Remove non-specific webhook request metrics (open-policy-agent#1428)

As g8r once had only a validation webhook, certain metrics
(request_count, request_count_duration_seconds) were implemented without
qualifiers.  i.e., the fact that they applied to the validation webhook
was _assumed_.

As g8r now has both validation and mutation webhooks, separate metrics
for both are required.  These metrics have already been implemented, and
have been released since v3.4.0.  The original metrics were deprecated
(but retained) at the time of that release.

As we are approaching v3.6, it is finally time to remove these metrics.
This PR removes the code and updates the metrics README.

Fixes open-policy-agent#1010

Signed-off-by: juliankatz <juliankatz@google.com>

pkg/webhook/stats_reporter.go

@@ -11,9 +11,6 @@ import (
 )
 
 const (
-	requestCountMetricName    = "request_count"
-	requestDurationMetricName = "request_duration_seconds"
-
 	validationRequestCountMetricName    = "validation_request_count"
 	validationRequestDurationMetricName = "validation_request_duration_seconds"
 
@@ -22,11 +19,6 @@ const (
 )
 
 var (
-	responseTimeInSecM = stats.Float64(
-		requestDurationMetricName,
-		"The response time in seconds",
-		stats.UnitSeconds)
-
 	validationResponseTimeInSecM = stats.Float64(
 		validationRequestDurationMetricName,
 		"The response time in seconds",
@@ -71,9 +63,6 @@ func newStatsReporter() (StatsReporter, error) {
 }
 
 func (r *reporter) ReportValidationRequest(response requestResponse, d time.Duration) error {
-	if err := r.reportRequest(response, admissionStatusKey, responseTimeInSecM.M(d.Seconds())); err != nil {
-		return err
-	}
 	return r.reportRequest(response, admissionStatusKey, validationResponseTimeInSecM.M(d.Seconds()))
 }
 
@@ -100,20 +89,6 @@ func (r *reporter) report(ctx context.Context, m stats.Measurement) error {
 
 func register() error {
 	views := []*view.View{
-		{
-			Name:        requestCountMetricName,
-			Description: "The number of requests that are routed to validation webhook",
-			Measure:     responseTimeInSecM,
-			Aggregation: view.Count(),
-			TagKeys:     []tag.Key{admissionStatusKey},
-		},
-		{
-			Name:        requestDurationMetricName,
-			Description: responseTimeInSecM.Description(),
-			Measure:     responseTimeInSecM,
-			Aggregation: view.Distribution(0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05),
-			TagKeys:     []tag.Key{admissionStatusKey},
-		},
 		{
 			Name:        validationRequestCountMetricName,
 			Description: "The number of requests that are routed to validation webhook",

pkg/webhook/stats_reporter_test.go

@@ -31,7 +31,6 @@ func TestValidationReportRequest(t *testing.T) {
 	if err != nil {
 		t.Errorf("ReportRequest error %v", err)
 	}
-	check(t, expectedTags, requestCountMetricName, requestDurationMetricName)
 	check(t, expectedTags, validationRequestCountMetricName, validationRequestDurationMetricName)
 }
 

website/docs/metrics.md

@@ -53,19 +53,39 @@ Below are the list of metrics provided by Gatekeeper:
 
 ## Webhook
 
-- Name: `request_count`
+- Name: `validation_request_count`
 
-    Description: `The number of requests that are routed to webhook`
+    Description: `The number of requests that are routed to validation webhook`
 
     Tags:
 
     - `admission_status`: [`allow`, `deny`]
 
     Aggregation: `Count`
 
-- Name: `request_duration_seconds`
+- Name: `validation_request_duration_seconds`
 
-    Description: `The response time in seconds`
+    Description: `The validation webhook response time in seconds`
+
+    Tags:
+
+    - `admission_status`: [`allow`, `deny`]
+
+    Aggregation: `Distribution`
+
+- Name: `mutation_request_count`
+
+    Description: `The number of requests that are routed to mutation webhook`
+
+    Tags:
+
+    - `admission_status`: [`allow`, `deny`]
+
+    Aggregation: `Count`
+
+- Name: `mutation_request_duration_seconds`
+
+    Description: `The mutation webhook response time in seconds`
 
     Tags: