From 7f9c4f8670287314dc889183203ae49f82320383 Mon Sep 17 00:00:00 2001
From: patoarvizu <patoarvizu@gmail.com>
Date: Tue, 31 Mar 2020 20:20:39 -0400
Subject: [PATCH] Add metrics endpoint

---
 cmd/webhook/main.go                           | 27 +++++++++++++++----
 deploy/operator.yaml                          |  2 ++
 go.mod                                        |  1 +
 .../templates/deployment.yaml                 |  2 ++
 4 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/cmd/webhook/main.go b/cmd/webhook/main.go
index ea4c0cd..647df6e 100644
--- a/cmd/webhook/main.go
+++ b/cmd/webhook/main.go
@@ -15,6 +15,10 @@ import (
 	"github.com/slok/kubewebhook/pkg/log"
 	validatingwh "github.com/slok/kubewebhook/pkg/webhook/validating"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/slok/kubewebhook/pkg/observability/metrics"
 )
 
 type webhookCfg struct {
@@ -115,15 +119,28 @@ func main() {
 		Name: "kms-vault-secret-validator",
 		Obj:  &kmsvaultv1alpha1.KMSVaultSecret{},
 	}
-
-	wh, err := validatingwh.NewWebhook(vhc, v, nil, nil, logger)
+	reg := prometheus.NewRegistry()
+	metricsRec := metrics.NewPrometheus(reg)
+	wh, err := validatingwh.NewWebhook(vhc, v, nil, metricsRec, logger)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "error creating webhook: %s", err)
 		os.Exit(1)
 	}
-	err = http.ListenAndServeTLS(cfg.addr, cfg.certFile, cfg.keyFile, whhttp.MustHandlerFor(wh))
-	if err != nil {
-		fmt.Fprintf(os.Stderr, "error serving webhook: %s", err)
+	webhookError := make(chan error)
+	go func() {
+		webhookError <- http.ListenAndServeTLS(cfg.addr, cfg.certFile, cfg.keyFile, whhttp.MustHandlerFor(wh))
+	}()
+	metricsError := make(chan error)
+	promHandler := promhttp.HandlerFor(reg, promhttp.HandlerOpts{})
+	go func() {
+		metricsError <- http.ListenAndServe(cfg.metricsAddr, promHandler)
+	}()
+	if <-webhookError != nil {
+		fmt.Fprintf(os.Stderr, "error serving webhook: %s", <-webhookError)
+		os.Exit(1)
+	}
+	if <-metricsError != nil {
+		fmt.Fprintf(os.Stderr, "error serving metrics: %s", <-metricsError)
 		os.Exit(1)
 	}
 }
diff --git a/deploy/operator.yaml b/deploy/operator.yaml
index 0a42712..a3b9d2b 100644
--- a/deploy/operator.yaml
+++ b/deploy/operator.yaml
@@ -57,6 +57,8 @@ spec:
           ports:
           - name: https
             containerPort: 4443
+          - name: metrics
+            containerPort: 8081
           volumeMounts:
             - name: tls
               mountPath: /tls
diff --git a/go.mod b/go.mod
index 312bfe5..3dd8dba 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/go-openapi/spec v0.19.4
 	github.com/hashicorp/vault/api v1.0.4
 	github.com/operator-framework/operator-sdk v0.15.1
+	github.com/prometheus/client_golang v1.2.1
 	github.com/slok/kubewebhook v0.9.0
 	github.com/spf13/pflag v1.0.5
 	k8s.io/api v0.18.0
diff --git a/helm/kms-vault-operator/templates/deployment.yaml b/helm/kms-vault-operator/templates/deployment.yaml
index 67b3a5f..0b6ff61 100644
--- a/helm/kms-vault-operator/templates/deployment.yaml
+++ b/helm/kms-vault-operator/templates/deployment.yaml
@@ -89,6 +89,8 @@ spec:
           ports:
           - name: https
             containerPort: 4443
+          - name: metrics
+            containerPort: 8081
           volumeMounts:
             - name: tls
               mountPath: /tls