Hi Julien,
thanks for referencing my repository, hope it helps.
That's an interesting approach. Did you use a generator for the
pom.xml files, and if so how much manual adjustment was required
afterwards?
Yes, I built a crude generator for this based on the output from
`./gradlew [module]:dependencies --configuration compileClasspath` to
get the module dependencies with each other. I think most poms are
unchanged from the generated code. I've uploaded the code as a PR here
<https://github.com/MorMundHS-MA/gradle-maven-bootstrap/pull/2>
On my side I've started to write a Makefile generator that uses Gradle
itself to generate the recipes. It's not finished (and not functional)
yet, but you can get an idea of what the result would look like there [1].
Using a Gradle plugin for this is smart. I wasn't familiar enough with
the ecosystem to attempt that, but with Gradle/Maven plugins you can
probably get to a fully automated/reproducible conversion.
Not sure if Makefiles will be a good choice, as the project is large
with a lot of dependencies between the modules. The generated poms are
easily reviewable by a human, I think this will be much harder with
Makefiles. But maybe I'm overthinking the supply chain trust issues with
bootstrapping build tools.
The generator is the MakefileMaker class at the bottom of [2]. I'm
planning to add custom logic to generate the additional code and
properties at (re)build time. The idea is to have something reasonably
simple that could be used to bootstrap a future version with minimal
or no changes (ideally) to the generation logic.
I was hoping that bootstrapping one modern version of Gradle/Kotlin
would be enough to build future versions using the tooling itself. But I
don't know how commonly they still introduce new functionality/breaking
changes that would prevent building with older versions.
They still use Kotlin 2.0.21 currently, setting the source
compatibility to 1.9 (or 1.8 maybe?) to force the use of the legacy K1
compiler, and adding another legacy dependency as they use APIs that
are now deprecated and even removed for some. It's possible to compile
the Kotlin code using older compilers (with a few minor adjustments
eventually) but the Kotlin scripting integration (DSL) in Gradle is
much less likely to be buildable or work with older versions of Kotlin
compiler libraries without some extensive changes.
Which version of Kotlin has been bootstrapped? I think Debian had 1.3 at
some point, but I'm not sure if that was completely built from source.
At least it isn't available in testing anymore.
So far the only other dependencies I found that will need to be
bootstrapped in the same batch (with gradle and kotlin) are:
Gradle also references these dependencies that are built with Gradle
(list won't be complete, just the obvious ones):
* kotlin-stdlib
* kotlin-reflect
* kotlinx-serialization-core
* kotlinx-serialization-json
* kotlin-compiler-embeddable (dependency of
'gradle-declarative-dsl-core', probably the biggest one together with
stdlib as it requires a modern bootstrapped kotlin compiler)
* org.jetbrains.annotations
* org.jetbrains.intellij.deps.trove4j
There is also one additional Gradle repository, which I cannot find
right now. But I had to downgrade its version manually as the Gradle
devs hadn't uploaded their newest version to a public registry yet when
I was working on it. But it was also built with Gradle.
Best,
Moritz
On 17.03.2025 10:42, Julien Plissonneau Duquène wrote:
Hi Moritz,
Le 2025-03-16 11:10, Moritz a écrit :
I got interested in the problem of bootstrapping a modern versions of
Gradle, mainly due to the old version available in Debian. As far as
I can tell, efforts have been mostly focused on using older versions
to bootstrap an up-to-date version.
Most but not all. My own branch also uses the same version of Gradle
to rebuild itself.
I wanted to explore the feasibility and effort required to bootstrap
with Maven instead. I now have a working purely Maven-based build
that generates a distribution capable of building Gradle itself. The
code is available here
<https://github.com/MorMundHS-MA/gradle-maven-bootstrap>.
That's an interesting approach. Did you use a generator for the
pom.xml files, and if so how much manual adjustment was required
afterwards?
On my side I've started to write a Makefile generator that uses Gradle
itself to generate the recipes. It's not finished (and not functional)
yet, but you can get an idea of what the result would look like there
[1]. The generator is the MakefileMaker class at the bottom of [2].
I'm planning to add custom logic to generate the additional code and
properties at (re)build time. The idea is to have something reasonably
simple that could be used to bootstrap a future version with minimal
or no changes (ideally) to the generation logic.
While it was fun, I am not sure how much this actually helps as it
still requires a pre-build Kotlin compiler (at least 1.8 I think,
even though >2.0 is used). Additionally some of the other
dependencies are also built with Gradle and would have to be
bootstrapped as well. But I wanted to share my progress so far non
the less.
They still use Kotlin 2.0.21 currently, setting the source
compatibility to 1.9 (or 1.8 maybe?) to force the use of the legacy K1
compiler, and adding another legacy dependency as they use APIs that
are now deprecated and even removed for some. It's possible to compile
the Kotlin code using older compilers (with a few minor adjustments
eventually) but the Kotlin scripting integration (DSL) in Gradle is
much less likely to be buildable or work with older versions of Kotlin
compiler libraries without some extensive changes.
So far the only other dependencies I found that will need to be
bootstrapped in the same batch (with gradle and kotlin) are:
- kotlinx.serialization
- kotlinx-metadata-jvm 0.5.0 (Kotlin 1.8.10 is the last release with
that version).
Thank you for sharing this. I will add a link to your repository on my
own wip/README.
Cheers,
[1]:
https://salsa.debian.org/jpd/gradle/-/blob/478abafcd391cc28549f9b369d7b42a3febb3197/debian/gradle.Makefile
[2]:
https://salsa.debian.org/jpd/gradle/-/blob/478abafcd391cc28549f9b369d7b42a3febb3197/debian/init.d/gradlebuild/DebianGradleBuildPlugin.gradle#L638
