By

Craig Motlin

●

In 

all, 

maven

●

Published 2024-05-13

There are a number of best practices that can be handled at once by inheriting from a parent pom that takes care of them all. The following sections cover resource encodings and reproducible builds. As an alterantive, declare a parent pom on liftwizard-minimal-parent which handles all of these.

<parent>
    <groupId>io.liftwizard</groupId>
    <artifactId>liftwizard-minimal-parent</artifactId>
    <version>${liftwizard.version}</version>
</parent>

If you don't specify a resource encoding, you may encounter a warning from maven-resources-plugin like: [WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!

You can fix it by specifying a character encoding scheme.

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>

This will become unnecessary starting with Maven 4.x.

A build is reproducible if given the same source code, build environment and build instructions, any party can recreate bit-by-bit identical copies of all specified artifacts.

You can enable Reproducible Builds mode for plugins by specifying the following property.

<properties>
    <project.build.outputTimestamp>2000-01-01T00:00:00Z</project.build.outputTimestamp>
</properties>

You will need to run mvn artifact:check-buildplan and mvn verify artifact:compare as described in the guide to ensure builds are reproducible.

You can specify the default goal to run when you run mvn without any arguments.

<defaultGoal>verify</defaultGoal>

verify is a better choice than install in the presence of concurrent builds that may write to .m2/repository simultaneously.

verify is a better choice than clean verify because clean is a destructive operation, users may not expect it to be run by default, and it's easy to run mvn clean when you need it.

Maven builds are configured by binding plugins to maven's lifecycle phases.

Maven binds some plugins to the “main” phases, even if you don’t declare any plugins in your pom.xml.

The versions of the default plugins changes between maven versions, and even the list of plugins grows over time. Maven 3.9.6 binds:

We can support reproducible builds even with different versions of maven as long as all the plugin versions are the same. To enable plugin consistency across a team, we specify versions of the plugins in the parent pom.