4.x: MP Config does not correctly handling per property overriding with config profiles

[barchetta]

Environment Details

• Helidon Version: 4.0.8
• Helidon MP

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Problem Description

Helidon MP Config is not correctly handling per property overriding precedence when config profiles (spec) are used. Note that this is not a change from the MP Config 3.0 spec -- just a clarification.

The proper behavior is that a profile-specific property only overrides the vanilla property per config source. Therefore if I specify the vanilla property in a config source with a high ordinal, it should trump any profile specific property from a config source at a lower ordinal. Our implementation appears to always place a higher precedence on the profile-specific property. Looks like this is the problematic code:

helidon/config/config-mp/src/main/java/io/helidon/config/mp/MpConfigImpl.java

Line 114 in a905313

return findConfigValue("%" + configProfile + "." + key)

helidon/config/config-mp/src/main/java/io/helidon/config/mp/MpConfigImpl.java

Line 133 in a905313

return optionalValue("%" + configProfile + "." + propertyName, propertyType)

Steps to reproduce

You can run the MP Config 3.1 TCK. See #8724. Or

1. Create the MP quickstart using the Helidon CLI
2. Add this line to microprofile-config.properties: %dev.app.greeting=Yo
3. Build then Run the application with java -Dmp.config.profile=dev -Dapp.greeting=Hola -jar target/quickstart-mp.jar
4. Do curl -X GET http://localhost:8080/greet

You'll see the application returns the property from the dev profile which is incorrect:

{"message":"Yo World!"}

According to the spec (and the 3.1 TCKs) it should return the value from the system property (Hola) since that ConfigSource has a higher ordinal.

[barchetta]

The fix to this issue might depend on #8737 getting fixed.