CloudPlatform.isActive can return true when spring.main.cloud-platform is set to NONE

[nguyensach]

Fixes #25433

add isAutoDetectionEnabled method to determine that whether it is enabled that the platform is detected by looking for platform-specific environment variables.

[wilkinsona]

Thanks for the pull request, @nguyensach. An alternative approach would be to change the condition. It could get the active CloudPlatform and see if it matches the required platform rather than checking if the required platform is active. I think I prefer what you've proposed here but I want to check with the team to see if the current behaviour of CloudPlatform is intentional. The follow code is in ConfigDataActivationContext:

spring-boot/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataActivationContext.java

Lines 58 to 65 in 59d8c97

	private CloudPlatform deduceCloudPlatform(Environment environment, Binder binder) {
	for (CloudPlatform candidate : CloudPlatform.values()) {
	if (candidate.isEnforced(binder)) {
	return candidate;
	}
	}
	return CloudPlatform.getActive(environment);
	}

It's making me wonder if there are some subtleties here that I'm overlooking. By calling isEnforced on each CloudPlatform and then falling back to getActive it seems to be allowing a CloudPlatform to be enforced ahead of an earlier one that would have been detected as active.

[nguyensach]

@wilkinsona Thanks for your response. I think that the code in ConfigDataActivationContext is right. When deduceCloudPlatform method is called, there is not actived profile.

spring-boot/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/config/ConfigDataActivationContext.java

Lines 37 to 38 in 59d8c97

	* Create a new {@link ConfigDataActivationContext} instance before any profiles have
	* been activated.

Therefore, All CloudPlatform#isEnforced(environment) will be false.

[philwebb]

Thanks very much @nguyensach for contributing to Spring Boot. This is now in 2.3.x, 2.4.x and 2.5.x