Problems with Keycloak: Unpacking the Challenges

Here at Sirius, we often get asked, "What are the common problems or challenges we can expect when implementing Keycloak?" This is a very good question, and one that deserves a clear, honest answer. We understand the need to know the true operational and technical implications of any technology choice, as it's a decision a business will have to live with for years.

We want to be upfront: while Keycloak is a powerful and flexible Open Source Identity and Access Management (IAM) solution, and "free" in terms of licensing, the truth is, it comes with a unique set of complexities and challenges that can significantly impact its Total Cost of Ownership (TCO) and operational success. In fact, many organizations find that its immense power is a double-edged sword, leading to a steep learning curve, demanding specialized expertise, and introducing unexpected operational burdens. This article will transparently explain the most common problems and architectural challenges associated with Keycloak, helping you understand what might go wrong, what to prepare for, and ultimately, decide what is best for your specific needs. We aim to be fiercely transparent, allowing you to make the most informed decision possible.

You Ask, We Answer: Unpacking the Problems with Keycloak

The widespread adoption of Keycloak, driven by its robust feature set and Open Source nature, often leads to overlooking significant complexities inherent in its implementation and maintenance. When considering a core security platform, it's natural for potential adopters to worry more about what might go wrong than what will go right, and openly addressing these concerns is surely a most sensible step…

This article will outline the key problems and challenges users often encounter, providing an in-depth analysis to help you make an informed decision.

The Total Cost of Ownership (TCO) Paradox: Unpacking the "Free" Solution

The most significant misconception surrounding Keycloak is that its zero-dollar licensing fee equates to a low-cost solution. While Keycloak indeed offers a free license, this "free software" actually carries a high Total Cost of Ownership (TCO). The costs are not direct subscriptions but are instead shifted to substantial investments in "production-grade systems and skilled engineering time" for both initial setup and ongoing upkeep. This operational burden is a critical pain point for many organizations and developers.

For example, a three-year TCO analysis compares Keycloak's operational costs at $142,200, based on more than 3 hours of weekly maintenance, versus just $19,500 for a commercial alternative. The total cost for Keycloak over three years is projected to be between $199,200 and $211,200, which is more than $113,000 higher than a comparable commercial solution. This financial reality is a direct consequence of Keycloak's complexity and its demand for a deep understanding of its internal workings, including Java, networking, and database management. This specialized knowledge is both expensive and in high demand, making the cost of skilled labor and the time required for setup and maintenance the true price of the platform. This dynamic confirms that the decision to adopt Keycloak "cannot be based on its free price tag alone".

This table illustrates that operational costs represent the most significant financial differential, driven by a minimum of 3+ hours per week of specialized maintenance for Keycloak. The platform's power and flexibility, while attractive, necessitate a high investment in skilled labor, effectively moving the TCO from a fixed licensing cost to variable and often underestimated operational expenditures.

Core Operational and Developer Pain Points

Keycloak's day-to-day use presents a range of challenges for developers and administrators, indicating that its strength in customization and features is also a primary source of frustration.

A Steep Learning Curve and the Unintuitive Admin Console

The Admin Console is frequently described as "not intuitive" and difficult to navigate for those not already specialized in Identity and Access Management (IAM). The sheer number of configuration options can be overwhelming, with new teams reporting a "very slow learning" process. This isn't just a superficial UI issue; it's a direct consequence of Keycloak's architectural design, which prioritizes power and granular control for complex enterprise scenarios. This design choice creates a dependency on hiring or training specialized personnel, reinforcing the high operational TCO. The "bad UI" is a symptom of a design trade-off that favors power over simplicity, making Keycloak a platform best suited for experts.

The Burden of Customization and Extensions

Effective management and customization of Keycloak require a skilled team with deep knowledge of Java, networking, and databases. Its extensibility model, relying on the Service Provider Interface (SPI), demands advanced Java programming knowledge to create custom extensions. Developers report that the need to "upload a jar in order to be able to execute custom flows" is a significant pain point, and modifying the platform is described as "not fun".

The Open Source nature of Keycloak, which promises ultimate flexibility, can paradoxically create a form of technological lock-in due to its Java-based core and tightly coupled extensibility model. This reliance on a specific technology stack can limit an organization's talent pool and increase hiring costs for teams not specialized in JVM technologies. While Keycloak is Open Source, its extensibility model can create a "vendor" dependency on a specific programming language and ecosystem, hindering adoption for teams using non-JVM technologies.

