In this paper, we overview the design and implementation of a new approach to Application Performance Monitoring (APM) for Cloud Platforms-as-a-service (PaaS). Our approach couples and integrates full stack performance monitoring and analysis into the PaaS system itself for comprehensive introspection. To enable this, we employ lightweight and intelligent sensors and agents and "pluggable" data analysis modules that facilitate service level objectives (SLOs) for application response time, application-specific performance anomaly detection and root cause analysis, and workload change point detection. We implement our APM by combining the popular Elastic Stack with other common PaaS services in a way that is portable so that it can be integrated easily into public and private PaaS systems.