Soft multitenancy is a model where multiple tenants share the same Kubernetes cluster and its control plane, with logical separation enforced by native Kubernetes objects like Namespaces, RBAC, ResourceQuotas, and NetworkPolicies. The primary advantage and reason for choosing this model is to maximize resource utilization and operational efficiency. By allowing tenants to share the underlying infrastructure (nodes, control plane, etc.), organizations can reduce overhead and costs. This approach is suitable when tenants are trusted, such as different teams within the same enterprise, and the main goal is resource management and sharing, rather than strict, security-focused isolation.

B. When the priority is enabling complete isolation between tenants.

This describes the primary goal of hard multitenancy, which uses physically or virtually separate infrastructure (e.g., dedicated clusters, nodes, or virtual control planes) to achieve strong isolation.

C. When the priority is enabling fine-grained control over tenant resources.

While soft multitenancy uses tools like ResourceQuotas for control, this is not its unique differentiator. Hard multitenancy can also offer fine-grained control, making this statement less precise.

D. When the priority is enabling strict security boundaries between tenants.

This is the main objective of hard multitenancy. Soft multitenancy provides logical boundaries that are not considered as secure or strict against malicious or compromised tenants.

1. Kubernetes Official Documentation

"Multi-tenancy": The documentation distinguishes between soft and hard multitenancy. It implicitly supports that soft multitenancy is for shared environments

stating

"In a soft multi-tenancy model

tenants are aware of each other

but are prevented from interfering with each other by policies... This is often used by different teams within an enterprise." This context of internal teams highlights the focus on shared

efficient resource usage over absolute isolation.

Source: Kubernetes Authors. (n.d.). Multi-tenancy. Kubernetes Documentation. Retrieved from https://kubernetes.io/docs/concepts/security/multi-tenancy/

2. CNCF Kubernetes Policy Working Group

"Multi-Tenancy in Kubernetes Whitepaper": This paper discusses the spectrum of multitenancy. It frames soft multitenancy (referred to as "Namespace as a Service") as a model that "provides a good balance between isolation and resource sharing

" emphasizing that the sharing aspect is a key characteristic.

Source: CNCF Kubernetes Policy Working Group. (2021). Kubernetes Policy Management White Paper. Section: "Multi-Tenancy". Available at https://github.com/cncf/tag-security/blob/main/whit epapers/policy/CNCF-Policy-WhitePaper-v1.pdf

3. Red Hat OpenShift Documentation (Official Vendor Documentation)

"About multitenancy": The documentation explains that multitenancy allows an administrator to "use the cluster for multiple applications

teams

and departments

which saves money on infrastructure and administration." This directly links the multitenancy concept

particularly the shared-cluster (soft) model

to efficiency and resource sharing.

Source: Red Hat. (n.d.). About multitenancy. OpenShift Container Platform 4.14 Documentation. Retrieved from https://docs.openshift.com/container-platform/4.14/multitenancy/about-multitenancy.html