Add detection of Azure App Service to CloudPlatform

See gh-25829

Author: jdubois

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

@@ -45,6 +45,23 @@ public boolean isDetected(Environment environment) {
 
 	},
 
+	/**
+	 * Azure App Service platform.
+	 */
+	AZURE_APP_SERVICE {
+
+		private static final String WEBSITE_SITE_NAME = "WEBSITE_SITE_NAME";
+
+		private static final String WEBSITES_ENABLE_APP_SERVICE_STORAGE = "WEBSITES_ENABLE_APP_SERVICE_STORAGE";
+
+		@Override
+		public boolean isDetected(Environment environment) {
+			return environment.containsProperty(WEBSITE_SITE_NAME)
+					&& environment.containsProperty(WEBSITES_ENABLE_APP_SERVICE_STORAGE);
+		}
+
+	},
+
 	/**
 	 * Cloud Foundry platform.
 	 */

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

@@ -50,7 +50,33 @@ void getActiveWhenNotInCloudShouldReturnNull() {
 		Environment environment = new MockEnvironment();
 		CloudPlatform platform = CloudPlatform.getActive(environment);
 		assertThat(platform).isNull();
+	}
+
+	@Test
+	void getActiveWhenHasWebsiteSiteNameAndWebsitesEnableAppServiceStorageShouldReturnAzureAppService() {
+		Map<String, Object> envVars = new HashMap<>();
+		envVars.put("WEBSITE_SITE_NAME", "---");
+		envVars.put("WEBSITES_ENABLE_APP_SERVICE_STORAGE", "false");
+		Environment environment = getEnvironmentWithEnvVariables(envVars);
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isEqualTo(CloudPlatform.AZURE_APP_SERVICE);
+		assertThat(platform.isActive(environment)).isTrue();
+	}
+
+	@Test
+	void getActiveWhenHasWebsiteSiteNameShouldReturnNull() {
+		Environment environment = getEnvironmentWithEnvVariables(
+				Collections.singletonMap("WEBSITE_SITE_NAME", "---"));
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNull();
+	}
 
+	@Test
+	void getActiveWhenHasWebsitesEnableAppServiceStorageShouldReturnNull() {
+		Environment environment = getEnvironmentWithEnvVariables(
+				Collections.singletonMap("WEBSITES_ENABLE_APP_SERVICE_STORAGE", "---"));
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNull();
 	}
 
 	@Test