Prometheus

This guide explains how to integrate access-log-exporter with Prometheus.

Quick Setup

1. Start access-log-exporter

access-log-exporter --preset simple

By default, metrics are exposed on http://localhost:4040/metrics

2. Configure Prometheus

Add this to your prometheus.yml:

scrape_configs:
  - job_name: 'access-log-exporter'
    static_configs:
      - targets: ['localhost:4040']
    scrape_interval: 30s

3. Verify

Check Prometheus targets at http://your-prometheus:9090/targets

Available Metrics

Basic Metrics (simple preset)

• http_requests_total - Request counter with labels: host, method, status
• http_request_duration_seconds - Response time histogram
• http_request_size_bytes - Request size histogram
• http_response_size_bytes - Response size histogram

Upstream Metrics (simple_upstream preset)

• http_upstream_connect_duration_seconds - Upstream connection time
• http_upstream_header_duration_seconds - Upstream header time
• http_upstream_request_duration_seconds - Upstream response time

URI Tracking (simple_uri_upstream preset)

All metrics include request_uri label with path normalization:

http_requests_total{host="example.com",method="GET",status="200",path="/api/users/.+"}

Useful Queries

# Requests per second
rate(http_requests_total[5m])

# 95th percentile response time
histogram_quantile(0.95, rate(http_request_duration_seconds_bucket[5m]))

# Error rate
sum(rate(http_requests_total{status=~"5.."}[5m])) / sum(rate(http_requests_total[5m]))

Docker Compose Example

version: '3.8'
services:
  access-log-exporter:
    image: ghcr.io/jkroepke/access-log-exporter:latest
    ports:
      - "4040:4040"
      - "8514:8514/udp"

  prometheus:
    image: prom/prometheus:latest
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml

Troubleshooting

• No metrics: Check if access-log-exporter is receiving logs from your web server
• High cardinality: Use simple_uri_upstream preset for automatic path normalization
• Performance: Use 30-60 second scrape intervals for web metrics