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https://issues.apache.org/jira/browse/MJAR-300?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17816696#comment-17816696
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Henning Schmiedehausen commented on MJAR-300:
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[~hboutemy] I looked at the code in maven-archiver, but I am reluctant to use
the archiver; right now I have pretty simple code with a JarOutputStream and
writing JarEntry objects into the stream.
I am using the maven archiver code to parse the output timestamp
([https://github.com/basepom/inline-maven-plugin/blob/main/plugin/src/main/java/org/basepom/inline/mojo/InlineMojo.java#L278)]
and use Instant#toEpochMillis() to write the timestamp. This produces a
different result than the maven archiver "configureReproducibleBuild"
([https://maven.apache.org/shared/maven-archiver/apidocs/org/apache/maven/archiver/MavenArchiver.html#configureReproducibleBuild(java.lang.String)).]
What would be your recommendation? I have no plans to use the JarArchiver or
the complex plexus code. Could we document what plugin writers are *supposed*
to do?
The current behavior seems weird, I am using only standard Java APIs in the
most obvious way and that produces a different result than the archiver code.
(parse Timestamp with maven-archiver -> Instant -> Instant.toEpochMillis()
(which is millis since the epoch in GMT) -> ZipEntry#setTime). Would it make
more sense to use setLastModifiedTime here (which takes a FileTime)?
Also, it would be good to document how the timestamps in the jar are derived
when project.build.outputTimestamp is set. I found next to no documentation
besides code.
> maven jar plugin does not interpret build outputTimestamp correctly
> -------------------------------------------------------------------
>
> Key: MJAR-300
> URL: https://issues.apache.org/jira/browse/MJAR-300
> Project: Maven JAR Plugin
> Issue Type: Bug
> Affects Versions: 3.3.0
> Reporter: Henning Schmiedehausen
> Priority: Major
>
> consider a minimal project that packages a jar:
> % DATE=$(date -Iseconds) ; echo $DATE ; mvn -q clean package ; jar tvf
> target/jartest-0.1-SNAPSHOT.jar
> 2024-02-10T21:44:53-08:00
> 0 Sat Feb 10 21:44:54 PST 2024 META-INF/
> 568 Sat Feb 10 21:44:54 PST 2024 META-INF/MANIFEST.MF
> 0 Sat Feb 10 21:44:54 PST 2024 META-INF/maven/
> 0 Sat Feb 10 21:44:54 PST 2024 META-INF/maven/jartest/
> 0 Sat Feb 10 21:44:54 PST 2024 META-INF/maven/jartest/jartest/
> 5 Sat Feb 10 21:44:54 PST 2024 testfile.txt
> 575 Sat Feb 10 21:39:50 PST 2024 META-INF/maven/jartest/jartest/pom.xml
> 56 Sat Feb 10 21:44:54 PST 2024
> META-INF/maven/jartest/jartest/pom.properties
> Note how the timestamp returned by the date command and the timestamps of the
> entries in the jar are basically the same (around 21:44:53 - 21:44:54 on Feb
> 10th, 2024)
> Now use that date as the project build timestamp:
> DATE=$(date -Iseconds) ; echo $DATE ; mvn -q
> -Dproject.build.outputTimestamp=$DATE clean package ; jar tvf
> target/jartest-0.1-SNAPSHOT.jar
> 2024-02-10T21:46:30-08:00
> 0 Sun Feb 11 05:46:30 PST 2024 META-INF/
> 568 Sun Feb 11 05:46:30 PST 2024 META-INF/MANIFEST.MF
> 0 Sun Feb 11 05:46:30 PST 2024 META-INF/maven/
> 0 Sun Feb 11 05:46:30 PST 2024 META-INF/maven/jartest/
> 0 Sun Feb 11 05:46:30 PST 2024 META-INF/maven/jartest/jartest/
> 5 Sun Feb 11 05:46:30 PST 2024 testfile.txt
> 575 Sun Feb 11 05:46:30 PST 2024 META-INF/maven/jartest/jartest/pom.xml
> 56 Sun Feb 11 05:46:30 PST 2024
> META-INF/maven/jartest/jartest/pom.properties
>
> The timestamp and the entries in the jar differ by eight hours (the offset of
> my local timezone).
> When forcing UTC:
> DATE=$(TZ=UTC date -Iseconds) ; echo $DATE ; mvn -q
> -Dproject.build.outputTimestamp=$DATE clean package ; jar tvf
> target/jartest-0.1-SNAPSHOT.jar
> 2024-02-11T05:48:22+00:00
> 0 Sun Feb 11 05:48:22 PST 2024 META-INF/
> 568 Sun Feb 11 05:48:22 PST 2024 META-INF/MANIFEST.MF
> 0 Sun Feb 11 05:48:22 PST 2024 META-INF/maven/
> 0 Sun Feb 11 05:48:22 PST 2024 META-INF/maven/jartest/
> 0 Sun Feb 11 05:48:22 PST 2024 META-INF/maven/jartest/jartest/
> 5 Sun Feb 11 05:48:22 PST 2024 testfile.txt
> 575 Sun Feb 11 05:48:22 PST 2024 META-INF/maven/jartest/jartest/pom.xml
> 56 Sun Feb 11 05:48:22 PST 2024
> META-INF/maven/jartest/jartest/pom.properties
> The timestamp is "correct" but I passed it in as UTC but the jar plugin
> considers it "local time" and silently attaches PST as timezone. This is
> where the eight hours discrepancy come from.
> This seems to be specific to the outputTimestamp parsing of the jar plugin.
>
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