We Hosted 100 Isolated Drupal Sites on One EKS Cluster — Here's Every Problem We Hit

We Hosted 100 Isolated Drupal Sites on One EKS Cluster — Here's Every Problem We Hit The goal was straightforward on paper: run roughly 100 isolated Drupal websites on a single Amazon EKS cluster. One cluster to rule them all, with each tenant completely isolated from the others — separate namespaces, separate databases, separate secrets, separate network policies. No shared anything that could become a blast radius. We started with three sites to validate every fundamental before scaling. This article is the honest account of what we built, why we made each decision, and — most valuably — the ten real problems we ran into and how we solved them. The Architecture in One Picture graph TD Internet --> R53[Route 53] R53 --> ALB[Shared ALB\nAWS Load Balancer Controller] ALB --> NS_A[drupal-site-alpha\nNamespace] ALB --> NS_B[drupal-site-beta\nNamespace] ALB --> NS_C[drupal-site-client\nNamespace] NS_A --> D_A[Drupal Pod] NS_A --> DB_A[Percona MySQL\nStatefulSet] NS_A --> ESO_A[ExternalSecr