RFR: 8264449: Enable reproducible builds with SOURCE_DATE_EPOCH [v5]

[John Neffenger]

On Mon, 14 Jun 2021 20:53:50 GMT, John Neffenger <jgneff at openjdk.org> wrote:

>> This pull request allows for reproducible builds of JavaFX on Linux, macOS, and Windows by defining the `SOURCE_DATE_EPOCH` environment variable. For example, the following commands create a reproducible build:
>> 
>> 
>> $ export SOURCE_DATE_EPOCH=$(git log -1 --pretty=%ct)
>> $ bash gradlew sdk jmods javadoc
>> $ strip-nondeterminism -v -T $SOURCE_DATE_EPOCH build/jmods/*.jmod
>> 
>> 
>> The three commands:
>> 
>> 1. set the build timestamp to the date of the latest source code change,
>> 2. build the JavaFX SDK libraries, JMOD archives, and API documentation, and
>> 3. recreate the JMOD files with stable file modification times and ordering.
>> 
>> The third command won't be necessary once Gradle can build the JMOD archives or the `jmod` tool itself has the required support. For more information on the environment variable, see the [`SOURCE_DATE_EPOCH`][1] page. For more information on the command to recreate the JMOD files, see the [`strip-nondeterminism`][2] repository. I'd like to propose that we allow for reproducible builds in JavaFX 17 and consider making them the default in JavaFX 18.
>> 
>> #### Fixes
>> 
>> There are at least four sources of non-determinism in the JavaFX builds:
>> 
>> 1. Build timestamp
>> 
>>     The class `com.sun.javafx.runtime.VersionInfo` in the JavaFX Base module stores the time of the build. Furthermore, for builds that don't run on the Hudson continuous integration tool, the class adds the build time to the system property `javafx.runtime.version`.
>> 
>> 2. Modification times
>> 
>>     The JAR, JMOD, and ZIP archives store the modification time of each file.
>> 
>> 3. File ordering
>> 
>>     The JAR, JMOD, and ZIP archives store their files in the order returned by the file system. The native shared libraries also store their object files in the order returned by the file system. Most file systems, though, do not guarantee the order of a directory's file listing.
>> 
>> 4. Build path
>> 
>>     The class `com.sun.javafx.css.parser.Css2Bin` in the JavaFX Graphics module stores the absolute path of its `.css` input file in the corresponding `.bss` output file, which is then included in the JavaFX Controls module.
>> 
>> This pull request modifies the Gradle and Groovy build files to fix the first three sources of non-determinism. A later pull request can modify the Java files to fix the fourth.
>> 
>> [1]: https://reproducible-builds.org/docs/source-date-epoch/
>> [2]: https://salsa.debian.org/reproducible-builds/strip-nondeterminism
>
> John Neffenger has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
> 
>  - Make build of SDK ZIP bundle reproducible
>  - Merge branch 'master' into allow-reproducible-builds
>  - Merge branch 'master' into allow-reproducible-builds
>  - Include WebKit shared library for Windows
>    
>    Enable reproducible builds of the native WebKit shared library for
>    Windows (jfxwebkit.dll) when SOURCE_DATE_EPOCH is defined.
>  - Include media shared libraries for Windows
>    
>    Enable reproducible builds of the native media shared libraries for
>    Windows when SOURCE_DATE_EPOCH is defined. The libraries are:
>    
>      fxplugins.dll
>      glib-lite.dll
>      gstreamer-lite.dll
>      jfxmedia.dll
>  - Enable reproducible builds with SOURCE_DATE_EPOCH
>  - 8238650: Allow to override buildDate with SOURCE_DATE_EPOCH

> 1. On all three platforms the results are the same: All files were identical except the native jfxwebkit library.

The [diffoscope][1] tool can show you the difference between the two files. You don't even need to install it. If the files aren't too big, you can upload them to the [online version][2].

> 2. On Mac, at least, there are several differences in the dylib files between a build on my local system and on our CI system.

I would like to enable reproducible builds on ephemeral systems that create a clean and isolated build environment, like those created by GitHub Actions or the Launchpad build farm. To compare across developer systems, we would need a full system software bill of materials (SBOM) beyond what's listed in the Gradle dependency verification file. The SBOM is the next step in allowing for reproducible builds in any environment, but it's not a part of this pull request.

[1]: https://diffoscope.org/
[2]: https://try.diffoscope.org/

-------------

PR: https://git.openjdk.java.net/jfx/pull/446