Fix ServiceBindingMapper for IAS configuration without domains (#1153)

* Fix ServiceBindingMapper throwing exception when IAS configuration has no 'domains' key in credentials.
For backward compatibility, it also accepts single String values under key 'domain'.

env/src/main/java/com/sap/cloud/security/config/ServiceBindingMapper.java

@@ -7,9 +7,11 @@
 import org.slf4j.LoggerFactory;
 
 import javax.annotation.Nullable;
+import java.util.Collections;
 import java.util.List;
 
 import static com.sap.cloud.security.config.Service.IAS;
+import static com.sap.cloud.security.config.cf.CFConstants.IAS.DOMAIN;
 import static com.sap.cloud.security.config.cf.CFConstants.IAS.DOMAINS;
 import static com.sap.cloud.security.config.cf.CFConstants.SERVICE_PLAN;
 
@@ -33,17 +35,36 @@ public static OAuth2ServiceConfigurationBuilder mapToOAuth2ServiceConfigurationB
 			return null;
 		}
 
+		TypedMapView credentials = TypedMapView.ofCredentials(b);
 		OAuth2ServiceConfigurationBuilder builder = OAuth2ServiceConfigurationBuilder.forService(service)
-				.withProperties(TypedMapView.ofCredentials(b).getEntries(String.class))
-				.withProperty(SERVICE_PLAN,
-						b.getServicePlan().orElse(K8sConstants.Plan.APPLICATION.name()).toUpperCase());
+				.withProperties(credentials.getEntries(String.class))
+				.withProperty(SERVICE_PLAN, b.getServicePlan().orElse(K8sConstants.Plan.APPLICATION.name()).toUpperCase());
 
 		if (IAS.equals(service)) {
-			List<String> domains = TypedMapView.ofCredentials(b).getListView(DOMAINS).getItems(String.class);
-			LOGGER.info("first domain : {}", domains.get(0));
-			builder.withDomains(domains.toArray(new String[] {}));
+			parseDomains(builder, credentials);
 		}
 
 		return builder;
 	}
+
+	/**
+	 * Parses the 'domains' key in the credentials of an IAS configuration and configures the given builder with them if present.
+	 * For backward compatibility, domains may also be provided via key 'domain'.
+	 *
+	 * @param credentials value of JSON key 'credentials' in an IAS service configuration
+	 */
+	private static void parseDomains(OAuth2ServiceConfigurationBuilder builder, TypedMapView credentials) {
+		List<String> domains;
+		if(credentials.getKeys().contains(DOMAINS)) {
+			domains = credentials.getListView(DOMAINS).getItems(String.class);
+		} else if (credentials.getKeys().contains(DOMAIN)) {
+			domains = Collections.singletonList(credentials.getString(DOMAIN));
+		} else {
+			LOGGER.warn("Neither 'domains' nor 'domain' found in IAS credentials.");
+			return;
+		}
+
+		LOGGER.info("Domains {} found in IAS credentials.", domains);
+		builder.withDomains(domains.toArray(new String[]{}));
+	}
 }

env/src/test/java/com/sap/cloud/security/config/ServiceBindingMapperDomainsTest.java

