How to use Vcluster to implement multi-tenancy in Kubernetes

Kubernetes revolutionizes the way organizations deploy and manage containerized applications, making it easier to orchestrate and scale applications across clusters. However, running multiple heterogeneous workloads on a shared Kubernetes cluster brings challenges such as resource contention, security risks, lack of customization, and complex management.

There are several ways to achieve isolation and multi-tenancy in Kubernetes:

• Kubernetes namespace: Namespace achieves certain isolation by dividing cluster resources between different users. However, namespaces share the same physical infrastructure and kernel resources. Therefore, isolation and customization are limited.
• Kubernetes distributions: Popular Kubernetes distributions such as Red Hat OpenShift and Rancher support Vcluster. They more effectively utilize Kubernetes' native features such as namespaces, RBAC, and network policies. Other benefits include a centralized control platform, pre-configured cluster templates and easy-to-use management.
• Hierarchical namespaces: In a traditional Kubernetes cluster, each namespace is independent. This means that users and applications in one namespace cannot access resources in another namespace unless they have explicit permissions. Hierarchical namespaces solve this problem by allowing parent-child relationships to be defined between namespaces. This means that a user or application that has permissions in the parent namespace will automatically have permissions in all child namespaces. This makes it much easier to manage permissions across multiple namespaces.
• Vcluster Project: The Vcluster project solves these pain points by partitioning a physical Kubernetes cluster into multiple independent software-defined clusters. Vcluster allows organizations to provide dedicated Kubernetes environments with guaranteed resources, security policies, and custom configurations for development teams, applications, and customers. This article will take an in-depth look at Vcluster, its capabilities, different implementation options, use cases and challenges. It will also examine best practices for maximizing utilization and simplifying Vcluster management.

1. What is Vcluster?

Vcluster is an open source tool that allows users to create and manage virtual Kubernetes clusters. A virtual Kubernetes cluster is a fully functional Kubernetes cluster that runs on top of another Kubernetes cluster. Vcluster works by creating a Vcluster in the namespace of the underlying Kubernetes cluster. Vcluster has its own control platform, but it shares the underlying cluster's worker nodes and network. This makes Vcluster a lightweight solution that can be deployed on any Kubernetes cluster.

When users create a Vcluster, they can specify the number of worker nodes they want the Vcluster to have. The Vcluster command line will then create the Vcluster and start the control platform pod on the worker node. The workload can then be deployed to the Vcluster using the kubectl CLI.

Users can learn more about Vcluster on the Vcluster website.

2. Benefits of using Vcluster

(1) Resource isolation

Vcluster allows users to allocate a portion of a central cluster's resources (such as CPU, memory, and storage) to a single Vcluster. This prevents the "noisy neighbor" problem when multiple teams share the same physical cluster. You can ensure that critical workloads get the resources they need without interruption.

(2)Access control

Using Vcluster, access policies can be enforced at the Vcluster level to ensure that only authorized users have access. For example, sensitive workloads like financial applications can run in isolated Vclusters. Restricting access is much simpler than namespace-level policies.

(3) Customization

Vcluster allows for extensive customization to the needs of individual teams, and can be customized with different Kubernetes versions, network policies, entry rules, and resource quotas. Developers can modify their Vclusters without affecting others.

(4)Multi-tenancy

Organizations must often provide Kubernetes access to multiple internal teams or external customers. Vcluster makes multi-tenancy easy to implement by creating independent, isolated environments within the same physical cluster.

(5) Easy to expand

Additional Vclusters can be quickly spun up or shut down to handle dynamic workloads and scaling needs. New development and test environments can be provisioned immediately without scaling out the entire physical cluster.

3. Workload isolation method before Vcluster

Before Vcluster emerged as a solution, organizations had leveraged various Kubernetes native features to achieve some workload isolation:

• Namespaces: Namespaces isolate cluster resources between different teams or applications. They provide basic isolation through resource quotas and network policies. However, there is no hypervisor-level isolation.
• Network policies: Fine-grained network policies restrict communication between pods and namespaces. This creates network segmentation between workloads. However, resource contention may still occur.
• Taints and tolerances: Applying a taint to a node prevents specified pods from being scheduled on the node. The pod must have a tolerance that matches the taint. This limits pods to specific nodes.
• Cloud virtual networks: On public clouds, using multiple virtual networks helps isolate Kubernetes cluster traffic. But pods in the cluster can still communicate.
• Third-party network plug-ins: CNI plug-ins like Calico, Weave, and Cilium can build overlay networks and fine-grained network policies to isolate traffic.
• Custom Controllers: Developing custom Kubernetes controllers allows for programmatic isolation of resources. But this requires a lot of programming expertise.

