Add prometheus exporter on :9100

cmd/collector/prom_test.go

@@ -0,0 +1,130 @@
+package main
+
+import (
+	"net/http/httptest"
+	"strings"
+	"testing"
+)
+
+func TestPromStoreIngestBodyBuckets(t *testing.T) {
+	ps := NewPromStore()
+	// 512 bytes: > 256, ≤ 1024 → bucket[0] stays 0, buckets[1..N] get 1
+	ps.Ingest(LogRecord{Website: "example.com", Method: "GET", Status: "200", BodyBytesSent: 512})
+
+	ps.mu.Lock()
+	be := ps.body["example.com"]
+	ps.mu.Unlock()
+
+	if be == nil {
+		t.Fatal("expected body entry, got nil")
+	}
+	if be.buckets[0] != 0 { // le=256: 512 > 256
+		t.Errorf("le=256 bucket = %d, want 0", be.buckets[0])
+	}
+	if be.buckets[1] != 1 { // le=1024: 512 ≤ 1024
+		t.Errorf("le=1024 bucket = %d, want 1", be.buckets[1])
+	}
+	for i := 2; i <= promNumBodyBounds; i++ {
+		if be.buckets[i] != 1 {
+			t.Errorf("bucket[%d] = %d, want 1", i, be.buckets[i])
+		}
+	}
+	if be.sum != 512 {
+		t.Errorf("sum = %d, want 512", be.sum)
+	}
+}
+
+func TestPromStoreIngestTimeBuckets(t *testing.T) {
+	ps := NewPromStore()
+	// 0.075s: > 0.05, ≤ 0.1
+	ps.Ingest(LogRecord{Website: "example.com", Method: "GET", Status: "200", RequestTime: 0.075})
+
+	ps.mu.Lock()
+	te := ps.reqTime["example.com"]
+	ps.mu.Unlock()
+
+	if te == nil {
+		t.Fatal("expected time entry, got nil")
+	}
+	// le=0.05 (index 3): 0.075 > 0.05 → 0
+	if te.buckets[3] != 0 {
+		t.Errorf("le=0.05 bucket = %d, want 0", te.buckets[3])
+	}
+	// le=0.1 (index 4): 0.075 ≤ 0.1 → 1
+	if te.buckets[4] != 1 {
+		t.Errorf("le=0.1 bucket = %d, want 1", te.buckets[4])
+	}
+	// +Inf (last): always 1
+	if te.buckets[promNumTimeBounds] != 1 {
+		t.Errorf("+Inf bucket = %d, want 1", te.buckets[promNumTimeBounds])
+	}
+}
+
+func TestPromStoreCounter(t *testing.T) {
+	ps := NewPromStore()
+	ps.Ingest(LogRecord{Website: "a.com", Method: "GET", Status: "200"})
+	ps.Ingest(LogRecord{Website: "a.com", Method: "GET", Status: "200"})
+	ps.Ingest(LogRecord{Website: "a.com", Method: "POST", Status: "201"})
+
+	ps.mu.Lock()
+	c1 := ps.counters[promCounterKey{"a.com", "GET", "200"}]
+	c2 := ps.counters[promCounterKey{"a.com", "POST", "201"}]
+	ps.mu.Unlock()
+
+	if c1 != 2 {
+		t.Errorf("GET/200 count = %d, want 2", c1)
+	}
+	if c2 != 1 {
+		t.Errorf("POST/201 count = %d, want 1", c2)
+	}
+}
+
+func TestPromStoreServeHTTP(t *testing.T) {
+	ps := NewPromStore()
+	ps.Ingest(LogRecord{
+		Website: "example.com", Method: "GET", Status: "200",
+		BodyBytesSent: 100, RequestTime: 0.042,
+	})
+
+	req := httptest.NewRequest("GET", "/metrics", nil)
+	rec := httptest.NewRecorder()
+	ps.ServeHTTP(rec, req)
+
+	body := rec.Body.String()
+
+	checks := []string{
+		"# TYPE nginx_http_requests_total counter",
+		`nginx_http_requests_total{host="example.com",method="GET",status="200"} 1`,
+		"# TYPE nginx_http_response_body_bytes histogram",
+		`nginx_http_response_body_bytes_bucket{host="example.com",le="256"} 1`, // 100 ≤ 256
+		`nginx_http_response_body_bytes_count{host="example.com"} 1`,
+		`nginx_http_response_body_bytes_sum{host="example.com"} 100`,
+		"# TYPE nginx_http_request_duration_seconds histogram",
+		`nginx_http_request_duration_seconds_bucket{host="example.com",le="0.05"} 1`, // 0.042 ≤ 0.05
+		`nginx_http_request_duration_seconds_count{host="example.com"} 1`,
+	}
+	for _, want := range checks {
+		if !strings.Contains(body, want) {
+			t.Errorf("missing %q in output:\n%s", want, body)
+		}
+	}
+}
+
+func TestPromStoreCounterCap(t *testing.T) {
+	ps := NewPromStore()
+	// Fill to cap with distinct {host,method,status} combos
+	for i := 0; i < promCounterCap+10; i++ {
+		host := strings.Repeat("x", i%10+1) + ".com"
+		status := "200"
+		if i%3 == 0 {
+			status = "404"
+		}
+		ps.Ingest(LogRecord{Website: host, Method: "GET", Status: status})
+	}
+	ps.mu.Lock()
+	n := len(ps.counters)
+	ps.mu.Unlock()
+	if n > promCounterCap {
+		t.Errorf("counter map size %d exceeds cap %d", n, promCounterCap)
+	}
+}