Using Azure B2C gave me a bit of difficulty when I was trying to use the Swagger Gen on a .Net 6 application. Hopefully this will help others who were having the same issue.
Setting up Azure B2C
To start, I setup my Azure B2C using the Microsoft Docs – https://docs.microsoft.com/en-us/azure/active-directory-b2c/tutorial-create-tenant
We will want to create and register an application for Swagger.
During the creation make sure to set the redirect URI to https://localhost:<port>/swagger/oauth2-redirect.html
Also, make sure both Access tokens and ID tokens are checked.
Creating The App
Next I created a .Net 6 application where I attempted to add MicrosoftIdentityWebApi.
When I first tried to use Swagger to make an authorized request, I was receiving an error, which I was unable to find the root cause for was System.InvalidOperationException: IDX20803: Unable to obtain configuration from: 'System.String'
Because of this I had to change the following in my Program.cs
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddMicrosoftIdentityWebApi(builder.Configuration.GetSection("AzureAdB2C"));To this
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(jwtOptions =>
{
jwtOptions.Authority = $"{builder.Configuration["AzureAdB2C:Instance"]}/{builder.Configuration["AzureAdB2C:TenantId"]}/{builder.Configuration["AzureAdB2C:SignUpSignInPolicyId"]}/v2.0/";
jwtOptions.Audience = builder.Configuration["AzureAdB2C:ClientId"];
});Next I added the Swagger Configuration. This tells Swagger how to authenticate, what roles to request, and how to send the token on API requests.
builder.Services.AddSwaggerGen(o =>
{
o.AddSecurityDefinition("oauth2", new OpenApiSecurityScheme
{
Type = SecuritySchemeType.OAuth2,
Flows = new OpenApiOAuthFlows
{
Implicit = new OpenApiOAuthFlow
{
Scopes = new Dictionary<string, string>
{
{
"https://<company>.onmicrosoft.com/<Client Id>/weather.read",
"Access weather"
},
},
AuthorizationUrl =
new Uri("https://<company>.b2clogin.com/<company>.onmicrosoft.com/<name of user flow>/oauth2/v2.0/authorize"),
TokenUrl = new Uri("https://<company>.b2clogin.com/<company>.onmicrosoft.com/<name of user flow>/oauth2/v2.0/token")
}
},
BearerFormat = "JWT",
In = ParameterLocation.Query,
Scheme = "bearer"
});
o.AddSecurityRequirement(new OpenApiSecurityRequirement() {
{
new OpenApiSecurityScheme {
Reference = new OpenApiReference {
Type = ReferenceType.SecurityScheme,
Id = "oauth2"
},
Scheme = "oauth2",
Name = "oauth2",
In = ParameterLocation.Header,
},
new List <string> ()
}
});
});You can get the AuthorizationUrl and TokenUrl by clicking on your B2C client, going to Application Registration, and selecting endpoints.
This will open a blade that shows all the endpoints for the apps.
Lastly I configured Swagger UI.
if (app.Environment.IsDevelopment())
{
app.UseSwagger();
app.UseSwaggerUI(s =>
{
// Add this if you want to avoid having to enter the client ID each time.
s.OAuthClientId("<clientId>");
});
}Once all that was in place I was able to run the application, click the Authenticate button, log in using Azure B2C, and make an authenticated request.