoming requests and redirect traffic dynamically to the appropriate Azure-hosted application endpoint.
The implementation allowed centralized control of routing logic while abstracting underlying Azure service URLs from end users.
Architecture
- Users access the application through a branded HTTPS custom URL.
- DNS requests are resolved via the organization’s domain hosting provider.
- A CNAME record maps the custom domain to the Azure Function App endpoint (*.azurewebsites.net).
- Azure Function App Proxy receives and processes inbound requests.
- A .NET-based routing script forwards traffic to the target Azure web application or service endpoint.
Tech Stack
Microsoft Azure • Azure Function Apps • Azure DNS • Azure App Service • .NET • HTTPS • DNS CNAME Records
Outcome
The solution provided a secure and scalable method for exposing Azure services through organization-branded URLs while simplifying endpoint management.
It improved usability for end users, centralized traffic routing, and created a reusable pattern for onboarding additional Azure-hosted applications behind custom domains.
Key Takeaways
- Designed DNS-based request routing for Azure-hosted applications using custom domains.
- Leveraged Azure Function App Proxy to abstract backend service endpoints from users.
- Improved HTTPS accessibility and centralized URL management across Azure services.
- Future iterations could introduce Azure Front Door or Application Gateway for advanced load balancing and WAF capabilities.
Reflection
Future enhancements would include integrating Web Application Firewall (WAF) protection, automated certificate lifecycle management, and migrating routing logic toward Azure Front Door for improved global scalability and resilience.