Throwing an exception on invalid syntax in SPRING_APPLICATION_JSON

[pvorb]

As far as I can tell, Spring Boot 2 accepts syntax errors in the SPRING_APPLICATION_JSON environment variable and silently ignores the whole content of the environment variable. This leads to problems that are hard to debug, where properties are not overridden when running an application.

Consider the following example.

application.yml:

parentKey:
    childKey: true

SPRING_APPLICATION_JSON:

{"parentKey" {"childKey": false}}

(Note the missing colon after "parentKey".)

If you now try to inject the value via @Value or a @ConfigurationProperties class, you get true instead of false.

In my opinion it would be better to throw an exception and abort application startup in this case or at least to log an error or warning.

[philwebb]

We currently log a warning but I'm inclined to agree that an exception would be better.

This will be a breaking change so it's not something we can do in a patch release.

[pvorb]

You are right. I missed the warning because of a misconfigured logger.

[philwebb]

Closing in favor of PR #14251