filters/auth: add tracing tag for jwtMetrics

Add tracing tag for requests with problematic JWT tokens.

Signed-off-by: Alexander Yastrebov <alexander.yastrebov@zalando.de>

filters/auth/jwt_metrics.go

@@ -7,6 +7,7 @@ import (
 	"strings"
 
 	"github.com/ghodss/yaml"
+	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
 	"github.com/zalando/skipper/filters/annotate"
 	"github.com/zalando/skipper/jwt"
@@ -75,33 +76,40 @@ func (f *jwtMetricsFilter) Response(ctx filters.FilterContext) {
 
 	request := ctx.Request()
 
-	metrics := ctx.Metrics()
-	metricsPrefix := fmt.Sprintf("%s.%s.%d.", request.Method, escapeMetricKeySegment(request.Host), response.StatusCode)
+	count := func(metric string) {
+		prefix := fmt.Sprintf("%s.%s.%d.", request.Method, escapeMetricKeySegment(request.Host), response.StatusCode)
+
+		ctx.Metrics().IncCounter(prefix + metric)
+
+		if span := opentracing.SpanFromContext(ctx.Request().Context()); span != nil {
+			span.SetTag("jwt", metric)
+		}
+	}
 
 	ahead := request.Header.Get("Authorization")
 	if ahead == "" {
-		metrics.IncCounter(metricsPrefix + "missing-token")
+		count("missing-token")
 		return
 	}
 
 	tv := strings.TrimPrefix(ahead, "Bearer ")
 	if tv == ahead {
-		metrics.IncCounter(metricsPrefix + "invalid-token-type")
+		count("invalid-token-type")
 		return
 	}
 
 	if len(f.Issuers) > 0 {
 		token, err := jwt.Parse(tv)
 		if err != nil {
-			metrics.IncCounter(metricsPrefix + "invalid-token")
+			count("invalid-token")
 			return
 		}
 
 		// https://datatracker.ietf.org/doc/html/rfc7519#section-4.1.1
 		if issuer, ok := token.Claims["iss"].(string); !ok {
-			metrics.IncCounter(metricsPrefix + "missing-issuer")
+			count("missing-issuer")
 		} else if !slices.Contains(f.Issuers, issuer) {
-			metrics.IncCounter(metricsPrefix + "invalid-issuer")
+			count("invalid-issuer")
 		}
 	}
 }

filters/auth/jwt_metrics_test.go

@@ -9,6 +9,7 @@ import (
 	"net/url"
 	"testing"
 
+	"github.com/opentracing/opentracing-go/mocktracer"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/zalando/skipper/eskip"
@@ -31,11 +32,12 @@ func TestJwtMetrics(t *testing.T) {
 	defer testAuthServer.Close()
 
 	for _, tc := range []struct {
-		name     string
-		filters  string
-		request  *http.Request
-		status   int
-		expected map[string]int64
+		name        string
+		filters     string
+		request     *http.Request
+		status      int
+		expected    map[string]int64
+		expectedTag string
 	}{
 		{
 			name:     "ignores 401 response",
@@ -66,6 +68,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.missing-token": 1,
 			},
+			expectedTag: "missing-token",
 		},
 		{
 			name:    "invalid-token-type",
@@ -77,6 +80,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.invalid-token-type": 1,
 			},
+			expectedTag: "invalid-token-type",
 		},
 		{
 			name:    "invalid-token",
@@ -88,6 +92,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.invalid-token": 1,
 			},
+			expectedTag: "invalid-token",
 		},
 		{
 			name:    "missing-issuer",
@@ -101,6 +106,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.missing-issuer": 1,
 			},
+			expectedTag: "missing-issuer",
 		},
 		{
 			name:    "invalid-issuer",
@@ -114,6 +120,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.invalid-issuer": 1,
 			},
+			expectedTag: "invalid-issuer",
 		},
 		{
 			name:    "no invalid-issuer for empty issuers",
@@ -156,6 +163,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.missing-token": 1,
 			},
+			expectedTag: "missing-token",
 		},
 		{
 			name: "no metrics when opted-out by annotation",
@@ -188,6 +196,7 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.missing-token": 1,
 			},
+			expectedTag: "missing-token",
 		},
 		{
 			name: "no metrics when opted-out by state bag",
@@ -220,11 +229,13 @@ func TestJwtMetrics(t *testing.T) {
 			expected: map[string]int64{
 				"jwtMetrics.custom.GET.foo_test.200.invalid-token": 1,
 			},
+			expectedTag: "invalid-token",
 		},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			m := &metricstest.MockMetrics{}
 			defer m.Close()
+			tracer := mocktracer.New()
 
 			fr := builtin.MakeRegistry()
 			fr.Register(auth.NewJwtMetrics())
@@ -236,6 +247,10 @@ func TestJwtMetrics(t *testing.T) {
 				Routes: eskip.MustParse(fmt.Sprintf(`* -> %s -> status(%d) -> <shunt>`, tc.filters, tc.status)),
 				ProxyParams: proxy.Params{
 					Metrics: m,
+					OpenTracing: &proxy.OpenTracingParams{
+						Tracer:             tracer,
+						DisableFilterSpans: true,
+					},
 				},
 			}.Create()
 			defer p.Close()
@@ -249,6 +264,16 @@ func TestJwtMetrics(t *testing.T) {
 			resp.Body.Close()
 			require.Equal(t, tc.status, resp.StatusCode)
 
+			spans := tracer.FinishedSpans()
+			require.Len(t, spans, 1)
+			span := spans[0]
+
+			if tc.expectedTag == "" {
+				assert.Nil(t, span.Tag("jwt"))
+			} else {
+				assert.Equal(t, tc.expectedTag, span.Tag("jwt"))
+			}
+
 			m.WithCounters(func(counters map[string]int64) {
 				// add incoming counter to simplify comparison
 				tc.expected["incoming.HTTP/1.1"] = 1