Can't read swagger JSON file on ASP.NET Core 1.2 Application after hosting into local IIS - asp.net

Question

After hosting my asp.net core 1.2 application, I am getting an error as:
swagger is unable to find the swagger.json file.
I have tried to solve the problem by giving a virtual path name app.UseSwaggerUI() but it's not working.
Edit to clarify question based on comments:
After hosting Asp.net core application in IIS, the swagger.json file is generating on localhost:<random_port>/swagger/v1/swagger.json path.
How do I serve the swagger.json file on a custom route like:
localhost:<random_port>/virtualpathname/swagger/v1/swagger.json
I have tried to set a virtual path in app.UseSwaggerUI() like {virtualpathname}/swagger/v2/swagger.json but still it is not working

Answer 1

Could be a few reasons for this - one being that .Net Core doesnt serve static files by default (although looking at online examples this doesnt seem to be an issue).
If you havent already, try installing the package Microsoft.AspNetCore.StaticFiles and adding UseStaticFiles() in your Configure() method in Startup.cs with the following configuration. I dont think that the order is important, but this is the order I have mine running in a working app.
public void Configure(...)
{
// Enable middleware to serve static files (like .json)
app.UseStaticFiles();
//Enable middleware for your API
app.UseMvc();
// Enable middleware to serve generated Swagger as a JSON endpoint
app.UseSwagger();
// Enable middleware to serve swagger-ui assets (HTML, JS, CSS etc.)
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "YourApp API V1");
});
}
You will also need SwaggerGen middleware configured in your ConfigureServices() method.
services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1", new Info { Title = "api_name", Version = "1.0"});
});
Edit Based on comment - to serve swagger json on a custom route:
// Enable middleware to serve generated Swagger as a JSON endpoint on a custom endpoint
app.UseSwagger(c => c.RouteTemplate = "custom/swagger/{documentName}/swagger.json");
// Enable middleware to serve swagger-ui assets (HTML, JS, CSS etc.)
// Using custom endpoint defined above
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/custom/swagger/v1/swagger.json", "YourApp API V1");
});
If you need to serve SwaggerUI on a custom route as well, then:
// Enable middleware to serve swagger-ui assets (HTML, JS, CSS etc.)
// Using custom endpoint defined above
// And serving UI on a custom route
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/custom/swagger/v1/swagger.json", "YourApp API V1");
c.RoutePrefix = "custom"; // serves UI on http://{domain}:{port}/custom/
});

Answer 2

I suggest you to perform the two next steps.
First, open your project web.config and enable stdoutLogEnabled. (Remember to create the folder logs on your application folder and give it proper permissions)
Second, make sure you're doing the right configuration. (https://learn.microsoft.com/en-us/aspnet/core/tutorials/web-api-help-pages-using-swagger)
Note: The first step is going to give you more details about the error you're facing.

Answer 3

In my case the issue was the virtual directory which I fixed by adding a relative path(../). In any case make sure you setup ConfigureServices first, then when Configure make sure everything is in order, UseSwagger should be before UseMvc and at the end UseSwaggerUI
public void ConfigureServices(IServiceCollection services)
{
// Add framework services.
services.AddMvc();
services.AddSwaggerGen(c => {
c.SwaggerDoc("v1", new Swashbuckle.AspNetCore.Swagger.Info { Title = "Utility", Version = "v1" });
});
// initialize configuration
var conf = new ConfigurationHelper(Microsoft.DotNet.PlatformAbstractions.ApplicationEnvironment.ApplicationBasePath);
Configuration = conf.Configuration; // just in case
// inject the RestApiWrapperService as singleton into the services configuration
var restService = new RestApiWrapperService(conf);
services.AddSingleton<IRestApiWrapperService>(restService);
}
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
loggerFactory.AddConsole(Configuration.GetSection("Logging"));
loggerFactory.AddDebug();
app.UseSwagger();
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseBrowserLink();
}
else
{
app.UseExceptionHandler("/Home/Error");
}
app.UseStaticFiles();
// app.UseMvc();
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
});
app.UseSwaggerUI(s => {
s.RoutePrefix = "help";
s.SwaggerEndpoint("../swagger/v1/swagger.json", "Utility");
s.InjectStylesheet("../css/swagger.min.css");
});

Answer 4

Change the following on your startup.cs class:
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/swagger/v1/swagger.json", "MyService.API v1");
});
To
app.UseSwaggerUI(c =>
{
c.SwaggerEndpoint("/MyWebsiteName/swagger/v1/swagger.json",
"MyService.API v1");
});
[MyWebsiteName] being the name of application configured in IIS.

Answer 5

I happened to have a simple copy paste mistake!
see the first line in below code, the if statement env.IsDevelopment() is causing this section to not run when deployed to IIS. One option is to comment it out!
//if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
app.UseSwagger(c =>
{
c.RouteTemplate = "swagger/{documentName}/swagger.json";
});
app.UseSwaggerUI(c => {
c.RoutePrefix = "swagger";
c.SwaggerEndpoint("/swagger/v1/swagger.json", "StockOps.WebAPI v1");
});
}