( short link: https://s.apache.org/reproducible-builds )
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see also the Maven - Guide to Configuring for Reproducible Builds |
Context
https://reproducible-builds.org/ (see mailing list)
Reproducible builds are a set of software development practices that create a verifiable path from human readable source code to the binary code used by computersHow?
First, the build system needs to be made entirely deterministic: transforming a given source must always create the same result. Typically, the current date and time must not be recorded and output always has to be written in the same order.
Second, the set of tools used to perform the build and more generally the build environment should either be recorded or pre-defined.
Third, users should be given a way to recreate a close enough build environment, perform the build process, and verify that the output matches the original build.
...
But Maven plugins in the whole ecosystem (not only provided by Apache Maven team) sometimes add some variable parts that adds to the problem: timestamp text or username in MANIFEST.MF, ...
In 2015, reproducible-build-maven-plugin has been created to try to fix issues after packaging, by rewriting the archive and reworking content known for variable parts.
The goal of this proposal started in 2017 is to prepare a set of configuration and practices to have reproducible/verifiable builds at packaging time, both by enhancing java natural build behaviour and by removing some variability introduced by some Maven plugins (core plugins at first, but also in the Maven eco-system).
In parallel to this proposal, "Reproducible Maven Builds" site has been created to work on prototypes.
...
- Timestamps:
- Timestamps in ZIP/JAR files: file last modification time/date in central directory and file entry headers + possible optional fields "X5455_ExtendedTimestamp" (PLEXUS-ARCHIVER-48plexus-archiver PR #121)
- Timestamp in pom.properties generated by maven-archiver (MSHARED-494
)
- Timestamp in plugin.xml and plugin-help.xml descriptors generated by maven-plugin-tools-generator (MPLUGIN-326
)
- Timestamp in MANIFEST.MF (Bnd-LastModified) generated by Felix maven-bundle-plugin
- Timestamps in generated javadoc HTML files (can be disabled with javadoc options "notimestamp" and "bottom")
- Timestamps in bytecode generated from Groovy code (added by GroovyClassLoader.addTimeStamp())
- Username:
- UID/GID in tar file entries
- Username in MANIFEST.MF (Built-By) generated by maven-archiver (MSHARED-661
)
- Ordering:
- Order of the file entries in a ZIP/JAR file (depends on file system order)
- Order of the entries in the MANIFEST (MSHARED-511
)
- Order of goals in plugin.xml generated by maven-plugin-tools (MPLUGIN-261
)
- Order of the methods of the ObjectFactory.java file generated by JAXB/xjc (JAXB-598
)
- Order of components in META-INF/plexus/components.xml generated by plexus metadata (issue #8
)
- Tools Versions:
- exact JDK version used to build in MANIFEST.MF (Build-Jdk) generated by maven-archiver (MSHARED-797
)
Notice that keeping the major version of the JDK used still makes sense, since it has an influence on generated bytecode: with the same source code and defined -target version, javac from JDK 6, 7, 8, ... do not produce the same bytecode. If we want to isolate the generated binary from JDK used, the compiler used will have to not be javac provided by running JDK (see Using Non-Javac Compilers) - exact Maven version used to build in MANIFEST.MF (Created-By) generated by maven-archiver (MSHARED-799
)
- exact Maven version used to build in META-INF/.../pom.properties generated by maven-archiver (MSHARED-800
)
- exact JDK version used to build in MANIFEST.MF (Build-Jdk) generated by maven-archiver (MSHARED-797
...
Life would become easier if there was a dedicated POM element like ${project.build.outputTimestamp}
(with an ISO - 8601 formatted date+time) which could be used to specify the timestamp value once per entire project. Every plugin could use it as default value, like it has been done with source files encoding:
...
What are the issues to solve?
