I would like to have authentication and authorization performed in a separate micro service. At the same time, my authorization micro service is not an identity provider, but rather a simple API.
How can I configure which endpoint in ASP.NET Core to use for authentication and what data to send to it before accessing the destination endpoint?
I found the following method in the documentation:
services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(options =>
{
// base-address of your identityserver
options.Authority = "https://demo.identityserver.io";
// name of the API resource
options.Audience = "api1";
});
Do I understand correctly that this is what I need, but it uses an identity server?
How can I accomplish this without using one?
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Implementing authentication and authorization in ASP.NET for a microservices architecture involves multiple steps and considerations to ensure secure and efficient user access control. Here’s a comprehensive guide on how to achieve this:
1. Authentication
Authentication verifies the identity of a user or service. In a microservices architecture, it’s common to use token-based authentication mechanisms such as JWT (JSON Web Tokens).
Steps for Implementing Authentication:
1.1. Centralized Authentication Service:
- Identity Provider (IdP): Use a centralized identity provider like IdentityServer4, Azure Active Directory, or Auth0. This service will handle user authentication and issue tokens.
- OAuth2/OpenID Connect: These protocols are widely used for implementing authentication in microservices. They allow applications to verify user identity and obtain limited access to user data.
1.2. Token Issuance:
- When a user logs in, the IdP issues a JWT containing user claims (identity information and permissions).
1.3. Token Validation:
- Each microservice needs to validate the incoming token. This can be done using middleware in ASP.NET Core.
Example Code:
Startup.cs for API Gateway or Microservice:
public void ConfigureServices(IServiceCollection services)
{
services.AddAuthentication("Bearer")
.AddJwtBearer("Bearer", options =>
{
options.Authority = "https://your-identity-provider";
options.TokenValidationParameters = new TokenValidationParameters
{
ValidateAudience = false
};
});
services.AddAuthorization(options =>
{
options.AddPolicy("ApiScope", policy =>
{
policy.RequireAuthenticatedUser();
policy.RequireClaim("scope", "api1");
});
});
services.AddControllers();
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseRouting();
app.UseAuthentication();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers()
.RequireAuthorization("ApiScope");
});
}
2. Authorization
Authorization determines what an authenticated user is allowed to do. In a microservices setup, authorization can be role-based (RBAC) or claim-based.
Steps for Implementing Authorization:
2.1. Role-Based Access Control (RBAC):
- Assign roles to users and define permissions based on roles.
- Use attributes in ASP.NET to enforce role-based authorization.
Example Code:
[Authorize(Roles = "Admin")]
public class AdminController : ControllerBase
{
// Actions that only Admin can access
}
2.2. Policy-Based Authorization:
- Define policies based on user claims.
Example Code:
services.AddAuthorization(options =>
{
options.AddPolicy("RequireAdminRole", policy => policy.RequireRole("Admin"));
options.AddPolicy("RequireUserClaim", policy => policy.RequireClaim("UserType", "Premium"));
});
[Authorize(Policy = "RequireAdminRole")]
public class AdminController : ControllerBase
{
// Actions that only users with Admin role can access
}
[Authorize(Policy = "RequireUserClaim")]
public class PremiumUserController : ControllerBase
{
// Actions that only users with the claim UserType = Premium can access
}
3. Token Propagation
In microservices, a request might pass through multiple services. Propagating the user’s identity and claims across services is crucial.
3.1. Token Forwarding:
- Use HttpClient to forward the token from one service to another.
Example Code:
public class SomeService
{
private readonly HttpClient _httpClient;
public SomeService(HttpClient httpClient)
{
_httpClient = httpClient;
}
public async Task CallAnotherService(string token)
{
_httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);
var response = await _httpClient.GetAsync("https://another-microservice/api/data");
response.EnsureSuccessStatusCode();
}
}