RFR: 8276743: Make openjdk build Zip Archive generation "reproducible"

[Magnus Ihse Bursie]

On Tue, 9 Nov 2021 17:28:39 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

>> This PR adds a new openjdk build tool GenerateZip, which generates a final "zip" file from an input folder, and creates it in a deterministic way, ensuring ordering and timestamps are set as specified.
>> 
>> Using this tool in ZipArchive.gmk will ensure src.zip is then created deterministically.
>> 
>> Signed-off-by: Andrew Leonard <anleonar at redhat.com>
>
> I agree that ideally reproducibility should be on by default, but if there is a cost, then you can be sure OpenJDK developers will be looking for a way to remove it for faster turnaround times. I would propose a specific configure parameter for this specific case, reproducible zip files, that is default on for release builds and off for debug builds (debug builds aren't reproducible by nature) and let the existing meta flag also control the value of this new flag.

@erikj79 The flag --enable-reproducible-builds sets ENABLE_REPRODUCIBLE_BUILD in spec.gmk. This is set by our JIB profiles. I propose that we also turn it on for GHA builds. 

I think that the post-processing of the zip file can be dependent on this variable and that it serves no purpose to introduce a separate variable ENABLE_REPRODUCIBLE_ZIP that is set to the same value as ENABLE_REPRODUCIBLE_BUILD. Do you agree?

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PR: https://git.openjdk.java.net/jdk/pull/6311