Best Practices for Implementing Permissions in Keycloak

Keycloak is a popular open-source tool for managing identity and access control, offering both authentication and authorization features. While its built-in permissions system covers many use cases, setting it up correctly requires some planning to get the most out of it.

This guide will go over the best practices for configuring application permissions with Keycloak, helping you create an access control system that is effective, scalable, and secure.

An important point this article focuses on is the understanding that while Keycloak offers some decent built-in authorization capabilities that work well for basic scenarios, it may not be enough for modern applications with more complex access control needs. Knowing where its strengths and limits lie will help you make smarter configuration choices.

Without further adieu, let’s get to it -

Best Practices for Configuring Keycloak Authorization

Understanding the Authorization Flow

Key cloak's authorization service operates in three key phases:

Phase 1: Validate Token and Policy Check

When a user requests access to a resource, Keycloak first checks their token. This token includes user details, roles, and claims that influence authorization decisions. Proper token validation is key to preventing unauthorized access.

Best Practice: Keep token expiration times short to reduce security risks, and use refresh tokens to maintain a good balance between security and user experience.

Phase 2: Decision-Making with a Policy Engine

Keycloak evaluates access control rules using a policy engine. It supports role-based access control (RBAC) and attribute-based access control (ABAC) but lacks more advanced models like relationship-based access control (ReBAC).

Best Practice: Use Keycloak’s built-in policy engine for simple rules. If you need more advanced access control, consider integrating an external authorization system that supports ReBAC.

Phase 3: Enforcing Resource Access

Once access is approved, Keycloak updates the user’s token with the necessary permissions. The application then enforces these permissions at the resource level.

Best Practice: Ensure that access decisions are checked at multiple levels—both at Keycloak and within your application to avoid excessive trust in client-side enforcement.

Organizing Authorization Policies Efficiently

A well-structured authorization model prevents excessive complexity and ensures maintainability. Keycloak gives you different ways to define authorization rules, but they need to be used wisely.

Best Practices:

• Use Roles for broad permission groups (e.g., Admin, Manager, User).
• Use Attributes for finer-grained access control (e.g., “Can access reports if department = Finance”).
• Keep policies modular—avoid embedding logic directly into JavaScript policies.

If your application requires highly dynamic policies (e.g., permissions that change based on real-time data), Keycloak alone may not be enough. Consider integrating an external policy engine (Like OPA + OPAL) for dynamic fine-grained access control.

3. Managing Multi-Tenancy Effectively

If your application serves multiple tenants (customers, organizations, etc.), setting up authorization in Keycloak can get complicated.

Best Practices:

• Use separate realms if you need strict tenant isolation.
• If users need access across multiple tenants, instead of creating multiple realms, create a single realm with scoped roles.
• For more scalable multi-tenant setups, opt-in for solutions that support dynamic tenant-based access without requiring hardcoded configurations.

4. Ensuring Scalability & Performance

Keycloak is a monolithic system, which means it can struggle under heavy loads, especially when handling more fine-grained authorization checks.

Best Practices:

• Use external policy decision points (PDPs), such as to distribute authorization decisions instead of centralizing them in Keycloak.
• Cache authorization decisions where possible to reduce repeated evaluation overhead.
• Monitor Keycloak’s performance using built-in metrics and optimize database queries related to authorization checks.

Where Keycloak Built-in Authorization Might Not Be Enough?

Keycloak's built-in RBAC is sufficient for many applications, but modern security models require more dynamic access control mechanisms. Here’s where Keycloak might fall short:

Coarse-Grained Policies

• Authentication and Authorization Are Tightly Coupled

  Keycloak integrates authentication and authorization closely, making it difficult to separate them. This can be a challenge if you need to integrate different identity providers or enforce security across multiple independent systems.

• No Built-In Support for Relationship-Based Access Control (ReBAC)

  Keycloak does not natively support ReBAC, a model commonly used in advanced systems like Google Zanzibar. Instead, it primarily focuses on role-based access control (RBAC) and attribute-based access control (ABAC).

• Static and Monolithic Design

  Keycloak’s authorization engine is relatively static, making it difficult to enforce fine-grained access control dynamically. This limitation makes it less suited for event-driven architectures or microservices-based systems.

Complexity in Policy Management

• Difficult Multi-Tenant Configurations

  Setting up and managing multi-tenant policies in Keycloak requires significant effort. Ensuring that permissions remain consistent across tenants can be cumbersome.

• Limited Flexibility in Querying and Policy Definitions

  Keycloak’s query capabilities for dynamic policies are limited. Creating complex, attribute-based conditions is often challenging.

• Heavy Reliance on JavaScript-Based Policies

  Custom logic in Keycloak is primarily implemented using JavaScript policies. While functional, this approach can quickly become unmanageable in large-scale applications.

Operational and Scalability Constraints

• Lack of Centralized Policy Management Tools

  Keycloak’s admin dashboard focuses on realms, clients, and resources but lacks a dedicated interface for efficiently managing fine-grained policies.

• Scaling Keycloak for Dynamic Applications is Difficult

  Due to its monolithic architecture, Keycloak struggles with scaling its authorization service for high-performance applications.

Why These Limitations Matter

Keycloak is a solid option for simpler projects that require basic authorization. It can also perform well for small-scale applications with straightforward access control needs. However, as applications grow and security requirements become more complex, Keycloak’s limitations can become major roadblocks.

In real-world, user-facing applications, access control is rarely a simple yes-or-no decision. Instead, it involves intricate rules defining who can access what, under what conditions, and when. While Keycloak excels at authentication, its built-in authorization features often lack the depth and flexibility required for dynamic, modern applications.

Enhancing Keycloak Permissions

To overcome the limitations of Keycloak’s built-in authorization, integrating Keycloak with Permit.io provides a comprehensive and scalable solution for fine-grained access control. This combination allows you to enhance security, flexibility, and scalability while addressing Keycloak's shortcomings.

Why Combine Keycloak with Permit.io?

Decouple Authentication from Authorization – Keycloak efficiently manages authentication, while Permit.io handles dynamic authorization without the constraints of Keycloak’s monolithic architecture.

Enable Fine-Grained Access Control – Permit.io can be used to enhance Keycloak authorization by adding Attribute-Based Access Control (ABAC) and Relationship-Based Access Control (ReBAC) for more dynamic, context-aware permissions.

Simplify Policy Management – Instead of relying on static JavaScript-based policies, Permit.io provides a no-code and API-driven approach, making it easier to define, manage, and debug policies.

Enhance Multi-Tenancy Support – Managing permissions across multiple tenants in Keycloak can be complex. Permit.io simplifies tenant-aware authorization without requiring hardcoded rules.

Improve Scalability – Keycloak’s monolithic design limits its ability to scale fine-grained authorization checks efficiently. Permit.io enables decentralized policy enforcement, reducing authorization bottlenecks.

Keycloak’s built-in authorization features work well for many applications but may not be enough for more dynamic access control needs. By following best practices and integrating external tools when needed, you can ensure a more secure, flexible, and scalable authorization system.

⁠Next Steps

Here are some actionable steps to further enhance your Keycloak authorization system:

• Read how you can Enhance Keycloak authorization with ABAC and ReBAC in this step-by-step guide.

• Sign up for Permit.io to start building advanced authorization workflows tailored to your application's needs.

• Dive into the documentation for detailed guides and API references.

• Understand the differences between RBAC, ABAC, and ReBAC in our in-depth guide.

• Got questions or ideas? Join the Permit.io Slack community to connect with other developers building authorization systems.