As blockchain technologies are increasingly adopted in enterprise and research domains, the need for secure, scalable, and performance-transparent node infrastructure has become critical. While self-hosted Ethereum nodes offer operational control, they often lack elasticity and require complex maintenance. This paper presents a hybrid, service-oriented architecture for deploying and monitoring Ethereum full nodes using Amazon Managed Blockchain (AMB), integrated with EC2-based telemetry, IAM-enforced security policies, and reproducible automation via the AWS Cloud Development Kit (CDK). Our architecture supports end-to-end observability through custom EC2 scripts leveraging Web3.py and JSON-RPC, collecting over 1,000 real-time data points—including gas utilization, transaction inclusion latency, and mempool dynamics. These metrics are visualized and monitored through AWS CloudWatch, enabling service-level performance tracking and anomaly detection. This cloud-native framework restores low-level observability lost in managed environments, without sacrificing the scalability and convenience of managed services. By bridging the operational simplicity of managed blockchain services with the transparency and flexibility required for protocol research and enterprise-grade monitoring, this work delivers one of the first reproducible, performance-instrumented Ethereum deployments on AMB. The proposed architecture serves as a blueprint for secure, observable, and service-oriented blockchain infrastructure, supporting both research experimentation and production use.