Module endpoint

adaptive_pipeline::infrastructure::metrics

Module endpoint 

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§Metrics Endpoint HTTP Server

This module provides a lightweight HTTP server for exposing Prometheus metrics and health check endpoints. It serves as the interface between the internal metrics collection system and external monitoring tools.

§Overview

The metrics endpoint provides:

  • Prometheus Metrics: Exposes metrics in Prometheus format at /metrics
  • Health Checks: Provides health status at /health endpoint
  • Lightweight Server: Minimal HTTP server with low resource overhead
  • Concurrent Handling: Handles multiple concurrent metric requests
  • Error Resilience: Graceful error handling and recovery

§Architecture

The endpoint follows these design principles:

  • Single Purpose: Dedicated to metrics and health check serving
  • Async Processing: Non-blocking request handling using Tokio
  • Resource Efficient: Minimal memory and CPU overhead
  • Standards Compliant: Follows Prometheus metrics format standards

§Endpoints

§/metrics - Prometheus Metrics

Returns metrics in Prometheus text format:

  • Content-Type: text/plain; version=0.0.4; charset=utf-8
  • Format: Prometheus exposition format
  • Compression: Optional gzip compression support
  • Caching: Metrics are generated fresh on each request

§/health - Health Check

Returns simple health status:

  • Content-Type: text/plain
  • Response: “OK” for healthy status
  • Status Code: 200 for healthy, 500 for unhealthy
  • Latency: Low-latency response for monitoring systems

§Usage Examples

§Starting the Metrics Server

§Accessing Metrics

# Get Prometheus metrics
curl http://localhost:9090/metrics

# Check health status
curl http://localhost:9090/health

§Configuration

The server configuration is managed through the ConfigService:

  • Port: Configurable listening port (default: 9090)
  • Bind Address: Currently binds to localhost only
  • Request Timeout: Configurable request timeout
  • Connection Limits: Configurable concurrent connection limits

§Performance Characteristics

  • Throughput: Handles hundreds of requests per second
  • Latency: Sub-millisecond response times for health checks
  • Memory Usage: Minimal memory footprint (~1-2 MB)
  • CPU Usage: Low CPU overhead during normal operation

§Error Handling

The server handles various error conditions:

  • Metrics Generation Errors: Returns 500 with error message
  • Connection Errors: Logged and connection dropped
  • Parse Errors: Returns 400 for malformed requests
  • Resource Exhaustion: Graceful degradation under load

§Security Considerations

  • Local Binding: Server binds to localhost only by default
  • No Authentication: Metrics endpoint has no built-in authentication
  • Rate Limiting: No built-in rate limiting (should be handled externally)
  • Information Disclosure: Metrics may contain sensitive operational data

§Integration

Integrates with:

  • Prometheus: Primary metrics collection system
  • Grafana: Visualization and dashboarding
  • AlertManager: Alerting based on metrics
  • Load Balancers: Health check integration
  • Monitoring Tools: Various monitoring and observability tools

Structs§

MetricsEndpoint
Lightweight HTTP server for exposing Prometheus metrics and health check endpoints.