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1. **Dokumentation der Architektur:**
- Vervollständigen Sie die C4-Diagramme im docs-Verzeichnis
- Dokumentieren Sie die wichtigsten Architekturentscheidungen in ADRs
2. **Redis-Integration finalisieren:**
- Implementieren Sie die verteilte Cache-Lösung für die Offline-Fähigkeit
- Nutzen Sie Redis Streams für das Event-Sourcing
82 lines
4.0 KiB
Markdown
82 lines
4.0 KiB
Markdown
# ADR-0006: Authentication and Authorization with Keycloak
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## Status
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Accepted
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## Context
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As part of our microservices architecture ([ADR-0003](0003-microservices-architecture.md)), we needed a robust and centralized solution for authentication and authorization. Key requirements included:
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1. Single sign-on (SSO) across all services and applications
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2. Support for multiple authentication methods (username/password, OAuth, SAML)
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3. Fine-grained authorization with role-based access control (RBAC)
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4. User management capabilities including self-registration and profile management
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5. Integration with external identity providers
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6. Security best practices including password policies and account lockout
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7. Token-based authentication for service-to-service communication
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Implementing these features from scratch would be time-consuming and error-prone, and would divert resources from our core business functionality.
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## Decision
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We decided to use Keycloak (version 23.0) as our identity and access management solution. Keycloak is an open-source identity and access management solution that provides:
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1. **User Authentication**: Multiple authentication methods and flows
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2. **User Federation**: Integration with LDAP, Active Directory, and other user stores
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3. **Identity Brokering**: Integration with external identity providers (Google, Facebook, etc.)
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4. **Single Sign-On**: Across all applications and services
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5. **Fine-grained Authorization**: Role-based and attribute-based access control
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6. **User Management**: Self-registration, profile management, password policies
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7. **Token-based Authentication**: JWT tokens for service-to-service communication
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Our implementation includes:
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- Keycloak server deployed as a containerized service
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- Integration with our API Gateway for token validation
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- Client adapters for our services and applications
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- Custom themes and email templates
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- Role and group definitions aligned with our domain model
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## Consequences
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### Positive
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- **Comprehensive solution**: Keycloak provides a complete identity and access management solution
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- **Standards compliance**: Keycloak implements industry standards (OAuth 2.0, OpenID Connect, SAML)
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- **Reduced development effort**: We don't need to implement authentication and authorization from scratch
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- **Security**: Keycloak follows security best practices and is actively maintained
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- **Flexibility**: Keycloak supports multiple authentication methods and identity providers
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### Negative
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- **Operational complexity**: Keycloak adds another service to deploy and maintain
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- **Learning curve**: Teams need to learn Keycloak concepts and APIs
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- **Performance considerations**: Token validation adds some overhead to requests
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- **Dependency**: We are dependent on Keycloak for authentication and authorization
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### Neutral
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- **Configuration needs**: Keycloak requires careful configuration to align with our security requirements
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- **Upgrade management**: Keycloak upgrades need to be managed carefully
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## Alternatives Considered
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### Custom Authentication Service
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We considered building our own authentication service. This would have given us complete control over the implementation but would have required significant development effort and ongoing maintenance.
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### Auth0
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We considered using Auth0, a commercial identity as a service (IDaaS) solution. Auth0 would have provided similar capabilities to Keycloak with less operational overhead, but would have introduced ongoing costs and potential vendor lock-in.
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### Spring Security with JWT
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We considered using Spring Security with JWT tokens for authentication and authorization. This would have integrated well with our Spring-based services but would have required more development effort and would not have provided the comprehensive identity management features of Keycloak.
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## References
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- [Keycloak Documentation](https://www.keycloak.org/documentation)
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- [OAuth 2.0 and OpenID Connect](https://oauth.net/2/)
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- [JWT (JSON Web Tokens)](https://jwt.io/)
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- [Securing Microservices with Keycloak](https://www.keycloak.org/docs/latest/securing_apps/)
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