Production-grade GCP GKE microservices architecture with Istio service mesh, multi-tier services (API, Auth, Data), and comprehensive observability. Traffic flows from Internet through Cloud Load Balancing and Cloud Armor WAF to an Ingress Controller, which routes to three independent microservices managed by Istio for traffic control and security policies. API, Auth, and Data services scale independently via HPA (2-10, 2-6, and 2-8 replicas) and connect to Cloud Memorystore Redis for caching and Cloud SQL PostgreSQL with read replicas for persistence. Cloud IAM, Cloud KMS, NetworkPolicy, and ServiceAccounts enforce least-privilege access, while Cloud Monitoring and Cloud Logging provide full observability across the cluster. Fork this diagram on Diagrams.so to customize node pools, add additional services, or adjust replica ranges for your workload. This architecture demonstrates GCP best practices for resilience, security, and cost optimization in containerized environments.