test(cmd/main/TestRuntimeGOGCConfig): add checks on reloads as well

Signed-off-by: machine424 <ayoubmrini424@gmail.com>

cmd/prometheus/main_test.go

@@ -650,6 +650,16 @@ func TestRwProtoMsgFlagParser(t *testing.T) {
 	}
 }
 
+// reloadPrometheusConfig sends a reload request to the Prometheus server to apply
+// updated configurations.
+func reloadPrometheusConfig(t *testing.T, reloadURL string) {
+	t.Helper()
+
+	r, err := http.Post(reloadURL, "text/plain", nil)
+	require.NoError(t, err, "Failed to reload Prometheus")
+	require.Equal(t, http.StatusOK, r.StatusCode, "Unexpected status code when reloading Prometheus")
+}
+
 func getGaugeValue(t *testing.T, body io.ReadCloser, metricName string) (float64, error) {
 	t.Helper()
 
@@ -679,7 +689,7 @@ func TestRuntimeGOGCConfig(t *testing.T) {
 		name         string
 		config       string
 		gogcEnvVar   string
-		expectedGOGC int
+		expectedGOGC float64
 	}{
 		{
 			name:         "empty config file",
@@ -695,7 +705,7 @@ func TestRuntimeGOGCConfig(t *testing.T) {
 			config: `
 runtime:
   gogc: 77`,
-			expectedGOGC: 77,
+			expectedGOGC: 77.0,
 		},
 		{
 			name: "gogc set through config and env var",
@@ -703,20 +713,20 @@ runtime:
 runtime:
   gogc: 77`,
 			gogcEnvVar:   "88",
-			expectedGOGC: 77,
+			expectedGOGC: 77.0,
 		},
 		{
 			name: "incomplete runtime block",
 			config: `
 runtime:`,
-			expectedGOGC: 75,
+			expectedGOGC: 75.0,
 		},
 		{
 			name: "incomplete runtime block and GOGC env var set",
 			config: `
 runtime:`,
 			gogcEnvVar:   "88",
-			expectedGOGC: 88,
+			expectedGOGC: 88.0,
 		},
 		{
 			name: "unrelated config and GOGC env var set",
@@ -735,7 +745,13 @@ global:
 
 			port := testutil.RandomUnprivilegedPort(t)
 			os.WriteFile(configFile, []byte(tc.config), 0o777)
-			prom := prometheusCommandWithLogging(t, configFile, port, fmt.Sprintf("--storage.tsdb.path=%s", tmpDir))
+			prom := prometheusCommandWithLogging(
+				t,
+				configFile,
+				port,
+				fmt.Sprintf("--storage.tsdb.path=%s", tmpDir),
+				"--web.enable-lifecycle",
+			)
 			// Inject GOGC when set.
 			prom.Env = os.Environ()
 			if tc.gogcEnvVar != "" {
@@ -743,24 +759,42 @@ global:
 			}
 			require.NoError(t, prom.Start())
 
-			var (
+			ensureGOGCValue := func(val float64) {
-				r   *http.Response
+				var (
-				err error
+					r   *http.Response
-			)
+					err error
-			// Wait for the /metrics endpoint to be ready.
+				)
-			require.Eventually(t, func() bool {
+				// Wait for the /metrics endpoint to be ready.
-				r, err = http.Get(fmt.Sprintf("http://127.0.0.1:%d/metrics", port))
+				require.Eventually(t, func() bool {
-				if err != nil {
+					r, err = http.Get(fmt.Sprintf("http://127.0.0.1:%d/metrics", port))
-					return false
+					if err != nil {
-				}
+						return false
-				return r.StatusCode == http.StatusOK
+					}
-			}, 5*time.Second, 50*time.Millisecond)
+					return r.StatusCode == http.StatusOK
-			defer r.Body.Close()
+				}, 5*time.Second, 50*time.Millisecond)
+				defer r.Body.Close()
 
-			// Check the final GOGC that's set, consider go_gc_gogc_percent from /metrics as source of truth.
+				// Check the final GOGC that's set, consider go_gc_gogc_percent from /metrics as source of truth.
-			gogc, err := getGaugeValue(t, r.Body, "go_gc_gogc_percent")
+				gogc, err := getGaugeValue(t, r.Body, "go_gc_gogc_percent")
-			require.NoError(t, err)
+				require.NoError(t, err)
-			require.Equal(t, float64(tc.expectedGOGC), gogc)
+				require.Equal(t, val, gogc)
+			}
+
+			// The value is applied on startup.
+			ensureGOGCValue(tc.expectedGOGC)
+
+			// After a reload with the same config, the value stays the same.
+			reloadURL := fmt.Sprintf("http://127.0.0.1:%d/-/reload", port)
+			reloadPrometheusConfig(t, reloadURL)
+			ensureGOGCValue(tc.expectedGOGC)
+
+			// After a reload with different config, the value gets updated.
+			newConfig := `
+runtime:
+  gogc: 99`
+			os.WriteFile(configFile, []byte(newConfig), 0o777)
+			reloadPrometheusConfig(t, reloadURL)
+			ensureGOGCValue(99.0)
 		})
 	}
 }

cmd/prometheus/query_log_test.go

@@ -95,13 +95,6 @@ func (p *queryLogTest) setQueryLog(t *testing.T, queryLogFile string) {
 	require.NoError(t, err)
 }
 
