troubleshoot basic envoy stats for an upstream (#16215)

* troubleshoot basic envoy stats for an upstream

* remove envoyID arg

troubleshoot/proxy/stats.go

@@ -3,8 +3,8 @@ package troubleshoot
 import (
 	"encoding/json"
 	"fmt"
-
 	envoy_admin_v3 "github.com/envoyproxy/go-control-plane/envoy/admin/v3"
+	"github.com/hashicorp/consul/troubleshoot/validate"
 )
 
 type statsJson struct {
@@ -16,6 +16,45 @@ type simpleMetric struct {
 	Name  string `json:"name,omitempty"`
 }
 
+func (t *Troubleshoot) troubleshootStats() (validate.Messages, error) {
+
+	statMessages := validate.Messages{}
+
+	rejectionStats, err := t.getEnvoyStats("update_rejected")
+	if err != nil {
+		return nil, fmt.Errorf("could not get config rejection stats from envoy admin API: %w", err)
+	}
+
+	totalConfigRejections := 0
+	for _, rs := range rejectionStats {
+		if rs.Value != 0 {
+			totalConfigRejections += int(rs.Value)
+		}
+	}
+
+	statMessages = append(statMessages, validate.Message{
+		Success: true,
+		Message: fmt.Sprintf("Envoy has %v rejected configurations", totalConfigRejections),
+	})
+
+	connectionFailureStats, err := t.getEnvoyStats("upstream_cx_connect_fail")
+	if err != nil {
+		return nil, fmt.Errorf("could not get connection failure stats from envoy admin API: %w", err)
+	}
+
+	totalCxFailures := 0
+	for _, cfs := range connectionFailureStats {
+		if cfs.Value != 0 {
+			totalCxFailures += int(cfs.Value)
+		}
+	}
+	statMessages = append(statMessages, validate.Message{
+		Success: true,
+		Message: fmt.Sprintf("Envoy has detected %v connection failure(s).", totalCxFailures),
+	})
+	return statMessages, nil
+}
+
 func (t *Troubleshoot) getEnvoyStats(filter string) ([]*envoy_admin_v3.SimpleMetric, error) {
 
 	var resultErr error

troubleshoot/proxy/troubleshoot_proxy.go

@@ -85,10 +85,11 @@ func (t *Troubleshoot) RunAllTests(upstreamEnvoyID, upstreamIP string) (validate
 	}
 
 	// getStats usage example
-	// rejectionStats, err := t.getEnvoyStats("update_rejected")
-	// if err != nil {
-	// 	resultErr = multierror.Append(resultErr, err)
-	// }
+	messages, err = t.troubleshootStats()
+	if err != nil {
+		return nil, fmt.Errorf("unable to get stats: %w", err)
+	}
+	allTestMessages = append(allTestMessages, messages...)
 
 	// Validate listeners, routes, clusters, endpoints.
 	messages = Validate(indexedResources, upstreamEnvoyID, upstreamIP, true, t.envoyClusters)