Allow for headers to be included when the gateway is requesting downs…

…tream swagger endpoint (#39)

* allow for headers to be included when the gateway is requesting downstream swagger endpoint

* refactor and documentation

README.md

@@ -96,6 +96,15 @@ Direct via `http://ocelotprojecturl:port/swagger` provides documentation for dow
                 opt.PathToSwaggerGenerator = "/swagger/docs";
             })
    ```
+   You can optionally include headers that your Ocelot Gateway will send when requesting a swagger endpoint. This can be especially useful if your downstream microservices require contents from a header to authenticate.
+   ```CSharp
+        app.UseSwaggerForOcelotUI(Configuration, opt => {
+            opts.DownstreamSwaggerHeaders = new[]
+              {
+                  new KeyValuePair<string, string>("Auth-Key", "AuthValue"),
+              };
+        })
+   ```
 6. Show your microservices interactive documentation.
    > `http://ocelotserviceurl/swagger`
 

demo/ApiGateway/Startup.cs

@@ -1,4 +1,5 @@
-using Microsoft.AspNetCore.Builder;
+using System.Collections.Generic;
+using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Configuration;
@@ -38,7 +39,14 @@ public void Configure(IApplicationBuilder app, IHostingEnvironment env)
             }
 
             app.UseStaticFiles();
-            app.UseSwaggerForOcelotUI(Configuration)
+            app.UseSwaggerForOcelotUI(Configuration,  opt =>
+                {
+                    opt.DownstreamSwaggerHeaders = new[]
+                    {
+                        new KeyValuePair<string, string>("Key", "Value"),
+                        new KeyValuePair<string, string>("Key2", "Value2"),
+                    };
+                })
                 .UseOcelot()
                 .Wait();
         }

src/MMLib.SwaggerForOcelot/Configuration/SwaggerForOcelotUIOptions.cs

@@ -1,5 +1,6 @@
 using Swashbuckle.AspNetCore.SwaggerUI;
 using System;
+using System.Collections.Generic;
 
 namespace MMLib.SwaggerForOcelot.Configuration
 {
@@ -32,5 +33,10 @@ public string PathToSwaggerGenerator
         /// <see cref="EndPointBasePath"/> + <see cref="SwaggerEndPointConfig.Version"/> + <see cref="SwaggerEndPointOptions.Key"/>
         /// </summary>
         public string DownstreamSwaggerEndPointBasePath { get; set; } = "/swagger/docs";
+
+        /// <summary>
+        /// Headers to include when requesting a downstream swagger endpoint.
+        /// </summary>
+        public IEnumerable<KeyValuePair<string, string>> DownstreamSwaggerHeaders { get; set; }
     }
 }

src/MMLib.SwaggerForOcelot/Middleware/SwaggerForOcelotMiddleware.cs

@@ -23,6 +23,7 @@ public class SwaggerForOcelotMiddleware
         private readonly Lazy<Dictionary<string, SwaggerEndPointOptions>> _swaggerEndPoints;
         private readonly IHttpClientFactory _httpClientFactory;
         private readonly ISwaggerJsonTransformer _transformer;
+        private readonly SwaggerForOcelotUIOptions _options;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="SwaggerForOcelotMiddleware"/> class.
@@ -45,6 +46,7 @@ public SwaggerForOcelotMiddleware(
             _reRoutes = Check.NotNull(reRoutes, nameof(reRoutes));
             Check.NotNull(swaggerEndPoints, nameof(swaggerEndPoints));
             _httpClientFactory = Check.NotNull(httpClientFactory, nameof(httpClientFactory));
+            _options = options;
 
             _swaggerEndPoints = new Lazy<Dictionary<string, SwaggerEndPointOptions>>(()
                 => swaggerEndPoints.Value.ToDictionary(p => $"/{p.KeyToPath}", p => p));
@@ -58,14 +60,23 @@ public async Task Invoke(HttpContext context)
         {
             var endPoint = GetEndPoint(context.Request.Path);
             var httpClient = _httpClientFactory.CreateClient();
-
+            AddHeaders(httpClient);
             var content = await httpClient.GetStringAsync(endPoint.Url);
             var hostName = endPoint.EndPoint.HostOverride ?? context.Request.Host.Value;
             content = _transformer.Transform(content, _reRoutes.Value.Where(p => p.SwaggerKey == endPoint.EndPoint.Key), hostName);
 
             await context.Response.WriteAsync(content);
         }
 
+        private void AddHeaders(HttpClient httpClient)
+        {
+            if (_options.DownstreamSwaggerHeaders == null) return;
+            foreach (var kvp in _options.DownstreamSwaggerHeaders)
+            {
+                httpClient.DefaultRequestHeaders.Add(kvp.Key, kvp.Value);
+            }
+        }
+
         /// <summary>
         /// Get Url and Endpoint from path
         /// </summary>