@@ -0,0 +1,75 @@
+package com.sap.cloud.security.config;
+
+import com.sap.cloud.environment.servicebinding.SapVcapServicesServiceBindingAccessor;
+import com.sap.cloud.environment.servicebinding.api.ServiceBinding;
+import com.sap.cloud.environment.servicebinding.api.ServiceBindingAccessor;
+import nl.altindag.log.LogCaptor;
+import org.apache.commons.io.IOUtils;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests whether ServiceBindingMapper correctly handles 'domains' key in service configurations.
+ * Asserts that both 'domains' values given as String array or as single String value are accepted.
+ * Asserts that 'domain' value given as single String value is also accepted as fall-back for backward compatibility.
+ * Asserts that a warning is printed when no domains are found in an IAS configuration.
+ */
+class ServiceBindingMapperDomainsTest {
+    private static ServiceBinding xsuaaBinding;
+    private static ServiceBinding iasBinding, iasBindingSingleDomain, iasBindingDomainsMissing;
+    private LogCaptor logCaptor;
+
+    @BeforeAll
+    static void setupClass() throws IOException {
+        xsuaaBinding = readServiceBindingFromJson(Service.XSUAA, "/vcapXsuaaServiceSingleBinding.json");
+        iasBinding = readServiceBindingFromJson(Service.IAS, "/vcapIasServiceSingleBinding.json");
+        iasBindingSingleDomain = readServiceBindingFromJson(Service.IAS, "/vcapIasServiceSingleDomain.json");
+        iasBindingDomainsMissing = readServiceBindingFromJson(Service.IAS, "/vcapIasServiceDomainsMissing.json");
+    }
+
+    private static ServiceBinding readServiceBindingFromJson(Service service, String jsonPath) throws IOException {
+        String vcapJson = IOUtils.resourceToString(jsonPath, UTF_8);
+        ServiceBindingAccessor sba = new SapVcapServicesServiceBindingAccessor(any -> vcapJson);
+
+        return sba.getServiceBindings().stream()
+                .filter(b -> service.equals(Service.from(b.getServiceName().orElse(""))))
+                .findFirst().get();
+    }
+
+    @BeforeEach
+    void setup() {
+        logCaptor = LogCaptor.forClass(ServiceBindingMapper.class);
+    }
+
+    @Test
+    void getXsuaaConfiguration() {
+        OAuth2ServiceConfiguration config = ServiceBindingMapper.mapToOAuth2ServiceConfigurationBuilder(xsuaaBinding).build();
+        assertThat(config.getDomains()).isEmpty();
+    }
+
+    @Test
+    void getIasConfiguration() {
+        OAuth2ServiceConfiguration config = ServiceBindingMapper.mapToOAuth2ServiceConfigurationBuilder(iasBinding).build();
+        assertThat(config.getDomains()).containsExactly("myauth.com", "my.auth.com");
+    }
+
+    @Test
+    void getIasConfigurationWithSingleDomain() {
+        OAuth2ServiceConfiguration config = ServiceBindingMapper.mapToOAuth2ServiceConfigurationBuilder(iasBindingSingleDomain).build();
+        assertThat(config.getDomains()).containsExactly("domain1");
+    }
+
+    @Test
+    void getIasConfigurationWithDomainsMissing() {
+        OAuth2ServiceConfiguration config = ServiceBindingMapper.mapToOAuth2ServiceConfigurationBuilder(iasBindingDomainsMissing).build();
+        assertThat(config.getDomains()).isEmpty();
+
+        assertThat(logCaptor.getWarnLogs()).contains("Neither 'domains' nor 'domain' found in IAS credentials.");
+    }
+}

env/src/test/resources/vcapIasServiceDomainsMissing.json

@@ -0,0 +1,20 @@
+{
+  "identity": [
+    {
+      "binding_name": null,
+      "credentials": {
+        "clientsecret": "clientsecret",
+        "clientid": "clientid",
+        "url": "https://myauth.com"
+      },
+      "instance_name": "myservice",
+      "label": "identity",
+      "name": "myservice",
+      "plan": "application",
+      "provider": null,
+      "syslog_drain_url": null,
+      "tags": [],
+      "volume_mounts": []
+    }
+  ]
+}

env/src/test/resources/vcapIasServiceSingleDomain.json

@@ -0,0 +1,21 @@
+{
+  "identity": [
+    {
+      "binding_name": null,
+      "credentials": {
+        "clientsecret": "clientsecret",
+        "clientid": "clientid",
+        "url": "https://myauth.com",
+        "domain" : "domain1"
+      },
+      "instance_name": "myservice",
+      "label": "identity",
+      "name": "myservice",
+      "plan": "application",
+      "provider": null,
+      "syslog_drain_url": null,
+      "tags": [],
+      "volume_mounts": []
+    }
+  ]
+}

java-api/src/main/java/com/sap/cloud/security/config/cf/CFConstants.java

@@ -49,6 +49,10 @@ public static class IAS {
 		private IAS() {
 		}
 
+		/**
+		 * @deprecated in favor of {@link IAS#DOMAINS}
+		 */
+		public static final String DOMAIN = "domain";
 		public static final String DOMAINS = "domains";
 	}