Architectural and Migration Challenges

Keycloak's evolving architecture and rapid development cycle place a substantial and continuous maintenance burden on organizations, particularly evident in its major version updates.

The Disruptive WildFly-to-Quarkus Migration

A significant challenge for users has been the upgrade to Keycloak 17 and later, which involved a fundamental architectural shift from WildFly to the Quarkus framework. This was not a simple, automated upgrade, but introduced major breaking changes affecting configurations, endpoints, and custom provider implementations. For example, custom providers needed to be rebuilt for Quarkus's immutable runtime, default base paths changed, and Dockerfile/deployment workflows were overhauled. This architectural pivot, while offering performance gains, created a "large one-time migration" for existing users, highlighting a key risk of using a fast-evolving Open Source project for mission-critical systems. Users are forced to absorb the costs and complexities of a major architectural re-platforming.

A Fragile Upgrade Path

The community and official documentation generally "discourage the upgrade of a Keycloak cluster by jumping multiple major releases" due to continuous changes that break backward compatibility. These issues include incompatible cached data, alterations to the base theme affecting custom themes, and SPI changes rendering custom extensions unusable. The rapid release cycle (new versions every six months) further exacerbates this, forcing organizations to maintain a continuous, multi-step upgrade pipeline that is time-consuming and labor-intensive. Unlike commercial solutions where a vendor manages major version jumps, a self-hosted Keycloak deployment requires an organization to effectively become its own software maintenance team, contributing to high operational costs.

The Intricacies of Scalability and High Availability (HA)

Deploying Keycloak for high-load, mission-critical production environments reveals that scalability is not a simple, "out-of-the-box" feature, requiring a fundamental shift from development-grade to production-ready configurations.

From Development to Production: Database and Caching Pitfalls

While Keycloak can work "reliably and smoothly" in development, production use demands utmost reliability. A critical pitfall is the default in-memory database in the standard Docker image, which causes data loss upon container restart. Production deployments require a persistent database like PostgreSQL or MariaDB, configured for replication and high availability. The embedded Infinispan cache, while powerful, is not optimized for clusters spanning multiple availability zones (AZs) and can lead to data loss if multiple nodes leave the cluster concurrently. This contrast creates a "bait-and-switch" effect, where initial ease of adoption is followed by complex, non-obvious problems when attempting to go to production.

High-availability deployments require nuanced architectural decisions balancing cost and failover speed.

The Multi-Tenancy Scalability Barrier

Keycloak struggles to scale beyond a certain number of realms, which can be a fundamental barrier for large-scale multi-tenanted solutions. This is an architectural limitation stemming from inefficient JPA collection loads and a recursive role traversal algorithm that is inefficient for large numbers of roles. Operations like realm creation and Admin Console loading degrade exponentially with realm growth, making the system practically unusable beyond 100 to 200 realms. This limitation significantly challenges Keycloak's viability for SaaS providers who provision a separate tenant (realm) for each customer, affecting a large and growing market segment.

Security Vulnerabilities and the Community-Driven Approach

While an open approach to vulnerability management is a stated goal, Keycloak's community-driven model places a significant and continuous responsibility on the end-user to maintain a secure posture.

Known Vulnerabilities and Exploits

A continuous stream of reported and patched vulnerabilities is a constant concern; a deployed instance is only as secure as its last patch. Recent vulnerabilities include:

• CVE-2024-8698: Privilege Escalation and User Impersonation due to a flaw in SAML signature validation.
• CVE-2024-7260: Phishing Attacks and Data Theft due to improper URL validation in redirects.
• CVE-2023-6787: Session Hijacking and Account Takeover due to an error in the re-authentication mechanism.
• CVE-2023-6563: Denial of Service (DoS) from unconstrained memory consumption.

These vulnerabilities, especially in core functionalities, indicate that Keycloak's security is not a "set-and-forget" feature. Organizations must have a robust, proactive security response team dedicated to monitoring advisories, testing new versions, and applying patches promptly, adding substantial operational cost and risk to the TCO.

Misconfiguration as a Security Risk

The complexity of Keycloak's configuration can lead to misconfigurations that become vulnerabilities. Examples include SSO redirect loops from misconfigured realm settings and improper SAML assertion validation leading to unauthorized access. The vast number of granular options and steep learning curve increase the likelihood of human error or oversight, transforming complexity into a "vulnerability surface". A Keycloak instance, even if patched, can be insecure if the operating team lacks deep expertise for proper configuration, making the platform's flexibility a significant source of operational risk.

