Add LocalStackContainer#getEndpoint() (#7037)

Most recent `localstack/localstack` image versions expose only one
port `4566` and services start lazily, no more `SERVICES` env var
is required. For that reason, `getEndpoint()` becomes handy.

Author: eddumelendez

modules/localstack/src/main/java/org/testcontainers/containers/localstack/LocalStackContainer.java

@@ -254,6 +254,35 @@ public URI getEndpointOverride(EnabledService service) {
         }
     }
 
+    /**
+     * Provides an endpoint to communicate with LocalStack service.
+     * The provided endpoint should be set in the AWS Java SDK v2 when building a client, e.g.:
+     * <pre><code>S3Client s3 = S3Client
+             .builder()
+             .endpointOverride(localstack.getEndpoint())
+             .credentialsProvider(StaticCredentialsProvider.create(AwsBasicCredentials.create(
+             localstack.getAccessKey(), localstack.getSecretKey()
+             )))
+             .region(Region.of(localstack.getRegion()))
+             .build()
+             </code></pre>
+     * <p><strong>Please note that this method is only intended to be used for configuring AWS SDK clients
+     * that are running on the test host. If other containers need to call this one, they should be configured
+     * specifically to do so using a Docker network and appropriate addressing.</strong></p>
+     *
+     * @return an {@link URI} endpoint
+     */
+    public URI getEndpoint() {
+        try {
+            final String address = getHost();
+            // resolve IP address and use that as the endpoint so that path-style access is automatically used for S3
+            String ipAddress = InetAddress.getByName(address).getHostAddress();
+            return new URI("http://" + ipAddress + ":" + getMappedPort(PORT));
+        } catch (UnknownHostException | URISyntaxException e) {
+            throw new IllegalStateException("Cannot obtain endpoint URL", e);
+        }
+    }
+
     private int getServicePort(EnabledService service) {
         return legacyMode ? service.getPort() : PORT;
     }

modules/localstack/src/test/java/org/testcontainers/containers/localstack/LocalstackContainerTest.java

@@ -76,7 +76,7 @@ public void s3TestOverBridgeNetwork() throws IOException {
                 .standard()
                 .withEndpointConfiguration(
                     new AwsClientBuilder.EndpointConfiguration(
-                        localstack.getEndpointOverride(Service.S3).toString(),
+                        localstack.getEndpoint().toString(),
                         localstack.getRegion()
                     )
                 )
@@ -115,7 +115,7 @@ public void s3TestUsingAwsSdkV2() {
             // with_aws_sdk_v2 {
             S3Client s3 = S3Client
                 .builder()
-                .endpointOverride(localstack.getEndpointOverride(Service.S3))
+                .endpointOverride(localstack.getEndpoint())
                 .credentialsProvider(
                     StaticCredentialsProvider.create(
                         AwsBasicCredentials.create(localstack.getAccessKey(), localstack.getSecretKey())
@@ -138,7 +138,7 @@ public void sqsTestOverBridgeNetwork() {
                 .standard()
                 .withEndpointConfiguration(
                     new AwsClientBuilder.EndpointConfiguration(
-                        localstack.getEndpointOverride(Service.SQS).toString(),
+                        localstack.getEndpoint().toString(),
                         localstack.getRegion()
                     )
                 )
@@ -171,7 +171,7 @@ public void cloudWatchLogsTestOverBridgeNetwork() {
                 .standard()
                 .withEndpointConfiguration(
                     new AwsClientBuilder.EndpointConfiguration(
-                        localstack.getEndpointOverride(Service.CLOUDWATCHLOGS).toString(),
+                        localstack.getEndpoint().toString(),
                         localstack.getRegion()
                     )
                 )
@@ -195,7 +195,7 @@ public void kmsKeyCreationTest() {
                 .standard()
                 .withEndpointConfiguration(
                     new AwsClientBuilder.EndpointConfiguration(
-                        localstack.getEndpointOverride(Service.KMS).toString(),
+                        localstack.getEndpoint().toString(),
                         localstack.getRegion()
                     )
                 )
@@ -345,7 +345,7 @@ public static class WithRegion {
         @Test
         public void s3EndpointHasProperRegion() {
             final AwsClientBuilder.EndpointConfiguration endpointConfiguration = new AwsClientBuilder.EndpointConfiguration(
-                localstack.getEndpointOverride(Service.S3).toString(),
+                localstack.getEndpoint().toString(),
                 localstack.getRegion()
             );
             assertThat(endpointConfiguration.getSigningRegion())
@@ -366,7 +366,7 @@ public void s3ServiceStartLazily() {
             try (
                 S3Client s3 = S3Client
                     .builder()
-                    .endpointOverride(localstack.getEndpointOverride(Service.S3))
+                    .endpointOverride(localstack.getEndpoint())
                     .credentialsProvider(
                         StaticCredentialsProvider.create(
                             AwsBasicCredentials.create(localstack.getAccessKey(), localstack.getSecretKey())