Use more precise variables to detect Azure App Service

See gh-27819

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/cloud/CloudPlatform.java

@@ -140,12 +140,17 @@ public enum CloudPlatform {
 
 		private static final String WEBSITE_SITE_NAME = "WEBSITE_SITE_NAME";
 
-		private static final String WEBSITES_ENABLE_APP_SERVICE_STORAGE = "WEBSITES_ENABLE_APP_SERVICE_STORAGE";
+		private static final String WEBSITE_INSTANCE_ID = "WEBSITE_INSTANCE_ID";
+
+		private static final String WEBSITE_RESOURCE_GROUP = "WEBSITE_RESOURCE_GROUP";
+
+		private static final String WEBSITE_SKU = "WEBSITE_SKU";
 
 		@Override
 		public boolean isDetected(Environment environment) {
-			return environment.containsProperty(WEBSITE_SITE_NAME)
-					&& environment.containsProperty(WEBSITES_ENABLE_APP_SERVICE_STORAGE);
+			return environment.containsProperty(WEBSITE_SITE_NAME) && environment.containsProperty(WEBSITE_INSTANCE_ID)
+					&& environment.containsProperty(WEBSITE_RESOURCE_GROUP)
+					&& environment.containsProperty(WEBSITE_SKU);
 		}
 
 	};

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/cloud/CloudPlatformTests.java

@@ -136,7 +136,9 @@ class CloudPlatformTests {
 	void getActiveWhenHasWebsiteSiteNameAndWebsitesEnableAppServiceStorageShouldReturnAzureAppService() {
 		Map<String, Object> envVars = new HashMap<>();
 		envVars.put("WEBSITE_SITE_NAME", "---");
-		envVars.put("WEBSITES_ENABLE_APP_SERVICE_STORAGE", "false");
+		envVars.put("WEBSITE_INSTANCE_ID", "1234");
+		envVars.put("WEBSITE_RESOURCE_GROUP", "test");
+		envVars.put("WEBSITE_SKU", "1234");
 		Environment environment = getEnvironmentWithEnvVariables(envVars);
 		CloudPlatform platform = CloudPlatform.getActive(environment);
 		assertThat(platform).isEqualTo(CloudPlatform.AZURE_APP_SERVICE);