The Ecosystem: Support, Documentation, and Community Limitations

Keycloak's Open Source, community-driven ecosystem provides flexibility but lacks the guarantees of a commercial support contract, creating significant operational risks for enterprise-level deployments.

The Gap in Official Documentation

A frequent complaint is that the official documentation is lacking, often covering only simple scenarios and failing to provide adequate direction for complex, real-world setups. This gap is a trade-off of Open Source projects versus commercial products. Keycloak's community-maintained documentation, often written by developers, can prioritize code over exhaustive explanations, offloading the burden of understanding complex features onto the end-user. This forces reliance on trial-and-error, external blogs, or expensive consulting services, a hidden cost that directly impacts the TCO.

The Double-Edged Sword of Community Support

Support for Keycloak depends largely on the community and third-party vendors. While community channels (Slack, GitHub Discussions, mailing lists) exist, support is not guaranteed to be "immediate or comprehensive". The community model lacks a formal Service-Level Agreement (SLA), which is critical for mission-critical systems. In an outage or time-sensitive security issue, a team cannot rely on a community forum for timely resolution, forcing organizations to accept higher risk or pay for a third-party support contract, which adds to the TCO.

Keycloak in Context: A Strategic Comparative Analysis

The problems identified are not flaws in Keycloak itself, but consequences of its architectural and operational model. A strategic comparison with market alternatives clarifies when this model is appropriate for an organization.

Keycloak vs. Commercial Solutions (Auth0, ForgeRock, FusionAuth)

The primary trade-off is control versus simplicity. Keycloak offers full control for on-premises deployment, critical for regulatory and data residency requirements, but demands significant technical expertise for management. Commercial IDaaS solutions like Auth0 offer hassle-free setup, robust security, and professional support, but at a subscription cost. The choice is less about features (as most offer similar core sets) and more about organizational capability and risk appetite. Keycloak's model, offloading the operational burden to the user, is viable only for organizations with a dedicated, highly skilled team of IAM, DevOps, and Java experts. For those lacking this expertise, a commercial solution, despite higher licensing costs, may be more strategic, lower-risk, and ultimately more cost-effective.

Keycloak vs. Other Open Source and Cloud-Native Solutions (AWS Cognito)

Even within Open Source, Keycloak's heavyweight, Java-based architecture requires significant expertise and self-hosting, while alternatives like AWS Cognito are more lightweight, hosted solutions tightly integrated into the AWS ecosystem. Cognito offers a simpler setup but has its own learning curve and can be limited in customization. This fundamental architectural difference dictates the required skill sets and operational models. Keycloak's reliance on a specific technology stack creates both its power and its key limitations, meaning adopting it is a commitment to the long-term maintenance and operational overhead of its underlying ecosystem.

Conclusion & Strategic Recommendations

This analysis confirms that Keycloak is a powerful, enterprise-grade solution providing immense control over security infrastructure. However, this power comes at a significant price, not in licensing fees, but in operational work and the need for a specialized team. Keycloak is a "full-scale engineering project" requiring continuous investment in maintenance, security, and architectural management.

Based on these findings, we offer the following strategic recommendations:

• For Small to Mid-Sized Organizations: A careful evaluation of TCO beyond licensing fees is critical. Unless a dedicated DevOps or IAM team with strong Java expertise is available, a managed, commercial solution may prove more cost-effective and secure in the long run.
• For Enterprise-Level Deployments: Keycloak should be treated as a core piece of infrastructure. A dedicated, specialized team, internal or brought in, should be allocated for setup, tuning, and ongoing maintenance. The costs of a third-party support contract should be factored in to mitigate risks from community-only support.
• For Multi-Tenant Platforms: Acknowledge the architectural scalability limitations. Organizations should conduct thorough load testing and consider alternative solutions if their business model requires thousands of distinct tenants.
• For All Adopters: Develop a robust and proactive upgrade strategy. Skipping major versions is not viable, and significant engineering time should be allocated for managing breaking changes introduced by new releases.

In its truest form, Keycloak is a testament to the power of Open Source, but it is a solution for builders. The decision to adopt it is a commitment to building and maintaining a critical piece of a technology stack, a trade-off that should be made with a full and nuanced understanding of the responsibilities involved.