metrics: register prometheus collectors only if enabled (#1457)

* collect metrics only if enabled

* Update caddy/caddy.go

Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>

* Update caddy/caddy.go

Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>

---------

Co-authored-by: Kévin Dunglas <kevin@dunglas.fr>

Author: IndraGunawan

caddy/caddy.go

@@ -83,9 +83,17 @@ func (f FrankenPHPApp) CaddyModule() caddy.ModuleInfo {
 
 // Provision sets up the module.
 func (f *FrankenPHPApp) Provision(ctx caddy.Context) error {
-	f.metrics = frankenphp.NewPrometheusMetrics(ctx.GetMetricsRegistry())
 	f.logger = ctx.Logger()
 
+	if httpApp, err := ctx.AppIfConfigured("http"); err == nil {
+		if httpApp.(*caddyhttp.App).Metrics != nil {
+			f.metrics = frankenphp.NewPrometheusMetrics(ctx.GetMetricsRegistry())
+		}
+	} else {
+		// if the http module is not configured (this should never happen) then collect the metrics by default
+		f.metrics = frankenphp.NewPrometheusMetrics(ctx.GetMetricsRegistry())
+	}
+
 	return nil
 }
 

caddy/caddy_test.go

@@ -325,6 +325,7 @@ func TestMetrics(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp
 	}
@@ -405,6 +406,7 @@ func TestWorkerMetrics(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp {
 			worker ../testdata/index.php 2
@@ -502,6 +504,7 @@ func TestNamedWorkerMetrics(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp {
 			worker {
@@ -594,6 +597,7 @@ func TestAutoWorkerConfig(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp {
 			worker ../testdata/index.php
@@ -873,6 +877,7 @@ func TestMultiWorkersMetrics(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp {
 			worker {
@@ -979,6 +984,7 @@ func TestMultiWorkersMetricsWithDuplicateName(t *testing.T) {
 		admin localhost:2999
 		http_port `+testPort+`
 		https_port 9443
+		metrics
 
 		frankenphp {
 			worker {
@@ -1073,3 +1079,81 @@ func TestMultiWorkersMetricsWithDuplicateName(t *testing.T) {
 			"frankenphp_ready_workers",
 		))
 }
+
+func TestDisabledMetrics(t *testing.T) {
+	var wg sync.WaitGroup
+	tester := caddytest.NewTester(t)
+	tester.InitServer(`
+	{
+		skip_install_trust
+		admin localhost:2999
+		http_port `+testPort+`
+		https_port 9443
+
+		frankenphp {
+			worker {
+				name service1
+				file ../testdata/index.php
+				num 2
+			}
+			worker {
+				name service1
+				file ../testdata/ini.php
+				num 3
+			}
+		}
+	}
+
+	localhost:`+testPort+` {
+		route {
+			php {
+				root ../testdata
+			}
+		}
+	}
+
+	example.com:`+testPort+` {
+		route {
+			php {
+				root ../testdata
+			}
+		}
+	}
+	`, "caddyfile")
+
+	// Make some requests
+	for i := 0; i < 10; i++ {
+		wg.Add(1)
+		go func(i int) {
+			tester.AssertGetResponse(fmt.Sprintf("http://localhost:"+testPort+"/index.php?i=%d", i), http.StatusOK, fmt.Sprintf("I am by birth a Genevese (%d)", i))
+			wg.Done()
+		}(i)
+	}
+	wg.Wait()
+
+	// Fetch metrics
+	resp, err := http.Get("http://localhost:2999/metrics")
+	require.NoError(t, err, "failed to fetch metrics")
+	defer resp.Body.Close()
+
+	// Read and parse metrics
+	metrics := new(bytes.Buffer)
+	_, err = metrics.ReadFrom(resp.Body)
+	require.NoError(t, err, "failed to read metrics")
+
+	ctx := caddy.ActiveContext()
+	count, err := testutil.GatherAndCount(
+		ctx.GetMetricsRegistry(),
+		"frankenphp_busy_threads",
+		"frankenphp_busy_workers",
+		"frankenphp_queue_depth",
+		"frankenphp_ready_workers",
+		"frankenphp_total_threads",
+		"frankenphp_total_workers",
+		"frankenphp_worker_request_count",
+		"frankenphp_worker_request_time",
+	)
+
+	require.NoError(t, err, "failed to count metrics")
+	require.Zero(t, count, "metrics should be missing")
+}

testdata/performance/k6.Caddyfile

@@ -14,7 +14,6 @@
 		root /go/src/app/testdata
 		php {
 			root /go/src/app/testdata
-			enable_root_symlink false
 		}
 	}
 }

testdata/performance/perf-test.sh

@@ -27,7 +27,7 @@ select filename in ./testdata/performance/*.js; do
 
 	sleep 10
 
-	docker run --entrypoint "" -it -v .:/app -w /app \
+	docker run --entrypoint "" -it --rm -v .:/app -w /app \
 		--add-host "host.docker.internal:host-gateway" \
 		grafana/k6:latest \
 		k6 run -e "CADDY_HOSTNAME=$CADDY_HOSTNAME:8125" "./$filename"