Bug#1039607: libjansi-java: causes maven to always output escape character

[tony mancill]

On Thu, Jan 04, 2024 at 10:22:02PM -0800, tony mancill wrote:
> However, for the short-term, I believe we can achieve the desired
> behavior and fix the issue for most use cases by
> 
> 1. Patching the mvn wrapper script in our maven package to set
> jansi.mode=force (and thus colorize output) unless the --batch-mode
> option is provided.
> 
> 2. Moving forward with the current jansi package in experimental.
> 
> That restores the desired --batch-mode behavior but maintains
> colorized output by default and during Debian package builds.

I am preparing an upload of maven to experimental (version 3.8.7-2~exp1)
that implements the changes described above.  I will push the packaging
changes to the debian/experimental branch in the Salsa repo.  The patch
for mvn can be found here:

https://salsa.debian.org/java-team/maven/-/blob/4501966b3678135deacca45bc1a918380f6dac47/debian/patches/03_jansi_behavior.patch

When used in conjunction with the jansi package in experimental, the
behavior is:

**output is colorized**
mvn

**output is non-colorized**
mvn -B
mvn --batch-mode

The patched mvn script also checks for MAVEN_JANSI_PROPERTY in the
environment, which allows users to override the behavior if desired.
I don't expect this to be needed very often, but it may be useful if
we modify the behavior of jansi in the future, and I wanted there to
be an escape valve if the patched behavior is problematic for some
unforeseen use case.

The invocations below demonstrate the behavior of Debian's jansi that
led to the patch in 2.4.0-2, i.e., that without the native jansi
libraries or -Djansi.mode=force, the default TTY detection fails and
results in non-colorized output.

MAVEN_JANSI_PROPERTY="" mvn
MAVEN_JANSI_PROPERTY= mvn

For completeness:

MAVEN_JANSI_PROPERTY="-Djansi.mode=default" mvn  --> non-colorized
MAVEN_JANSI_PROPERTY="-Djansi.mode=strip" mvn    --> non-colorized
MAVEN_JANSI_PROPERTY="-Djansi.mode=force" mvn    --> colorized

With these changes, we shouldn't need the patched maven-debian-helper I
proposed previously, since the output of Maven invoked during builds
will be colorized.

I believe this will address the issues reported in
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1039607 and
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1059147

Feedback welcome.  We can coordinate here before any migrations from
experimental to unstable.

Thanks,
tony
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