Multi-Tenancy in K8s & OpenShift #8 - Ingress Isolation for External Access

In this series, we've covered key aspects like Namespace-Based Isolation, Network Policies, RBAC, Resource Quotas, LimitRanges, and Pod Security Standards (PSS) to ensure secure and fair resource management in multi-tenant Kubernetes clusters. In our previous blog, we discussed Storage Isolation for Persistent Volume Security, emphasizing the importance of securing persistent storage to protect tenant data and maintain data integrity in a multi-tenant setup.

Now, in a multi-tenant Kubernetes environment, managing external access to each tenant’s applications is essential for maintaining security and isolation. Ingress Control enables you to manage and segregate external access, ensuring each tenant can expose their services to the internet without impacting other tenants. By defining isolated ingress rules, you can enforce external access segregation, providing tailored access controls that align with the unique requirements of each tenant.

Multi-Tenancy in Kubernetes & Openshift: A Comprehensive Guide

Part 1: Use Cases & Implementations

Part 2: Namespace-Based Isolation for Workload Separation

Part 3: Network Policies for Network Isolation

Part 4: Role-Based Access Control (RBAC) for Authorization

Part 5: Resource Quotas and LimitRanges for Resource Control

Part 6: Pod Security Standards (PSS) for Workload Security

Part 7: Storage Isolation for Persistent Volume Security

Part 8: Ingress Control Isolation for External Access Segregation

Part 9: Control Plane Robustness to Safeguard shared Kubernetes Resources

Part 10: NodePort and HostPort Restrictions for Enhanced Network Security

Part 11: Resource and Cost Tracking for ShowBack/ChargeBack

Part 12: Multi-Tenant Considerations for Shared Tools

Ingress Control Isolation for External Access Segregation

What Is Ingress in Kubernetes?

An Ingress is an API object that manages external access to services within a Kubernetes cluster, typically for HTTP/HTTPS traffic. Ingress resources define routing rules and path-based access to services, allowing you to expose applications to the internet. In a multi-tenant environment, Ingress Controllers enforce these rules, directing incoming traffic based on hostnames, paths, or tenant-specific criteria.

Why Use Ingress Control in Multi-Tenancy?

In a multi-tenant setup, tenants need secure and isolated external access to their applications. Without proper ingress controls, you might face challenges such as:

• Cross-tenant traffic exposure: Without isolation, tenants could unintentionally expose their applications to others, creating security risks.

• Domain and hostname conflicts: Tenants may accidentally use overlapping hostnames, causing routing conflicts and misdirected traffic.

• Interference and security vulnerabilities: Shared ingress without proper isolation could allow malicious tenants to exploit others' applications, bypassing intended security measures.

By implementing ingress control, you can define and manage external access for each tenant, ensuring it meets the specific security and operational requirements of their applications.

How Ingress Control Works in Kubernetes

Ingress resources define how external traffic should be routed to services within a Kubernetes cluster. With host- and path-based routing, you can direct traffic to the appropriate tenant’s services. Here are the main components involved in ingress control:

• Ingress Resources: Define rules for routing external traffic to services based on hostnames and paths.

• Ingress Controllers: Implement the routing rules set by Ingress resources. Popular Ingress controllers include NGINX, Traefik, and Istio.

For multi-tenancy, you can use tenant-specific Ingress resources along with the right network policies and TLS certificates to ensure secure and isolated access.

Use Cases for Ingress Control in Multi-Tenancy

• Isolating Tenant Domains: Each tenant can have its own subdomain, ensuring that access remains isolated. For example, tenant1.example.com and tenant2.example.com will route traffic independently, avoiding any conflicts.

• Restricting Path-Based Access: Path-based routing helps control which parts of an application are externally accessible. For example, /public might be exposed, while /admin is restricted to internal access.

• Enforcing Secure Communication: By configuring TLS per tenant, you ensure encrypted traffic between users and the application, meeting best practices for secure communication.

Best Practices for Ingress Control Isolation

• Use Unique Subdomains per Tenant: Assign a unique hostname or subdomain for each tenant to avoid routing conflicts and ensure isolated access for each tenant.

• Enforce TLS for All Ingresses: Make sure that all Ingress resources are configured with TLS to encrypt external traffic, ensuring secure communication for tenant applications.

• Combine Ingress with Network Policies: Limit access to only the services that need to be exposed by integrating Ingress with network policies. This helps control traffic within the cluster and complements the external access segregation provided by Ingress.

• Monitor Ingress Traffic: Use monitoring tools to track ingress traffic patterns. This enables you to detect potential misuse or abnormal traffic spikes for specific tenants, allowing proactive measures to prevent security issues.

Conclusion

Ingress Control plays a critical role in securely managing external access in a multi-tenant Kubernetes environment. By setting up tenant-specific ingress rules, using unique subdomains, and enforcing TLS encryption, you can offer secure and isolated access for each tenant’s applications. This approach not only enhances security but also ensures efficient and reliable traffic routing, helping you maintain a robust and compliant multi-tenant Kubernetes infrastructure.

Simplifying Multi-Tenancy with Stakater Multi-Tenant Operator

Implementing multi-tenancy in Kubernetes can be complex. It requires a deep understanding of Kubernetes and involves configuring elements like namespace isolation, network policies, RBAC, and resource quotas. Achieving a secure and efficient setup demands significant time and effort. This is where the Stakater Multi-Tenant Operator (MTO) shines.

The Stakater Multi-Tenant Operator simplifies and accelerates the process of implementing multi-tenancy in Kubernetes clusters. It provides a powerful, automated framework for managing tenants, enabling organizations to quickly establish secure, isolated, and well-organized environments. By using MTO, businesses can ensure controlled external access for each tenant, addressing the specific security and operational needs of every tenant. This enhances the overall effectiveness and efficiency of their multi-tenant architecture.

In our next blog, we’ll explore how to strengthen the control plane to safeguard shared Kubernetes resources, focusing on strategies to enhance stability and security in multi-tenant environments.