-// reloadConfig reloads the configuration using POST.
-func (p *queryLogTest) reloadConfig(t *testing.T) {
-	r, err := http.Post(fmt.Sprintf("http://%s:%d%s/-/reload", p.host, p.port, p.prefix), "text/plain", nil)
-	require.NoError(t, err)
-	require.Equal(t, 200, r.StatusCode)
-}
-
 // query runs a query according to the test origin.
 func (p *queryLogTest) query(t *testing.T) {
 	switch p.origin {
@@ -308,6 +301,7 @@ func (p *queryLogTest) run(t *testing.T) {
 	}, p.params()...)
 
 	prom := exec.Command(promPath, params...)
+	reloadURL := fmt.Sprintf("http://%s:%d%s/-/reload", p.host, p.port, p.prefix)
 
 	// Log stderr in case of failure.
 	stderr, err := prom.StderrPipe()
@@ -335,7 +329,7 @@ func (p *queryLogTest) run(t *testing.T) {
 		p.query(t)
 		require.Empty(t, readQueryLog(t, queryLogFile.Name()))
 		p.setQueryLog(t, queryLogFile.Name())
-		p.reloadConfig(t)
+		reloadPrometheusConfig(t, reloadURL)
 	}
 
 	p.query(t)
@@ -350,7 +344,7 @@ func (p *queryLogTest) run(t *testing.T) {
 	p.validateLastQuery(t, ql)
 
 	p.setQueryLog(t, "")
-	p.reloadConfig(t)
+	reloadPrometheusConfig(t, reloadURL)
 	if !p.exactQueryCount() {
 		qc = len(readQueryLog(t, queryLogFile.Name()))
 	}
@@ -362,7 +356,7 @@ func (p *queryLogTest) run(t *testing.T) {
 
 	qc = len(ql)
 	p.setQueryLog(t, queryLogFile.Name())
-	p.reloadConfig(t)
+	reloadPrometheusConfig(t, reloadURL)
 
 	p.query(t)
 	qc++
@@ -406,7 +400,7 @@ func (p *queryLogTest) run(t *testing.T) {
 	}
 	p.validateLastQuery(t, ql)
 
-	p.reloadConfig(t)
+	reloadPrometheusConfig(t, reloadURL)
 
 	p.query(t)
 

cmd/prometheus/scrape_failure_log_test.go

@@ -112,7 +112,8 @@ scrape_configs:
 	require.NoError(t, err, "Failed to update Prometheus configuration file")
 
 	// Reload Prometheus with the updated configuration.
-	reloadPrometheus(t, port)
+	reloadURL := fmt.Sprintf("http://127.0.0.1:%d/-/reload", port)
+	reloadPrometheusConfig(t, reloadURL)
 
 	// Count the number of lines in the scrape failure log file before any
 	// further requests.
@@ -146,7 +147,7 @@ scrape_configs:
 	require.NoError(t, err, "Failed to update Prometheus configuration file")
 
 	// Reload Prometheus with the updated configuration.
-	reloadPrometheus(t, port)
+	reloadPrometheusConfig(t, reloadURL)
 
 	// Wait for at least two more requests to the mock server and verify that
 	// new log entries are created.
@@ -160,14 +161,6 @@ scrape_configs:
 	require.Greater(t, countLinesInFile(scrapeFailureLogFile), postReloadLogLineCount, "New lines should be added to the scrape failure log file after re-adding the log setting")
 }
 
-// reloadPrometheus sends a reload request to the Prometheus server to apply
-// updated configurations.
-func reloadPrometheus(t *testing.T, port int) {
-	resp, err := http.Post(fmt.Sprintf("http://127.0.0.1:%d/-/reload", port), "", nil)
-	require.NoError(t, err, "Failed to reload Prometheus")
-	require.Equal(t, http.StatusOK, resp.StatusCode, "Unexpected status code when reloading Prometheus")
-}
-
 // startGarbageServer sets up a mock server that returns a 500 Internal Server Error
 // for all requests. It also increments the request count each time it's hit.
 func startGarbageServer(t *testing.T, requestCount *atomic.Int32) string {