Blazor Redirection on IIS swagger - asp.net-core

Question

I have a .NET 5 blazor WASM (with core server) solution.
I added swagger (nswag) like this:
public class Startup {
public void ConfigureServices(IServiceCollection services) {
services.AddControllersWithViews();
services.AddRazorPages();
services.AddAuthentication(NegotiateDefaults.AuthenticationScheme).AddNegotiate();
services.AddSwaggerDocument(); //SWAGGER
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env) {
if(env.IsDevelopment()) {
app.UseDeveloperExceptionPage();
app.UseWebAssemblyDebugging();
}
else {
app.UseExceptionHandler("/Error");
// The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
app.UseHsts();
}
app.UseHttpsRedirection();
app.UseBlazorFrameworkFiles();
app.UseStaticFiles();
// Register the Swagger generator and the Swagger UI middlewares
app.UseOpenApi();
app.UseSwaggerUi3();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints => {
endpoints.MapRazorPages();
endpoints.MapControllers();
endpoints.MapFallbackToFile("index.html");
});
}
}
When I debug the appliation with IIS-Express and enter the address https://localhost:12234/swagger the swagger UI is displayed correctly.
But after deployment to IIS every address loads the blazor UI with "Sorry there is nothing at this address" instead of the swagger UI.
When I use an old IE (not able to run wasm) I get at least a title from swagger - so swagger is there on the server, but some "magic redirection" forces index.html to be loaded - no matter what I do.
By the way - I can call controller methods and a curl .../swagger/v1/swagger.json also works as expected.
How can I tell the app to accept URLs from the address line without redirection to index.html?
I use PWA and https in my project.

Answer 1

I found the solution.
There is a service-worker.published.js as a "subfile" in wwwroot/service-worker.js.
And there is code like this:
async function onFetch(event) {
let cachedResponse = null;
if (event.request.method === 'GET') {
// For all navigation requests, try to serve index.html from cache
// If you need some URLs to be server-rendered, edit the following check to exclude those URLs
const shouldServeIndexHtml = event.request.mode === 'navigate';
const request = shouldServeIndexHtml ? 'index.html' : event.request;
const cache = await caches.open(cacheName);
cachedResponse = await cache.match(request);
}
return cachedResponse || fetch(event.request);
}
After a little change everthing works fine now:
async function onFetch(event) {
let cachedResponse = null;
if (event.request.method === 'GET') {
// For all navigation requests, try to serve index.html from cache
// If you need some URLs to be server-rendered, edit the following check to exclude those URLs
const shouldServeIndexHtml = event.request.mode === 'navigate' && !event.request.url.includes('/swagger') && !event.request.url.includes('/api/');
const request = shouldServeIndexHtml ? 'index.html' : event.request;
const cache = await caches.open(cacheName);
cachedResponse = await cache.match(request);
}
return cachedResponse || fetch(event.request);
}
Adding two more conditions to shouldServeIndexHtml solved the problem.
const shouldServeIndexHtml = event.request.mode === 'navigate' && !event.request.url.includes('/swagger') && !event.request.url.includes('/api/');