Add README.md (#24)

Author: jkroepke

docs/Grafana.md

@@ -0,0 +1,44 @@
+# Grafana Integration
+
+This guide explains how to visualize access-log-exporter metrics in Grafana.
+
+## Quick Setup
+
+### 1. Import Dashboard
+
+access-log-exporter includes a pre-built Grafana dashboard for visualizing web server metrics.
+
+**Import the dashboard:**
+
+1. Download the dashboard JSON: [grafana-dashboard.json](https://github.com/jkroepke/access-log-exporter/blob/main/contrib/grafana-dashboard.json)
+2. In Grafana, go to **Dashboards** → **Import**
+3. Upload the JSON file or paste the content
+4. Click **Import**
+
+### 2. Dashboard Features
+
+The included dashboard provides:
+
+- **Request Rate**: Requests per second by host and status
+- **Response Times**: P50, P95, P99 response time percentiles
+- **Error Rates**: 4xx and 5xx error percentages
+- **Traffic Volume**: Request/response size metrics
+- **Upstream Performance**: Connection and response times (for upstream presets)
+- **URI Analytics**: Top endpoints by traffic (for `simple_uri_upstream` preset)
+
+## Demo Setup
+
+For a complete demo environment with Grafana, see the demo configuration in `docs/demo/`:
+
+```bash
+cd docs/demo
+docker-compose up -d
+```
+
+This starts:
+- access-log-exporter on port 4040
+- Nginx with sample traffic on port 8080
+- Prometheus on port 9090
+- Grafana on port 3000
+
+The dashboard will be automatically imported and configured.

docs/Home.md

@@ -7,3 +7,5 @@ Welcome to the access-log-exporter wiki!
 1. [Installation](Installation)
 2. [Configuration](Configuration)
 3. [Webserver Configuration](Webserver)
+4. [Prometheus](Prometheus)
+4. [Grafana](Grafana)

docs/Prometheus.md

@@ -0,0 +1,87 @@
+# Prometheus Integration
+
+This guide explains how to integrate access-log-exporter with Prometheus.
+
+## Quick Setup
+
+### 1. Start access-log-exporter
+
+```bash
+access-log-exporter --preset simple
+```
+
+By default, metrics are exposed on `http://localhost:4040/metrics`
+
+### 2. Configure Prometheus
+
+Add this to your `prometheus.yml`:
+
+```yaml
+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:
+
+```prometheus
+http_requests_total{host="example.com",method="GET",status="200",path="/api/users/.+"}
+```
+
+## Useful Queries
+
+```promql
+# 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
+
+```yaml
+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

internal/nginx/collector.go

@@ -1,12 +1,14 @@
 package nginx
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"log/slog"
 	"net/http"
 	"strings"
 	"sync"
+	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 )
@@ -105,15 +107,30 @@ func (c *Collector) Describe(ch chan<- *prometheus.Desc) {
 }
 
 func (c *Collector) Collect(ch chan<- prometheus.Metric) {
-	c.logger.Error("hit Collect method")
-
 	c.mu.Lock() // To protect metrics from concurrent collects
 	defer c.mu.Unlock()
 
 	serverVersion := "N/A"
 
-	//nolint:noctx
-	resp, err := http.Get(c.scrapeURL)
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.scrapeURL, nil)
+	if err != nil {
+		c.logger.Error("Failed to create HTTP request for NGINX metrics",
+			slog.String("url", c.scrapeURL),
+			slog.Any("error", err),
+		)
+
+		ch <- prometheus.MustNewConstMetric(c.upMetric,
+			prometheus.GaugeValue, 0, serverVersion)
+
+		return
+	}
+
+	req.Header.Set("User-Agent", "jkroepke/access-log-exporter")
+
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		c.logger.Error("Failed to scrape NGINX metrics",
 			slog.String("url", c.scrapeURL),