fix(modules.kafka): Use broker container IP instead of host IP for ad…

…vertised broker listener (testcontainers#1989)

* Fix advertised broker ip

port 9092 is not exposed to the host, so we can not connect to it via host ip, but need to use the broker container ip

* Add fn to fetch the hostname

* chore: use the new Inspect method instead

* chore: add test

---------

Co-authored-by: Manuel de la Peña <mdelapenya@gmail.com>
Co-authored-by: Eddú Meléndez <eddu.melendez@gmail.com>

modules/kafka/kafka.go

@@ -72,12 +72,19 @@ func RunContainer(ctx context.Context, opts ...testcontainers.ContainerCustomize
 							return err
 						}
 
+						inspect, err := c.Inspect(ctx)
+						if err != nil {
+							return err
+						}
+
+						hostname := inspect.Config.Hostname
+
 						port, err := c.MappedPort(ctx, publicPort)
 						if err != nil {
 							return err
 						}
 
-						scriptContent := fmt.Sprintf(starterScriptContent, host, port.Int(), host)
+						scriptContent := fmt.Sprintf(starterScriptContent, host, port.Int(), hostname)
 
 						return c.CopyToContainer(ctx, []byte(scriptContent), starterScript, 0o755)
 					},

modules/kafka/kafka_test.go

@@ -2,6 +2,7 @@ package kafka_test
 
 import (
 	"context"
+	"io"
 	"strings"
 	"testing"
 
@@ -28,6 +29,8 @@ func TestKafka(t *testing.T) {
 		}
 	})
 
+	assertAdvertisedListeners(t, kafkaContainer)
+
 	if !strings.EqualFold(kafkaContainer.ClusterID, "kraftCluster") {
 		t.Fatalf("expected clusterID to be %s, got %s", "kraftCluster", kafkaContainer.ClusterID)
 	}
@@ -93,3 +96,32 @@ func TestKafka_invalidVersion(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+// assertAdvertisedListeners checks that the advertised listeners are set correctly:
+// - The BROKER:// protocol is using the hostname of the Kafka container
+func assertAdvertisedListeners(t *testing.T, container testcontainers.Container) {
+	inspect, err := container.Inspect(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	hostname := inspect.Config.Hostname
+
+	code, r, err := container.Exec(context.Background(), []string{"cat", "/usr/sbin/testcontainers_start.sh"})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if code != 0 {
+		t.Fatalf("expected exit code to be 0, got %d", code)
+	}
+
+	bs, err := io.ReadAll(r)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !strings.Contains(string(bs), "BROKER://"+hostname+":9092") {
+		t.Fatalf("expected advertised listeners to contain %s, got %s", "BROKER://"+hostname+":9092", string(bs))
+	}
+}