4. Demonstration of Vcluster

(1) Install Vcluster command line

Require:

• kubectl (check via kubectl version)
• helm v3 (check helm version)
• A working kube-context with access to the Kubernetes cluster (querying the namespace via kubectl).

Download the Vcluster CLI binary for arm64 based Ubuntu machines using the following command:

curl -L -o vcluster 
"https：//github.com/loft-sh/vcluster/releases/latest/download/vcluster-linux-arm64" && sudo install -c -m 0755 cluste /usr/local/bin && rm -f vcluster
bash

To confirm that the Vcluster CLI was installed successfully, test by:

vcluster --version
bash

To install on other servers, you can refer to the link below. Install Vcluster command line.

(2) Deploy Vcluster

Create a Vclustermy-first-Vcluster

vcluster create my-first-vcluster
bash

(3) Connect to Vcluster

Enter the following command to connect to Vcluster:

vcluster connect my-first-vcluster
bash

Use the kubectl command to get the namespace in the connected Vcluster.

kubectl get namespaces
bash

5. Deploy the application to Vcluster

Now, deploy a sample Nginx deployment in Vcluster. Create a deployment:

kubectl create namespace demo-nginx
kubectl create deployment nginx-deployment -n demo-nginx --image=nginx
bash

This will isolate the application in a namespace demo-nginx within Vcluster.

You can check if this demo deployment creates pods in Vcluster:

kubectl get pods -n demo-nginx
bash

6. Check the host cluster deployment

Now that the deployment in the Vcluster has been confirmed, now try to check the deployment in the host cluster.

Disconnect from Vcluster.

vcluster disconnect
bash

This will move the kube scene back to the host cluster. Now check if there is an available deployment in the host cluster.

kubectl get deployments -n vcluster-my-first-vcluster
bash

No resources found in Vcluster-my-Vcluster namespace. This is because the deployment is isolated in a Vcluster that is not accessible from other clusters.

Now use the following command to check if any pods are running in all namespaces.

kubectl get pods -n vcluster-my-first-vcluster
bash

You can now see the Nginx container running in the Vcluster namespace.

7. Vcluster use cases

Vcluster supports several important use cases by providing an isolated and customizable Kubernetes environment within a single physical cluster. Some of these are explored in more detail below:

(1) Development and testing environment

Assigning dedicated Vclusters to development teams allows them full control over configuration without impacting production workloads or other developers. Development teams can customize their Vclusters with the desired Kubernetes version, network policies, resource quotas, and access controls. Development teams can quickly spin up and shut down Vclusters to test different configurations. Because Vclusters provide guaranteed compute and storage resources, developers do not need to compete, nor do they impact the performance of applications running in other Vclusters.

(2) Production application isolation

Enterprise applications such as ERP, CRM and financial systems require predictable performance, high availability and tight security. Dedicated Vclusters allow these production workloads to be unaffected by other applications. Mission-critical applications can be allocated reserved capacity to avoid resource contention. Customized network policies ensure isolation. Clustering also allows for granular role-based access control to meet compliance needs. Rather than over-provisioning large clusters to avoid disruption, Vcluster provides guaranteed resources at a lower cost.

(3) Multi-tenant

Service providers and enterprises with multiple business units often need to securely provide Kubernetes access to different internal teams or external customers. Vcluster simplifies multi-tenancy by creating a separate self-service environment for each tenant and applying appropriate resource restrictions and access policies. Providers can easily serve new customers by adopting additional Vclusters. This eliminates the "noisy neighbor" problem and enables high-density workloads by packaging Vclusters based on actual usage, rather than peak demand.

(4) Compliance

Highly regulated industries such as finance and healthcare have stringent security and compliance requirements around data privacy, geolocation and access control. Dedicated Vclusters with internal network segmentation, role-based access control, and resource isolation make it easier to securely host compatible workloads with other applications in the same cluster.

