Merge pull request #25829 from jdubois

* gh-25829:
  Polish "Add detection of Azure App Service to CloudPlatform"
  Add detection of Azure App Service to CloudPlatform

Closes gh-25829

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

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -130,6 +130,23 @@ public enum CloudPlatform {
 			return false;
 		}
 
+	},
+
+	/**
+	 * 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);
+		}
+
 	};
 
 	private static final String PROPERTY_NAME = "spring.main.cloud-platform";

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

 /*
- * Copyright 2012-2020 the original author or authors.
+ * Copyright 2012-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,7 +50,6 @@ class CloudPlatformTests {
 		Environment environment = new MockEnvironment();
 		CloudPlatform platform = CloudPlatform.getActive(environment);
 		assertThat(platform).isNull();
-
 	}
 
 	@Test
@@ -131,6 +130,32 @@ class CloudPlatformTests {
 		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 getActiveWhenHasWebsiteSiteNameAndNoWebsitesEnableAppServiceStorageShouldNotReturnAzureAppService() {
+		Environment environment = getEnvironmentWithEnvVariables(Collections.singletonMap("WEBSITE_SITE_NAME", "---"));
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNull();
+	}
+
+	@Test
+	void getActiveWhenHasWebsitesEnableAppServiceStorageAndNoWebsiteNameShouldNotReturnAzureAppService() {
+		Environment environment = getEnvironmentWithEnvVariables(
+				Collections.singletonMap("WEBSITES_ENABLE_APP_SERVICE_STORAGE", "---"));
+		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNull();
+	}
+
 	@Test
 	void getActiveWhenHasEnforcedCloudPlatform() {
 		Environment environment = getEnvironmentWithEnvVariables(