How can a mechanism for access rights verification be organized in a system built on microservice architecture?

In a microservices architecture, access control is usually implemented centrally or in a distributed manner, depending on security and scalability requirements.

Main approaches:

1. Centralized Authorization Service

   • All microservices trust a single service that issues access tokens (e.g., JWT).
   • Microservices validate and decode the token to check permissions.
   • Example: OAuth 2.0 + OpenID Connect.

2. API Gateway with access control

   • All requests pass through an API Gateway that checks permissions and only forwards authorized requests.
   • Microservices receive already validated requests.

3. Distributed validation within microservices

   • Each microservice independently checks permissions using information from the token or by contacting a centralized service.

Example of JWT usage in C#:

// Token validation and permission extraction
var handler = new JwtSecurityTokenHandler();
var jwtToken = handler.ReadJwtToken(tokenString);
var roles = jwtToken.Claims.Where(c => c.Type == "role").Select(c => c.Value);

if (roles.Contains("Admin")) {
    // Grant access
} else {
    // Deny
}

Thus, the key is to use tokens with access rights and centralized management of them to simplify support and security.