Table of Contents
The rapid adoption of Kubernetes, and container-based solutions in general, has changed the way companies deliver software to a global audience—and a new class of problems has come with it. In particular, managing Kubernetes resources is becoming its own challenge. An organization without proper coordination or centralized management may soon have a significant number of Kubernetes clusters distributed throughout its infrastructure. This Kubernetes cluster sprawl can be a real obstacle for growth.
Cluster sprawl in Kubernetes can happen easily with diverse application requirements, distributed multi-cluster architectures, faster turnaround time, and autonomous team activities. Let’s take a closer look at the challenges this can bring, but don’t worry! We’ll talk about how to properly mitigate cluster sprawl, as well.
What Is Kubernetes Cluster Sprawl?
Cluster sprawl refers to the creation and management of Kubernetes clusters in an uncontrolled manner. With no coordination, governance, or centralized management around cluster creation, certain situations are perfect breeding grounds for sprawl.
Diverse Application Requirements
If your organization has several applications with different environmental requirements, their environments probably have different resource needs, security considerations, and regulatory compliance standards. And that usually means lots of separate Kubernetes clusters.
Plus, if you have multiple applications pinned to specific Kubernetes versions, your operations teams have to manage distinct clusters for them. That can quickly get out of hand and lead to sprawl.
Multi-cluster Architecture
A single Kubernetes cluster can accommodate up to 5,000 nodes, but having more firepower doesn't solve every problem. You might need multiple clusters to address issues like isolation and fault tolerance, scalability, and risk mitigation.
You might need multiple clusters to meet varying performance requirements, but if there’s a lack of centralized governance and visibility into which clusters do what and why, teams may end up creating separate clusters for similar purposes. Redundant clusters equal cluster sprawl.
Different Internal Approaches to Cluster Management
Different teams within the same organization often have separate requirements, policies, and configurations for their Kubernetes resources. That can create inconsistencies across divisions as to how clusters are created and maintained. Since cluster operators lack the authority to define user roles, access levels, and responsibilities centrally, they often unintentionally contribute to Kubernetes cluster sprawl.
Pressure to Innovate Quickly
As the market becomes increasingly competitive, developers are under pressure to introduce new features faster than ever. This rush to implement innovation often means that developers need to leverage cutting-edge technologies without a clear governance program for their clusters. Using the latest software stacks without proper governance leads to sprawl that becomes very hard to manage in the long term.
Drawbacks of Kubernetes Cluster Sprawl
Cluster sprawl can have severe negative impacts on your enterprise. In general, it increases the management complexity of your clusters, drives operational cost higher, and makes it hard to enforce security policies and monitoring.
Increased Complexity
Each cluster needs to be monitored, maintained, and upgraded individually, which leads to management overhead. Operations teams must manage multiple sets of configurations, policies, and security measures across sprawled clusters. The inconsistency across the sprawl makes it difficult to implement best practices, troubleshoot performance issues, and introduce new changes uniformly, which can exacerbate cluster sprawl.
Reduced Visibility
Sprawl makes it challenging to monitor cluster health, performance, and resource utilization over time. This lack of uniform infrastructure visibility can affect capacity planning, resource optimization, and troubleshooting efforts. Engineering teams that want insight into cluster health must cobble together DIY methods that are not only counterproductive but also hinder centralized governance and policy enforcement.
Poor Developer Experience
Cluster sprawl makes navigating and working with diverse environments a challenge. Each cluster might have its own configurations, access controls, and policies, creating fragmentation and inconsistencies in the developer experience. That can result in a steep learning curve for new team members.
At the end of the day, a lack of centralized governance and standardized policies around cluster creation leads to team confusion and wasted development hours.
High Operational Costs
Each new cluster has its own set of resource requirements. This includes compute nodes, storage plans, and networking policies. As resources are duplicated across multiple clusters instead of being effectively shared and utilized within a centralized environment, costs rise for infrastructure as well as management.
