ddrinka · January 5, 2018 14:45 · Jan 5, 2018
diff --git a/ProxyPathMiddleware.cs b/ProxyPathMiddleware.cs
@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+using Amazon.Lambda.APIGatewayEvents;
+using Amazon.Lambda.AspNetCoreServer;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+
+namespace WebApi
+{
+	public class ProxyPathMiddleware
+	{
+		readonly RequestDelegate _next;
+		readonly ILogger _logger;
+
+		public ProxyPathMiddleware(RequestDelegate next, ILoggerFactory loggerFactory)
+		{
+			_next = next;
+			_logger = loggerFactory.CreateLogger<ProxyPathMiddleware>();
+		}
+
+		public Task Invoke(HttpContext context)
+		{
+			if (!context.Items.TryGetValue(APIGatewayProxyFunction.APIGATEWAY_REQUEST, out var apiGatewayRequestObject))
+				return _next(context);      //This was not an API Gateway request. Move on.
+
+			var apiGatewayRequest = apiGatewayRequestObject as APIGatewayProxyRequest;
+			if (apiGatewayRequest == null)
+				throw new InvalidOperationException("An API Gateway Request was set but was an invalid type");
+
+			if (apiGatewayRequest.PathParameters == null || !apiGatewayRequest.PathParameters.TryGetValue("proxy", out var proxyPath))
+				return _next(context);      //This was an API Gateway request but was not proxied. Move on.
+
+			var newPath = WebUtility.UrlDecode("/" + proxyPath);
+			_logger.LogDebug($"Rewriting request path. Original={context.Request.Path} New={newPath}");
+
+			context.Request.Path = newPath;
+			return _next(context);
+		}
+	}
+
+	public static class ProxyPathMiddlewareExtensions
+	{
+		public static IApplicationBuilder UseProxyPath(this IApplicationBuilder builder)
+		{
+			return builder.UseMiddleware<ProxyPathMiddleware>();
+		}
+	}
+}