Convert Gradle config parameters (such as jib.container.labels) to use lazy evaluation

Just like there was an issue to make the jib.to.tags and jib.to.auth to be lazyly evaluated I would need to have the container.labels do the same. Even the reason is the same. I use com.gorylenko.gradle-git-properties Gradle plugin and would like to reuse its properties to add labels to my images. Something like that:

jib {
    container {
        labels = [
            'org.label-schema.vcs-url': project.ext.gitProps['git.remote.origin.url'],
            'org.label-schema.vcs-branch': project.ext.gitProps['git.branch'],
            'org.label-schema.vcs-ref': project.ext.gitProps['git.commit.id.abbrev']
        ]
    }
}

In our case I would make that configuration global and add this snipped to our custom gradle wrapper init script.

I did try something like this:

jib
    container {
        labels = [
            ...
            'org.label-schema.vcs-ref': "${-> project.ext.gitProps['git.commit.id.abbrev']}"
        ]
    }
}

But this errored out with this message: > class org.codehaus.groovy.runtime.GStringImpl cannot be cast to class java.lang.String (org.codehaus.groovy.runtime.GStringImpl is in unnamed module of loader org.gradle.internal.classloader.VisitableURLClassLoader @47c62251; java.lang.String is in module java.base of loader 'bootstrap')

[chanseokoh]

@remy-tiitre @ChristianCiach @NaitYoussef Jib 3.1.1 is released with this support. Let us know if it doesn’t work.

[chanseokoh]

@NaitYoussef thanks for your interest!

As noted in https://github.com/GoogleContainerTools/jib/issues/3094#issuecomment-788064416,

• Going forward, we decided to expose Property<?> in this particular way (#3034 and #3121) for new parameters. And perhaps this is not possible with existing parameters for compatibility reasons. (Could be revamped in a major version change.)

the way we decided to expose Gradle properties is to use Property<?> like this. That is, no setters but a getter will directly expose a Property<?>.

This GitHub issue is about jib.container.labels, so my guess is that this property labels should be changed to be of type MapProperty. This may not be fully backward-compatible, but I think should be fine most of the time.