feat(gotenberg): add telemetry attribute helpers for redaction and capping

pkg/gotenberg/attrs.go

@@ -0,0 +1,54 @@
+package gotenberg
+
+import (
+	"net/url"
+)
+
+// maxAttrRunes bounds the length of a string span attribute to keep payload
+// size and backend cardinality in check.
+const maxAttrRunes = 256
+
+// CapAttr truncates s to at most [maxAttrRunes] runes, appending an ellipsis
+// when it shortens the value. It is multibyte-safe.
+func CapAttr(s string) string {
+	runes := []rune(s)
+	if len(runes) <= maxAttrRunes {
+		return s
+	}
+	return string(runes[:maxAttrRunes-1]) + "…"
+}
+
+// RedactURL parses raw and returns a redacted, length-capped form safe to use
+// as a span attribute or event value. Userinfo, query, and fragment are
+// dropped because they may carry credentials or other sensitive data. It
+// returns an empty string when raw is empty or cannot be parsed.
+func RedactURL(raw string) string {
+	if raw == "" {
+		return ""
+	}
+
+	parsed, err := url.Parse(raw)
+	if err != nil {
+		return ""
+	}
+
+	parsed.User = nil
+	parsed.RawQuery = ""
+	parsed.ForceQuery = false
+	parsed.Fragment = ""
+	parsed.RawFragment = ""
+
+	return CapAttr(parsed.String())
+}
+
+// MapEnum returns value when it belongs to allowed, otherwise "other". It keeps
+// a span attribute or metric dimension bounded even when an upstream tool
+// introduces a new enum value.
+func MapEnum(value string, allowed ...string) string {
+	for _, candidate := range allowed {
+		if value == candidate {
+			return value
+		}
+	}
+	return "other"
+}

pkg/gotenberg/attrs_test.go

@@ -0,0 +1,62 @@
+package gotenberg
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestRedactURL(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		raw  string
+		want string
+	}{
+		{"empty", "", ""},
+		{"strips userinfo query fragment", "https://user:pass@example.com/path?token=secret#frag", "https://example.com/path"},
+		{"keeps host and path", "http://example.com/a/b", "http://example.com/a/b"},
+		{"parse error", "http://example.com/%zz", ""},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := RedactURL(tc.raw); got != tc.want {
+				t.Errorf("RedactURL(%q) = %q, want %q", tc.raw, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestRedactURL_Caps(t *testing.T) {
+	raw := "https://example.com/" + strings.Repeat("a", 400)
+	got := RedactURL(raw)
+	if n := len([]rune(got)); n != maxAttrRunes {
+		t.Errorf("expected capped length %d, got %d", maxAttrRunes, n)
+	}
+}
+
+func TestCapAttr(t *testing.T) {
+	t.Run("short unchanged", func(t *testing.T) {
+		if got := CapAttr("short"); got != "short" {
+			t.Errorf("expected unchanged, got %q", got)
+		}
+	})
+
+	t.Run("multibyte truncated to rune cap", func(t *testing.T) {
+		got := CapAttr(strings.Repeat("é", 400))
+		if n := len([]rune(got)); n != maxAttrRunes {
+			t.Errorf("expected %d runes, got %d", maxAttrRunes, n)
+		}
+		if !strings.HasSuffix(got, "…") {
+			t.Error("expected an ellipsis suffix on a truncated value")
+		}
+	})
+}
+
+func TestMapEnum(t *testing.T) {
+	allowed := []string{"document", "stylesheet", "script"}
+
+	if got := MapEnum("script", allowed...); got != "script" {
+		t.Errorf("expected member passthrough, got %q", got)
+	}
+	if got := MapEnum("websocket", allowed...); got != "other" {
+		t.Errorf("expected non-member to map to other, got %q", got)
+	}
+}