issue tracking | description | ||
---|---|---|---|
MSHARED-661 ( |
| maven-archiver adds "Built-By: <username>" Manifest entry: the entry was removed | |
MSHARED-796 ( | META-INF/MANIFEST.MF | maven-archiver adds "Built-Jdk: <detailed java version>" Manifest entry: better replaced with "Built-Jdk: <java specification version>"||
MSHARED-494 ( | META-INF/maven/$groupId/$artifactId/pom.properties | Timestamp in pom.properties | |
MSHARED-800 | META-INF/maven/$groupId/$artifactId/pom.properties | Maven version in pom.properties | |
MPLUGIN-261 ( | META-INF/maven/plugin.xml | generated plugin.xml | is non-deterministic|
MPLUGIN-326 ( | META-INF/maven/plugin.xml META-INF/maven/$groupId/$artifactId/plugin-help.xml | Timestamp in plugin.xml and plugin-help.xml descriptors generated by maven-plugin-tools-generator||
plexus-containers issue #8 ( | META-INF/plexus/components.xml | sort components when generating ||
plexus | /components.xmlplexus-containers issue #27 ( | META-INF/plexus/components.xml | sort components when merging discovered components with manually crafted component files|
bnd-maven-plugin #3521 ( | META-INF/MANIFEST.MF | "Private-Package" manifest entry content (created by felix:bundle) has not the same order between builds | |
sisu-maven-plugin PR#5 ( | META-INF/sisu/javax.inject.NamedMANIFEST.MF | ||
FELIX-6203 ( | META-INF/maven/$groupId/$artifactId/pom.properties | ||
sisu-maven-plugin 5e2377c ( | META-INF/sisu/javax.inject.Named | content (created by ||
sisu-maven-plugin | ) has non reproducible order for content|||
zip entries timestamp and order | |||
COMPRESS-485 ( | keep entries order when gathering ParallelScatterZipCreator | ||
annotation processor 570e81 ( | META-INF/sisu/javax.inject.Named | ||
MRRESOURCES-114 ( | projectTimespan, as often printed in META-INF/NOTICE | ||
JDK-8240734 ( | module-info.class | ||
zip entries timestamp and order | |||
COMPRESS-485 ( | keep entries order when gathering ParallelScatterZipCreator | ||
plexus-archiver ( 0): predefined timestamp | avoid timestamp issues in archives created by plexus-archiver (widely used in Maven plugins creating jar, zip, war, tar... archives) | ||
plexus-archiver issue #114 ( | To enable reproducible builds `AbstractArchiver#addFileSet` should add the files in order | ||
MSHARED-837 ( | support => see "Output Archive Entries Timestamp" section of the proposal | ||
plexus-archiver #271 ( | remove variation based on user's umask on Unixes (particularly group write) | ||
plexus-archiver #124 ( | remove variation based on uid/gid & userName/groupName in tar | ||
MSOURCES-120 ( | apply reproducible zip (entries order and timestamp) to maven-source-plugin | ||
MSOURCES- | 921137 ( | apply 022 umask (to ease RB check: independent from env) | |
MASSEMBLY-921 ( | apply reproducible archive (entries order and timestamp) to maven-assembly-plugin | ||
MASSEMBLY-989 ( | apply 022 umask (to ease RB check: independent from env) | ||
MJAR-263 ( | apply reproducible zip (entries order and timestamp) to maven-jar-plugin | ||
MSITE-851 ( | apply reproducible zip (entries order and timestamp) to site:jar | ||
MJAVADOC-627 ( | apply reproducible zip (entries order and timestamp) to javadoc:*jar | ||
MSHADE-347 ( | apply reproducible zip (entries order and timestamp) to shade:shade | ||
MSHADE-352 ( | keep reproducible timestamp when shading with transformer | ||
MSHADE-420 | mtime from extra field data from shaded dependency makes result builder's timezone sensitive | ||
ARCHETYPE-590 ( | apply reproducible zip (entries order and timestamp) to archetype:jar | ||
MWAR-432 ( | apply reproducible zip (entries order and timestamp) to war:jar | ||
MACR-53 ( | |||
MEAR-280 ( | |||
MEJB-128 ( | |||
MRAR-86 ( | |||
MJLINK-75 ( | apply reproducible zip to the zip file created by the plugin | ||
issues fixed in maven-archiver will have been picked by 9 other plugins managed by Apache Maven team (acr, ear, ejb, jlink, rar), probably other plugins creating zip/jar/tar archives managed outside Apache Maven team will require to do the same | |||
FELIX-6304 ( | order and timestamp of jar entries for bundle goal | ||
FELIX-6404 ( | regression in 5.1.2 | ||
FELIX-6495 ( | bundle:manifest adds Bnd-LastModified even if outputTimestamp is defined | ||
FELIX-6496 ( require bnd #5021( | non-reproducible Export-Package and Private-Package values | ||
FELIX-6602 ( | non-reproducible Include-Resource entry | ||
FELIX-6681 | non-reproducible Export-Service entry | ||
spring-boot-maven-plugin:repackage #20176 ( | timestamp | ||
org.jboss.jandex:jandex-maven-plugin #26 ( | unsorted files (notice: not sure that sorting files at plugin level is sufficient: it seems Jandex indexer itself produces non-reproducible output) | ||
org.jboss.jandex:jandex-maven-plugin #35 replaced by io.smallrye:jandex-maven-plugin #286 ( | jandex.idx output is not stable/reproducible | ||
MJAR-275 ( | outputTimestamp not applied to module-info.class | ||
moditect-maven-plugin:add-module-info #185 ( | creates module-info.class with non-reproducible timestamp | ||
moditect #222 | timestamp is dependant on timezone | ||
SM-5021 ServiceMix depends-maven-plugin:generate-depends-file ( | timestamp in generated depends.txt | ||
XBEAN-335 Geronimo maven-xbean-plugin | timestamp in generated /META-INF/spring-* (Properties format) | ||
KARAF-7367 karaf-maven-plugin:kar #1492 ( | does not take outputTimestamp into account | ||
quarkus-extension-maven-plugin #38364 | timestamp in generated properties META-INF/quarkus-extension.properties, META-INF/quarkus-javadoc.properties and sources *.jdp | ||
tracking of plugins with issues and fixes is now also done in artifact:check-buildplan | issues fixed in maven-archiver will have to be picked by 9 other plugins managed by Apache Maven team (acr, ear, ejb, jlink, rar, war) and perhaps other plugins managed outside Apache Maven team
Debian approach
Debian has a strong reproducible builds structure working on the topic for a few years: see BuildinfoFiles for environment info recording.
...