Several teams will share one Kubernetes cluster. How would you isolate tenants and secure the cluster?

What the interviewer wants to hear

• Namespace per team with RBAC least privilege bound to SSO groups
• Default-deny NetworkPolicies with explicit allows
• Resource quotas and limit ranges to stop noisy neighbours
• Pod Security Standards restricted and admission policies
• Workload identity per service; secrets from a secret manager
• Audit logging and runtime detection; separate clusters for hard isolation

Model answer

Each team gets its own namespaces, created from a template that sets RBAC, quotas and policies, so isolation is consistent. Access comes from SSO groups bound to namespace-scoped roles; nobody but the platform team has cluster-admin, and CI deploys with narrow service accounts. Every namespace starts with default-deny NetworkPolicies, and teams add explicit allow rules, enforced by a CNI such as Cilium or Calico. ResourceQuotas and LimitRanges stop one team from starving others. Pod Security Admission at the restricted level blocks privileged containers, host mounts and root users, and an admission controller like Kyverno enforces extra rules such as signed images from approved registries and required labels. Workloads use workload identity for cloud access, and secrets come from a secret manager via the External Secrets Operator. I enable API audit logs and runtime detection with a tool like Falco. For tenants that need strong isolation, such as untrusted code or strict compliance, I would use separate clusters or virtual clusters instead.

More hard DevOps Engineer questions

• You are asked to build an internal platform so 30 product teams can deploy services to Kubernetes on their own. How would you design it?
• How would you secure the software supply chain from source code to a running container in production?
• Your company wants to run a critical service active-active in two cloud regions. What are the main DevOps challenges and how would you handle them?
• Your DORA metrics show a 30% change failure rate and long recovery times. How would you bring them down without slowing teams down?
• How do you plan and carry out a Kubernetes version upgrade for production clusters with minimal risk?
• Leadership asks you to cut the cloud bill for your Kubernetes platform by 30 percent without hurting reliability. How do you approach it?
• You are the incident commander for a major outage affecting all customers. Describe how you run the incident from first page to postmortem.
• Design CI/CD for a monorepo with 60 services and 200 engineers where full builds take over an hour.
• Design a disaster recovery plan for a platform whose business requires an RTO of 1 hour and an RPO of 5 minutes for the loss of a whole cloud region.