Application Monitoring with Prometheus and Grafana: A Developer's Guide

You can't fix what you can't see. Monitoring tells you when things break, why they broke, and how to prevent it. Here's how to set it up properly. The Three Pillars of Observability Metrics: Numeric measurements over time (request count, latency, CPU usage) Logs: Discrete events with context (errors, warnings, audit trails) Traces: Request flow across services (distributed tracing) Adding Prometheus Metrics to Python pip install prometheus-client from prometheus_client import Counter , Histogram , Gauge , start_http_server import time # Define metrics REQUEST_COUNT = Counter ( ' http_requests_total ' , ' Total HTTP requests ' , [ ' method ' , ' endpoint ' , ' status ' ] ) REQUEST_LATENCY = Histogram ( ' http_request_duration_seconds ' , ' HTTP request latency ' , [ ' method ' , ' endpoint ' ], buckets = [ 0.01 , 0.05 , 0.1 , 0.25 , 0.5 , 1.0 , 2.5 , 5.0 ] ) ACTIVE_CONNECTIONS = Gauge ( ' active_connections ' , ' Number of active connections ' ) # Use in your app def handle_request ( me