"Authorize" button not showing in Swagger UI (.NET 9)

Question

Here is my repo: https://github.com/FlameWolf/DotNet9WebApi

My Program.cs:

public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);
        builder.Services.AddControllers();
        builder.Services.AddOpenApi(options =>
        {
            options.OpenApiVersion = Microsoft.OpenApi.OpenApiSpecVersion.OpenApi3_0;
        });
        builder.Services.AddSwaggerGen(options =>
        {
            options.AddSecurityDefinition("bearerAuth", new()
            {
                Type = SecuritySchemeType.Http,
                In = ParameterLocation.Header,
                Scheme = "Bearer",
                BearerFormat = "JWT",
                Name = "Authorization",
                Description = "Enter your bearer token"
            });
            options.AddSecurityRequirement(new()
            {
                {
                    new()
                    {
                        Reference = new()
                        {
                            Type = ReferenceType.SecurityScheme,
                            Id = "bearerAuth"
                        }
                    },
                    Array.Empty<string>()
                }
            });
        });
        var app = builder.Build();
        if (app.Environment.IsDevelopment())
        {
            app.MapOpenApi();
            app.UseSwaggerUI(options =>
            {
                options.SwaggerEndpoint("/openapi/v1.json", "v1");
            });
            app.MapGet("/", async context =>
            {
                await Task.Run(() => context.Response.Redirect("./swagger/index.html", permanent: false));
            });
        }
        app.UseHttpsRedirection();
        app.UseAuthorization();
        app.MapControllers();
        app.Run();
    }
}

The same call to AddSwaggerGen used to work with .NET 8, where we had AddEndpointsApiExplorer instead of AddOpenApi, and UseSwagger instead of MapOpenApi. A big, beautiful "Authorize" button would be available in the Swagger UI. But now it doesn't. How can I fix this?

Answer 1

You can use document transformers like below:

1.Be sure install the package Microsoft.AspNetCore.Authentication.JwtBearer

<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.JwtBearer" Version="9.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.0" />
    
    <PackageReference Include="Swashbuckle.AspNetCore" Version="7.0.0" />
    
</ItemGroup>

2.Update your Program.cs like below

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.OpenApi;
using Microsoft.OpenApi.Models;

namespace DotNet9WebApi;

public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);
        builder.Services.AddControllers();
        builder.Services.AddAuthentication().AddJwtBearer();
        builder.Services.AddOpenApi(options =>
        {
            options.AddDocumentTransformer<BearerSecuritySchemeTransformer>();
            options.OpenApiVersion = Microsoft.OpenApi.OpenApiSpecVersion.OpenApi3_0;
        });
        var app = builder.Build();
        if (app.Environment.IsDevelopment())
        {
            app.MapOpenApi();
            app.UseSwaggerUI(options =>
            {
                options.SwaggerEndpoint("/openapi/v1.json", "v1");
            });
            app.MapGet("/", async context =>
            {
                await Task.Run(() => context.Response.Redirect("./swagger/index.html", permanent: false));
            });
        }
        app.UseHttpsRedirection();
        app.UseAuthorization();
        app.MapControllers();
        app.Run();
    }
}
internal sealed class BearerSecuritySchemeTransformer(IAuthenticationSchemeProvider authenticationSchemeProvider) : IOpenApiDocumentTransformer
{
    public async Task TransformAsync(OpenApiDocument document, OpenApiDocumentTransformerContext context, CancellationToken cancellationToken)
    {
        var authenticationSchemes = await authenticationSchemeProvider.GetAllSchemesAsync();
        if (authenticationSchemes.Any(authScheme => authScheme.Name == "Bearer"))
        {
            var requirements = new Dictionary<string, OpenApiSecurityScheme>
            {
                ["Bearer"] = new OpenApiSecurityScheme
                {
                    Type = SecuritySchemeType.Http,
                    Scheme = "bearer", // "bearer" refers to the header name here
                    In = ParameterLocation.Header,
                    BearerFormat = "Json Web Token"
                }
            };
            document.Components ??= new OpenApiComponents();
            document.Components.SecuritySchemes = requirements;
            foreach (var operation in document.Paths.Values.SelectMany(path => path.Operations))
            {
                operation.Value.Security.Add(new OpenApiSecurityRequirement
                {
                    [new OpenApiSecurityScheme { Reference = new OpenApiReference { Id = "Bearer", Type = ReferenceType.SecurityScheme } }] = Array.Empty<string>()
                });
            }
        }
    }
}

Reference: Use document transformers