Setting up Swagger (ASP.NET Core) using the Authorization headers (Bearer)

ApiKeyScheme was deprecated, in version 5 you can use like this:

services.AddSwaggerGen(c =>
  {
    c.SwaggerDoc("v1", new Info { Title = "You api title", Version = "v1" });
    c.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
      {
        Description = @"JWT Authorization header using the Bearer scheme. \r\n\r\n 
                      Enter 'Bearer' [space] and then your token in the text input below.
                      \r\n\r\nExample: 'Bearer 12345abcdef'",
         Name = "Authorization",
         In = ParameterLocation.Header,
         Type = SecuritySchemeType.ApiKey,
         Scheme = "Bearer"
       });

    c.AddSecurityRequirement(new OpenApiSecurityRequirement()
      {
        {
          new OpenApiSecurityScheme
          {
            Reference = new OpenApiReference
              {
                Type = ReferenceType.SecurityScheme,
                Id = "Bearer"
              },
              Scheme = "oauth2",
              Name = "Bearer",
              In = ParameterLocation.Header,

            },
            new List<string>()
          }
        });
    var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
    var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
    c.IncludeXmlComments(xmlPath);
});

---

First of all, you can use Swashbuckle.AspNetCore nuget package for auto generating your swagger definition. (tested on 2.3.0)

After you've installed package, setup it in Startup.cs in method ConfigureServices

services.AddSwaggerGen(c => {
    c.SwaggerDoc("v1", new Info { Title = "You api title", Version = "v1" });
    c.AddSecurityDefinition("Bearer",
        new ApiKeyScheme { In = "header",
          Description = "Please enter into field the word 'Bearer' following by space and JWT", 
          Name = "Authorization", Type = "apiKey" });
    c.AddSecurityRequirement(new Dictionary<string, IEnumerable<string>> {
        { "Bearer", Enumerable.Empty<string>() },
    });

});

Then you can use Authorize button at the top right of the page.

At least you can try to use this package to generate valid swagger definition

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TIP!

To avoid always write the keyword Bearer on the Swagger(a.k.a Swashbuckle) auth dialog, like: "bearer xT1...", you can use the code/config below on ConfigureServices(...) method at your Startup class:

using Microsoft.OpenApi.Models;
...


services.AddSwaggerGen(setup =>
{
    // Include 'SecurityScheme' to use JWT Authentication
    var jwtSecurityScheme = new OpenApiSecurityScheme
    {
        Scheme = "bearer",
        BearerFormat = "JWT",
        Name = "JWT Authentication",
        In = ParameterLocation.Header,
        Type = SecuritySchemeType.Http,
        Description = "Put **_ONLY_** your JWT Bearer token on textbox below!",

        Reference = new OpenApiReference
        {
            Id = JwtBearerDefaults.AuthenticationScheme,
            Type = ReferenceType.SecurityScheme
        }
    };

    setup.AddSecurityDefinition(jwtSecurityScheme.Reference.Id, jwtSecurityScheme);

    setup.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        { jwtSecurityScheme, Array.Empty<string>() }
    });

});

We can make this, only by changing the Type property of the OpenApiSecurityScheme class to:

Type = SecuritySchemeType.Http

instead

Type = SecuritySchemeType.ApiKey.

https://i.stack.imgur.com/88nJd.png

https://i.stack.imgur.com/EjHEY.png

Packages:

Swashbuckle.AspNetCore(5.6.3)
Swashbuckle.AspNetCore.SwaggerUI(5.6.3)

I'am using .NET Core 3.1, and hope this helps!

---

Using ASP.Net Core 3.1, here's what worked for me:

services.AddSwaggerGen(s =>
        {
            s.SwaggerDoc("v1", new OpenApiInfo
            {
                Version = "v1",
                Title = "Chat API",
                Description = "Chat API Swagger Surface",
                Contact = new OpenApiContact
                {
                    Name = "João Victor Ignacio",
                    Email = "ignaciojvig@gmail.com",
                    Url = new Uri("https://www.linkedin.com/in/ignaciojv/")
                },
                License = new OpenApiLicense
                {
                    Name = "MIT",
                    Url = new Uri("https://github.com/ignaciojvig/ChatAPI/blob/master/LICENSE")
                }

            });

            s.AddSecurityDefinition("Bearer", new OpenApiSecurityScheme
            {
                Description = "JWT Authorization header using the Bearer scheme (Example: 'Bearer 12345abcdef')",
                Name = "Authorization",
                In = ParameterLocation.Header,
                Type = SecuritySchemeType.ApiKey,
                Scheme = "Bearer"
            });

            s.AddSecurityRequirement(new OpenApiSecurityRequirement
            {
                {
                    new OpenApiSecurityScheme
                    {
                        Reference = new OpenApiReference
                        {
                            Type = ReferenceType.SecurityScheme,
                            Id = "Bearer"
                        }
                    },
                    Array.Empty<string>()
                }
            });

        });

---

There is no need to generate token separate and key in swagger. Swagger support generation part too. Below work for me with asp.net core 3.1 and keycloack auth.

swagger.AddSecurityDefinition(JwtBearerDefaults.AuthenticationScheme, new OpenApiSecurityScheme
{
    Type = SecuritySchemeType.OAuth2,
    Flows = new OpenApiOAuthFlows
    {
        Implicit = new OpenApiOAuthFlow
        {
            AuthorizationUrl = new Uri("https://youauthsrv.com/auth/realms/your-realm/protocol/openid-connect/auth"),
        }
    },
    In = ParameterLocation.Header,
    Scheme = JwtBearerDefaults.AuthenticationScheme,
});

swagger.AddSecurityRequirement(new OpenApiSecurityRequirement
{
    {
        new OpenApiSecurityScheme
        {
            Reference = new OpenApiReference
            {
                Type = ReferenceType.SecurityScheme,
                Id = JwtBearerDefaults.AuthenticationScheme
            }
        },
        new string[] {}
    }
});

in Configure

app.UseSwaggerUI(c =>
{
    c.OAuthClientId("clientname");
    c.OAuthRealm("your-realm");
});

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Currently Swagger has functionality for authentication with JWT-token and can automatically add token into header, I have answered here.

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