Binding multiple application.yml from working directory to ConfigurationProperties - spring

Question

Starting with Spring Boot 2.4.0, from what I gather from the reference documentation, I should be able to bind multiple application.yaml files from the working directory to ConfigurationProperties:
Wildcard locations are particularly useful in an environment such as Kubernetes when there are multiple sources of config properties.
For example, if you have some Redis configuration and some MySQL configuration, you might want to keep those two pieces of configuration separate, while requiring that both those are present in an application.properties file. This might result in two separate application.properties files mounted at different locations such as /config/redis/application.properties and /config/mysql/application.properties. In such a case, having a wildcard location of config/*/, will result in both files being processed.
By default, Spring Boot includes config/*/ in the default search locations. The means that all subdirectories of the /config directory outside of your jar will be searched.
It is my understanding that the following test case shows that this does not work as described:
Project hierarchy:
config/
first/
application.yaml
second/
application.yaml
src/
main/
kotlin/
test/
Application.kt
test/
kotlin/
test/
TestCase.kt
config/first/application.yaml
composite:
from-first-file:
it: works
config/second/application.yaml
composite:
from-second-file:
it: works
src/main/kotlin/test/Application.kt
#SpringBootApplication(proxyBeanMethods = false)
#EnableConfigurationProperties(CompositeProperties::class)
class Application
fun main(vararg args: String) {
runApplication<Application>(*args)
}
#ConstructorBinding
#ConfigurationProperties("composite")
data class CompositeProperties(
val fromFirstFile: Map<String, String> = mapOf(),
val fromSecondFile: Map<String, String> = mapOf()
)
src/test/kotlin/test/TestCase.kt
#SpringBootTest
class TestCase {
#Autowired
private lateinit var compositeProperties: CompositeProperties
#Test
fun `first file is bound to configuration properties`() {
assertThat(compositeProperties.fromFirstFile).containsEntry("it", "works")
}
#Test
fun `second file is bound to configuration properties`() {
assertThat(compositeProperties.fromSecondFile).containsEntry("it", "works")
}
}
The first test passes, the second one fails. I tried several variations to rule out edge cases and it looks like the second file is completely overlooked. For instance, I tried setting the spring.application.name in the second file and it is not taken into account either.
If this is indeed a bug, is there a workaround I could use until this is fixed?

Answer 1

As I suspected, this is a bug in 2.4.0. Until the problem is fixed, it can be worked around by setting spring.config.use-legacy-processing=true.