feat: Pass around one big global context

internal/metrics/metrics.go

@@ -0,0 +1,116 @@
+package metrics
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type LokiMetricConfig struct {
+	Url           string
+	BotUserAgents *[]regexp.Regexp
+	Enabled       bool
+}
+
+// Checks if we should send a metric ping to Loki based on the served path.
+func (c *LokiMetricConfig) ShouldSendMetrics(path, userAgent string) bool {
+	if !strings.HasSuffix(path, ".html") || !c.Enabled {
+		return false
+	}
+
+	// Filter out bots
+	for _, pattern := range *c.BotUserAgents {
+		if pattern.MatchString(userAgent) {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (c *LokiMetricConfig) SendMetricPing(domain, path, referrer string) {
+	msg := fmt.Sprintf("path=\"%s\" referrer=\"%s\"", path, referrer)
+	data := map[string]interface{}{
+		"streams": []map[string]interface{}{
+			{
+				"stream": map[string]string{
+					// Labels
+					"service": "rio",
+					"domain":  domain,
+					"type":    "metric",
+				},
+				"values": [][]interface{}{
+					{
+						strconv.Itoa(int(time.Now().UnixNano())),
+						msg,
+					},
+				},
+			},
+		},
+	}
+	jsonData, err := json.Marshal(data)
+	if err != nil {
+		log.Errorf("Failed to send metric ping to Loki: %v", err)
+		return
+	}
+
+	log.Debugf("Sending payload %s", string(jsonData))
+
+	// Send the ping to the Loki server
+	go func() {
+		res, err := http.Post(
+			c.Url,
+			"application/json",
+			strings.NewReader(string(jsonData)),
+		)
+		if err != nil {
+			log.Errorf("Failed to send payload to Loki: %v", err)
+			return
+		}
+
+		defer res.Body.Close()
+		if res.StatusCode != 204 {
+			log.Errorf("Loki returned non-204 status code %d", res.StatusCode)
+			body, err := ioutil.ReadAll(res.Body)
+			if err != nil {
+				log.Warnf("Failed to read body. No more specific error message")
+				return
+			}
+			log.Errorf("-> %s", body)
+		}
+	}()
+}
+
+// Reads a JSON array of bot user agents from disk and parses them
+// into regular expressions.
+func ReadBotPatterns(file string) ([]regexp.Regexp, error) {
+	content, err := ioutil.ReadFile(file)
+	if err != nil {
+		log.Warnf("Failed to read bot metrics file: %v", err)
+		return []regexp.Regexp{}, err
+	}
+
+	var payload []string
+	err = json.Unmarshal(content, &payload)
+	if err != nil {
+		log.Warnf("Failed to unmarshal file: %v", err)
+		return []regexp.Regexp{}, err
+	}
+
+	patterns := make([]regexp.Regexp, 0)
+	for _, v := range payload {
+		patterns = append(
+			patterns,
+			*regexp.MustCompile(v),
+		)
+	}
+
+	return patterns, nil
+}

internal/metrics/metrics_test.go

@@ -0,0 +1,24 @@
+package metrics
+
+import (
+	"regexp"
+	"testing"
+)
+
+func TestShouldPing(t *testing.T) {
+	cfg := LokiMetricConfig{
+		Enabled: true,
+		Url:     "",
+		BotUserAgents: &[]regexp.Regexp{
+			*regexp.MustCompile("random-bot/.*"),
+		},
+	}
+
+	if cfg.ShouldSendMetrics("/index.html", "random-bot/v23.5") {
+		t.Fatalf("Accepted bot user-agent")
+	}
+
+	if !cfg.ShouldSendMetrics("/index.html", "Firefox/...") {
+		t.Fatalf("Rejected real user-agent")
+	}
+}