fix(controller): race condition in handleSigterm() test

Fix a race condition between the signal handler setup and the signal
send in the test for handleSigterm()

Author: vflaux

controller/execute.go

@@ -100,7 +100,7 @@ func Execute() {
 	ctx, cancel := context.WithCancel(context.Background())
 
 	go serveMetrics(cfg.MetricsAddress)
-	go handleSigterm(cancel)
+	setupSigtermHandler(cancel)
 
 	endpointsSource, err := buildSource(ctx, cfg)
 	if err != nil {
@@ -474,14 +474,16 @@ func createDomainFilter(cfg *externaldns.Config) *endpoint.DomainFilter {
 	}
 }
 
-// handleSigterm listens for a SIGTERM signal and triggers the provided cancel function
+// setupSigtermHandler start a routine that listens for a SIGTERM signal and triggers the provided cancel function
 // to gracefully terminate the application. It logs a message when the signal is received.
-func handleSigterm(cancel func()) {
+func setupSigtermHandler(cancel func()) {
 	signals := make(chan os.Signal, 1)
 	signal.Notify(signals, syscall.SIGTERM)
-	<-signals
-	log.Info("Received SIGTERM. Terminating...")
-	cancel()
+	go func() {
+		<-signals
+		log.Info("Received SIGTERM. Terminating...")
+		cancel()
+	}()
 }
 
 // serveMetrics starts an HTTP server that serves health and metrics endpoints.

controller/execute_test.go

@@ -24,8 +24,10 @@ import (
 	"net/http/httptest"
 	"os"
 	"os/exec"
+	"os/signal"
 	"reflect"
 	"regexp"
+	"syscall"
 	"testing"
 	"time"
 
@@ -34,6 +36,7 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"sigs.k8s.io/external-dns/endpoint"
+	"sigs.k8s.io/external-dns/internal/testutils"
 	"sigs.k8s.io/external-dns/pkg/apis/externaldns"
 	"sigs.k8s.io/external-dns/provider"
 	fakeprovider "sigs.k8s.io/external-dns/provider/fakes"
@@ -219,6 +222,40 @@ func TestSelectRegistry(t *testing.T) {
 	}
 }
 
+func TestSetupSigtermHandler(t *testing.T) {
+	cancelCalled := make(chan bool, 1)
+	cancel := func() {
+		cancelCalled <- true
+	}
+
+	hook := testutils.LogsUnderTestWithLogLevel(log.InfoLevel, t)
+
+	defer signal.Reset(syscall.SIGTERM)
+	setupSigtermHandler(cancel)
+
+	// Simulate sending a SIGTERM signal
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGTERM)
+	err := syscall.Kill(syscall.Getpid(), syscall.SIGTERM)
+	assert.NoError(t, err)
+
+	// Wait for the signal to be received
+	select {
+	case sig := <-sigChan:
+		assert.Equal(t, syscall.SIGTERM, sig)
+	case <-time.After(1 * time.Second):
+		t.Fatal("signal was not recieved")
+	}
+
+	// Wait for the cancel function to be called
+	select {
+	case <-cancelCalled:
+		testutils.TestHelperLogContainsWithLogLevel("Received SIGTERM. Terminating...", log.InfoLevel, hook, t)
+	case <-time.After(1 * time.Second):
+		t.Fatal("cancel function was not called")
+	}
+}
+
 // Provider
 func TestBuildProvider(t *testing.T) {
 	tests := []struct {