STCLab operates high-traffic SaaS platforms that require precise traffic management and bot mitigation. They handle millions of concurrent connections, making infrastructure stability vital. To manage this complexity, they use Istio, which acts as a control plane for Envoy proxies alongside their containers. Istio’s configurations—like VirtualService and AuthorizationPolicy—are critical for handling traffic efficiently. One key feature is the Proxy Protocol, which preserves the original client IP addresses, essential for accurate bot detection, especially in environments like AWS where IPs can be lost. Access control is another focus area for STCLab. They use AuthorizationPolicy to restrict access to internal APIs, ensuring that only designated office IPs can connect. For request routing, they implement query parameter-based methods to ensure that each tenant’s requests hit the same backend instance, maintaining consistency and allowing for easy troubleshooting. In cases where strict consistency isn't necessary, they switch to Consistent Hashing to route requests based on tenant IDs. Resilience is enhanced through Outlier Detection, which removes unhealthy pods to protect service availability. If a pod returns five consecutive 5xx errors, it gets ejected for at least 30 seconds, minimizing the impact of failures. During a deployment issue, this system reacted within 50 seconds, ensuring traffic was rerouted to healthy instances without manual intervention. They also emphasize the importance of graceful shutdown procedures for long-lived connections, ensuring no abrupt terminations disrupt active sessions during updates. The shutdown sequence is meticulously planned, allowing existing connections to drain properly. Operational best practices include starting simple with Istio's features, being cautious with telemetry to avoid overwhelming monitoring systems, and carefully managing EnvoyFilters due to their complexity. These strategies have proven effective in maintaining high performance and reliability as they scale their services.