Add opt-in option for Prometheus (#162)

* Enable to opt-in prometheus

* Add docs

Author: Noah Hanjun Lee

cmd/server/config.go

@@ -60,6 +60,7 @@ type (
 	}
 
 	Prometheus struct {
+		PrometheusEnabled    bool   `split_words:"true"`
 		PrometheusAuthSecret string `split_words:"true"`
 	}
 )

cmd/server/main.go

@@ -96,6 +96,7 @@ func newServerConfig(c *Config) *server.ServerConfig {
 		ProxyHost:            proxyHost,
 		ProxyProto:           proxyProto,
 		WebhookSecret:        c.WebhookSecret,
+		PrometheusEnabled:    c.PrometheusEnabled,
 		PrometheusAuthSecret: c.PrometheusAuthSecret,
 	}
 }

docs/concepts/metrics.md

@@ -1,12 +1,13 @@
 # Metrics
 
-Gtiploy publishes and exposes metrics that Prometheus can consume at the standard `/metrics` endpoint.
+Gtiploy publishes and exposes metrics that Prometheus can consume at the standard `/metrics` endpoint. 
 
 ## Configuration
 
 1\. Configure the server:
 
 ```
+GITPLOY_PROMETHEUS_ENABLED=true
 GITPLOY_PROMETHEUS_AUTH_SECRET=YOUR_SECRET
 ```
 

docs/references/GITPLOY_PROMETHEUS_ENABLED.md

@@ -0,0 +1,7 @@
+# GITPLOY_PROMETHEUS_ENABLED
+
+Optional string value to enable exposing metrics that Prometheus can consume. The default value is `false`.
+
+```
+GITPLOY_PROMETHEUS_ENABLED=true
+```

docs/references/configurations.md

@@ -10,6 +10,7 @@ Index of server configuration settings:
 * [GITPLOY_LICENSE](./GITPLOY_LICENSE.md)
 * [GITPLOY_MEMBER_ENTRIES](./GITPLOY_MEMBER_ENTRIES.md)
 * [GITPLOY_PROMETHEUS_AUTH_SECRET](./GITPLOY_PROMETHEUS_AUTH_SECRET.md)
+* [GITPLOY_PROMETHEUS_ENABLED](./GITPLOY_PROMETHEUS_ENABLED.md)
 * [GITPLOY_ORGANIZATION_ENTRIES](./GITPLOY_ORGANIZATION_ENTRIES.md)
 * [GITPLOY_PROXY_SERVER_HOST](./GITPLOY_PROXY_SERVER_HOST.md)
 * [GITPLOY_PROXY_SERVER_PROTO](./GITPLOY_PROXY_SERVER_PROTO.md)

internal/server/router.go

@@ -42,7 +42,9 @@ type (
 		ProxyHost  string
 		ProxyProto string
 
-		WebhookSecret        string
+		WebhookSecret string
+
+		PrometheusEnabled    bool
 		PrometheusAuthSecret string
 	}
 
@@ -101,7 +103,6 @@ func NewRouter(c *RouterConfig) *gin.Engine {
 	gm := gb.NewMiddleware(c.Interactor)
 	r.Use(
 		gm.SetUser(),
-		metrics.CollectRequestMetrics(),
 	)
 
 	v1 := r.Group("/api/v1")
@@ -201,11 +202,13 @@ func NewRouter(c *RouterConfig) *gin.Engine {
 
 	metricsapi := r.Group("/metrics")
 	{
+		r.Use(metrics.CollectRequestMetrics())
+
 		m := metrics.NewMetric(&metrics.MetricConfig{
 			Interactor:           c.Interactor,
 			PrometheusAuthSecret: c.PrometheusAuthSecret,
 		})
-		metricsapi.GET("", m.CollectMetrics)
+		metricsapi.GET("", hasOptIn(c.PrometheusEnabled), m.CollectMetrics)
 	}
 
 	r.HEAD("/slack", func(gc *gin.Context) {
@@ -303,3 +306,12 @@ func newSlackOauthConfig(c *RouterConfig) *oauth2.Config {
 func isSlackEnabled(c *RouterConfig) bool {
 	return c.ChatConfig != nil && c.ChatConfig.Type == ChatTypeSlack
 }
+
+func hasOptIn(enabled bool) gin.HandlerFunc {
+	return func(c *gin.Context) {
+		if !enabled {
+			c.AbortWithStatus(http.StatusNotFound)
+			return
+		}
+	}
+}