Simply identifying and resolving issues is more challenging with more clusters—it takes extra effort and resources to diagnose and solve problems. That may mean increased downtime for your system, and all the costs associated with that.
How to Manage Kubernetes Cluster Sprawl
As cluster sprawl threatens how your business operates, it's essential to implement the necessary safeguards to tackle this problem. Implementing a good management solution is mandatory to handle out-of-control cluster growth. Here're some practical strategies you can use to manage Kubernetes cluster sprawl.
Centralized Management
A centralized management system provides a unified platform for managing, monitoring, and controlling multiple Kubernetes clusters. By containing cluster sprawl and consolidating cluster management, you can reduce complexity, improve resource utilization, and enhance visibility across your entire infrastructure. Other benefits include better security, simplified troubleshooting, and streamlined deployment.
A single pane of glass view simplifies cluster administration while making it easier to identify and address potential issues affecting your clusters. Teams can enforce consistent configurations and policies across all clusters, which in turn minimizes the chance of conflicts that can arise when managing clusters independently.
Centralized management enables teams to monitor and optimize resource usage across all clusters, helping to prevent overprovisioning and underutilization. It’s a great way to make the most out of your infrastructure and cut unnecessary costs.
A robust centralized management system allows you to implement granular access control policies, reducing the risk of unauthorized access and making it easier to manage permissions across your organization.
Have a Proper Approach to Multi-tenancy
In Kubernetes, multi-tenancy refers to multiple tenants (ie workloads or teams) using the same cluster. This prevents cluster sprawl by allowing multiple teams or applications to share the same cluster while maintaining isolation and resource control.
Instead of creating a separate cluster for each team or application, create isolated environments within a single cluster using namespaces and other Kubernetes features. This reduces the overall number of clusters your organization requires and makes efficient use of your resources, cutting operational costs.
You can implement multi-tenancy in Kubernetes by either using separate namespaces for each tenant or adopting a virtual cluster solution like vcluster. Vcluster helps implement multi-tenancy by creating lightweight, fully functional Kubernetes clusters within an existing cluster. These virtual clusters share the underlying infrastructure and resources while providing an isolated environment that you can manage independently.
Embrace GitOps at Scale
GitOps is an operational framework that leverages version control systems like Git to standardize application deployments and rollouts. You get an excellent audit trail of your deployments, and you can see what went wrong when disaster strikes.
With a GitOps process in place, teams can enable automated provisioning, configuration, and lifecycle management of clusters, ensuring consistency and reducing manual efforts. Since the desired state of your applications is stored in a Git repo, you can apply deployment and configuration changes rapidly without worrying about cluster drift.
While GitOps processes alone don’t directly prevent cluster sprawl, they do promote good practices around cluster configuration and deployment. Combine GitOps with proper cluster governance, resource monitoring, and lifecycle management, and you can effectively control Kubernetes cluster sprawl.
Enable Self-service for Developers
Developer self-service allows teams to spin up clusters as needed. By having the ability to manage their own infrastructure, engineers can streamline cluster provisioning, reduce administrative overhead, and increase the speed of application development.
With self-service capabilities, developers don't need to wait on Ops teams to provision clusters for them. For example, tools like Loft allow you to spin up ephemeral clusters for CI testing while ensuring test reproducibility with virtual cluster templates. Loft also empowers developers to run integration tests themselves through the use of self-service virtual clusters.
Put simply, self-service enables teams to manage their own Kubernetes resources. No need to create a bottleneck by asking Ops teams to provision clusters on an individual basis. Ensuring that developers consume only the necessary resources helps optimize resource utilization and prevent cluster sprawl.
Conclusion
Kubernetes cluster sprawl is a common problem for organizations that haven’t developed effective methods for controlling their cluster resources. Sprawl leads to increased management complexity, reduced visibility, poor developer experience, and high operational costs.
Fortunately, you can mitigate this problem by adopting any of several effective strategies, such as a centralized management policy, a proper multi-tenancy approach, smart GitOps implementation, and enabling self-service for developers.