(5) Temporary resources

Vcluster allows for immediate spin-up of ad hoc Kubernetes environments to handle the following use cases:

• Test cluster upgrades : New Kubernetes versions can be deployed to lower environments without downtime or impact to production.
• Evaluate new applications : Applications can be deployed into disposable Vclusters instead of shared development clusters to prevent conflicts.
• Capacity spikes : The new Vcluster provides burst capacity for traffic spikes instead of over-provisioning the entire cluster.
• Special events : Vclusters can be created temporarily for seminars, conferences and other events.

These Vclusters can simply be deleted once they are no longer needed without leaving a persistent footprint on the cluster.

(6) Workload integration

As organizations expand their Kubernetes footprint, there is a need to consolidate multiple clusters onto shared infrastructure without disrupting existing applications. Migrating applications to Vcluster provides logical isolation and customization, allowing them to run seamlessly with other workloads. This improves utilization and reduces operational overhead. Vcluster allows enterprise IT to provide a consistent Kubernetes platform across the entire organization while maintaining isolation. In summary, Vcluster is an important tool for optimizing Kubernetes environments through workload isolation, customization, security, and density. Use cases highlight how they can benefit a variety of needs within an organization, from developers to operations to business units.

8. Challenges of using Vcluster

While bringing significant benefits, there are some drawbacks to weigh:

(1) Complexity

Managing multiple Vclusters (albeit smaller ones) incurs more operational overhead than a single large Kubernetes cluster. Other tasks include:

• Provision and configure multiple control platforms.
• Apply security policies and access controls consistently across Vclusters.
• Monitoring and logging between Vclusters.
• Maintain designated resources and capacity for each Vcluster.

For example, cluster administrators must configure and update RBAC policies across 20 Vclusters instead of a single cluster. This requires more effort than centralized management of a single cluster. Static IP addresses and ports on Kubernetes can cause conflicts or errors.

(2) Resource allocation and management

Balancing a Vcluster's resource consumption and performance can be tricky, as they may have different needs or expectations.

For example, a Vcluster may need to scale up or down based on workload, or share resources with other Vclusters or namespaces. Vcluster sizes with peak application demand may have excess unused capacity during non-peak periods that sits idle and cannot be utilized by other Vclusters.

(3) Limited customization

The ability to customize Vclusters varies by implementation. Namespaces provide the least flexibility, while the cluster API provides the most flexibility. Tools like OpenShift balance customization with simplicity. For example, namespaces cannot run different Kubernetes versions or network plugins. The Cluster API allows full customization, but is more complex.

9. Conclusion

Vcluster enables Kubernetes users to customize, isolate and scale workloads across shared physical clusters. Vcluster provides strong technical isolation by allocating dedicated control plane resources and access policies. For use cases like multi-tenancy, Vcluster provides simpler and more secure Kubernetes management.

Vcluster can also be used to reduce the cost overhead of Kubernetes and can be used in staging environments. Tools like OpenShift, Rancher, and the Kubernetes Cluster API make deploying and managing Vcluster easier. As adoption increases, you can expect more innovation in the Vcluster space to further streamline operations and maximize utilization. While Vcluster has some drawbacks, for many organizations the benefits clearly outweigh the added complexity.

10. Developer tools supporting Kubernetes deployment

Low-code development is a trend that has attracted much attention in the field of web development in recent years. Low-code development refers to using minimal programming code to develop applications or business logic, which allows even beginners with no IT or programming experience to quickly create the desired functionality.

Although low-code development has not yet threatened the role of traditional developers, it is undeniable that the trend is moving toward low-code (or no-code) development. According to the prediction of American research company Gartner, by 2024, about 65% of application development projects will be developed through low-code platforms. This trend cannot be ignored by developers, and it is expected that the way developers work will gradually change in the next few years.

There are many low-code platforms on the market. The JNPF development platform is a full-stack development platform based on SpringBoot+Vue3. It adopts microservices, front-end and back-end separation architecture, and is built quickly based on visual process modeling, form modeling, and report modeling tools. For business applications, the platform can be deployed locally and also supports K8S deployment.

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The engine-based software rapid development model, in addition to the above functions, is also equipped with visualization function engines such as chart engine, interface engine, portal engine, organization user engine, etc., to basically realize the visual construction of page UI. There are hundreds of built-in functional controls and usage templates, which can meet the user's personalized needs to the greatest extent with simple drag-and-drop operations. Since the functions of the JNPF platform are relatively complete, this article chooses this tool to expand, so that you can more intuitively see the advantages of low code .