Implementing ASP.NET Core Identity with IdentityServer4 for Secure Authentication in Microservices

Описание: Discover how to effectively manage user access and authentication in a microservices environment using ASP.NET Core Identity and IdentityServer4. Learn best practices and troubleshooting tips!
---
This video is based on the question https://stackoverflow.com/q/63610115/ asked by the user 'Guy Lowe' ( https://stackoverflow.com/u/748133/ ) and on the answer https://stackoverflow.com/a/63610724/ provided by the user 'Tore Nestenius' ( https://stackoverflow.com/u/68490/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Using ASP.NET Core Identity with IdentityServer4 - Authentication

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Implementing ASP.NET Core Identity with IdentityServer4 for Secure Authentication in Microservices

In the rapidly evolving world of microservices, securing user access management and authentication can be a significant challenge. Have you found yourself wondering how to implement a robust security strategy for your applications? If so, you're not alone. Many developers seek clarity on utilizing ASP.NET Core Identity alongside IdentityServer4 to manage user credentials, handle token-based authentication, and cater to various clients such as web applications, internal APIs, and mobile apps.

In this guide, we’ll explore the implementation of authentication in a microservices environment using ASP.NET Core, while addressing concerns about service organization and troubleshooting common issues.

The Problem Defined

You may be trying to establish a single authentication service (a "gatekeeper") for all your clients to manage user access effectively. This includes:

A Blazor web application that requires username and password validation.

Internal APIs that authenticate using tokens.

A mobile application utilizing OAuth token and refresh token protocols.

However, you might face challenges, including determining whether to centralize or split your services and debugging authentication errors, such as receiving a 404 error instead of the expected 401.

Key Questions:

Is it advisable to keep services centralized or split them into distinct services?

Why am I encountering a 404 error when my intention is to receive a 401 in response to unauthorized access?

The Solution: A Closer Look

1. Service Organization: Separate Concerns

While it can be tempting to consolidate multiple clients and services under one authentication service for simplicity, it is generally recommended to separate IdentityServer from client applications and APIs. This separation helps you achieve:

Better scalability: Each service can be scaled independently as per its usage patterns.

Improved maintenance: Isolated services can be upgraded or debugged without affecting others.

Dedicated spaces for security policies: Different clients might have varying security requirements and policies.

Understanding the separation of concerns promotes cleaner architecture and enhances overall system security.

2. Troubleshooting the 404 Error

If you encounter a 404 status code while testing your API with Postman (indicating the API is redirecting to a login page), it’s likely due to the absence of an authorization challenge in the given setup.

Understanding Middleware Behavior

The AddIdentityServerAuthentication component only triggers upon receiving a challenge from the Authorization middleware, implying that:

Controllers and Actions: You need to apply the [Authorize] attribute to your controllers or specific actions to enable this behavior effectively.

Implementation Code Overview

The following is an abstraction of the necessary code for setting up ASP.NET Core Identity and IdentityServer4:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

When managing authentication in a microservices environment, leveraging ASP.NET Core Identity and IdentityServer4 can provide a powerful framework for securing your applications. Remember that separating your authentication service can facilitate better maintenance and scalability while ensuring that appropriate authorization mechanisms are always in place.

By addressing both the architectural considerations and practical troubleshooting steps, you'll be better positioned to implement a secure, effective user authentication system across your various clients.

Keep experimenting and refining your approach a