Rework PropertySourceBootstrapConfiguration to update the environment during environment post-processing and before ApplicationEnvironmentPreparedEvent is published

[wilkinsona]

At the moment, PropertySourceBootstrapConfiguration is triggered by BootstrapApplicationListener on ApplicationEnvironmentPreparedEvent at which point it makes changes to the Environment. This breaks the expected lifecycle of the environment as no changes are expected after the environment has been prepared. It will hopefully be possible to correct this by switching to an EnvironmentPostProcessor. This should fix spring-projects/spring-boot#18191. It should also allow the code that reinitialises the logging system – something that has caused numerous bugs over the years – to be removed.

If there's anything we can do in Boot or any assistance we can provide on the Cloud side to help to make this happen, please let us know.

[spencergibb]

Ping @dsyer

[dsyer]

Makes sense to look at it. I have a feeling that an ApplicationListener might need to be retained to do some sloshing of parent-child context relationships, but the bulk of the work with the Environment could go into an EnvironmentPostProcessor.

[cschockaert]

Any update on this ticket? we are missing that feature a lot

[spencergibb]

No