SERVER_HOME environment variable prevents Spring Boot from starting with M4

[snicoll]

This is kind of related to #3427 but in a different way.

For some reason, SERVER_HOME was not processed by Spring Boot up to 1.3.0.M3. Since M4, it is now processed and this leads to the following:

org.springframework.beans.NotWritablePropertyException: Invalid property 'HOME' of bean class [org.springframework.boot.autoconfigure.web.ServerProperties]: Bean property 'HOME' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?

The weird thing here is that it is "expected" as anything that is not known by ServerProperties should blow up. But for some reason having a SERVER_HOME OS env works just fine except with 1.3.0.M4

Maybe we have users out there that have such property and didn't notice so far. This makes #3427 even more relevant.

Steps to reproduce: create a app from start.spring.io with the web starter, export a SERVER_HOME OS env and run.

[wilkinsona]

I'm not sure that this is a regression. I'd argue that we've actually fixed a long-standing bug where ignoreUnknownProperties = false wasn't being honoured. A new minor version feels like a reasonable place to fix such a bug, i.e. I don't think we should change 1.2.x.

[sbrannen]

@wilkinsona, if you don't consider this a regression, the way that boot blows up should be at least somewhere in the vicinity of user friendly.

@snicoll actually raised this issue for me.

I've had a SERVER_HOME environment variable on my system for quite some time (think Virgo 😉).

As it stands now, I have an app that worked against boot 1.2.x and all 1.3.0 milestones thus far. Then I upgraded to 1.3.0 M4, and boom:

java.lang.IllegalStateException
    Caused by: org.springframework.context.ApplicationContextException
        Caused by: org.springframework.beans.factory.BeanCreationException
            Caused by: org.springframework.beans.factory.BeanCreationException
                Caused by: org.springframework.beans.factory.BeanCreationException
                    Caused by: org.springframework.beans.factory.BeanCreationException
                        Caused by: org.springframework.beans.NotWritablePropertyException

[sbrannen]

After digging deeper, I come a cross a 121 line stack trace, which in the end only tells me:

Caused by: org.springframework.beans.NotWritablePropertyException: Invalid property 'HOME' of bean class [org.springframework.boot.autoconfigure.web.ServerProperties]: Bean property 'HOME' is not writable or has an invalid setter method. Does the parameter type of the setter match the return type of the getter?
    at org.springframework.beans.BeanWrapperImpl.createNotWritablePropertyException(BeanWrapperImpl.java:229)
    at org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue(AbstractNestablePropertyAccessor.java:423)
    at org.springframework.beans.AbstractNestablePropertyAccessor.setPropertyValue(AbstractNestablePropertyAccessor.java:280)
    at org.springframework.beans.AbstractPropertyAccessor.setPropertyValues(AbstractPropertyAccessor.java:95)
    at org.springframework.validation.DataBinder.applyPropertyValues(DataBinder.java:810)
    at org.springframework.validation.DataBinder.doBind(DataBinder.java:706)
    at org.springframework.boot.bind.RelaxedDataBinder.doBind(RelaxedDataBinder.java:123)
    at org.springframework.validation.DataBinder.bind(DataBinder.java:691)
    at org.springframework.boot.bind.PropertiesConfigurationFactory.doBindPropertiesToTarget(PropertiesConfigurationFactory.java:259)
    at org.springframework.boot.bind.PropertiesConfigurationFactory.bindPropertiesToTarget(PropertiesConfigurationFactory.java:233)
    at org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor.postProcessBeforeInitialization(ConfigurationPropertiesBindingPostProcessor.java:298)
    ... 91 more

There is zero mention of the SERVER_HOME environment variable that caused the problem.

So how should an unsuspecting/uninformed user come up with the idea that his SERVER_HOME environment variable -- which has been on his system literally for years and never adversely affected any application -- now all of a sudden is the reason that Spring Boot 1.3.0 M4 doesn't work, even for bare bones web apps created by the Spring Starter app?

[wilkinsona]

Thanks for the feedback, @sbrannen. Note that I was only making the case for this not being classed as a regression. I was not making a case for doing nothing to address the issue.

I think the point that you've made about the diagnostics for a binding failure is a good one. The problem's actually broader than this issue. For example, A SERVER_PORT environment variable with a strange or mistyped value with also cause a hard-to-diagnose failure. I've opened #3778.

[sbrannen]

@wilkinsona, thanks for opening #3778!

Improving the diagnostics is the very least that should be done in this regard.

[madorb]

I am seeing this same sort of issue in M4 with liquibase. Opened #3797 - looks to be due to having LIQUIBASE_HOME set. Some sort of more user friendly error / mentions in documentation would be much appreciated

[snicoll]

@madorb check also #3778