buildinfo-maven-example

This document and example code repository describes how to render a properties file containing build timestamp and more information using maven.

Howto

Template file

The buildinfo.properties file template is placed in the resources directory and can contain any Maven property.

Example src/main/resources/buildinfo.properties:

version=${project.version}
date=${maven.build.timestamp}

Filtering

Use maven-resources-plugin to filter the file and replace it with interpolated variables.

Example pom.xml:

<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-resources-plugin</artifactId>
            <version>${maven-resources-plugin.version}</version>
        </plugin>

        ...

    <plugins>

    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>true</filtering>
            <includes>
                <include>**/buildinfo.properties</include>
            </includes>
        </resource>
        <resource>
            <directory>src/main/resources</directory>
            <filtering>false</filtering>
            <excludes>
                <exclude>**/buildinfo.properties</exclude>
            </excludes>
        </resource>
    </resources>
<build>

The filtered file will be included in the compile result, instead of the template:

target/classes/buildinfo.properties:

version=0.0.1-SNAPSHOT
date=2020-09-04T08:11:02Z

NOTE: if maven.build.timestamp is not replaced with a timestamp, your maven-resources-plugin version might be outdated.

From there (either at runtime if packaged into a jar, or at test stage) it can be read like any resource. See example code below or in this repository's Main.java.

Packaging (optional)

The above will provide build information inside the packaged jar, primarily to be read by the application at runtime.

To have build information readily available in your distribution tarball (for example to inspect it via cat buildinfo.properties on the server), include it via src/assembly/distribution.xml:

<?xml version="1.0" encoding="UTF-8"?>
<assembly
    xmlns="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/plugins/maven-assembly-plugin/assembly/1.1.2 http://maven.apache.org/xsd/assembly-1.1.2.xsd">
    <id>distribution</id>
    <formats>
        <format>tar.gz</format>
    </formats>
    <includeBaseDirectory>false</includeBaseDirectory>
    <files>
        <file>
            <source>${project.build.directory}/classes/buildinfo.properties</source>
            <outputDirectory>.</outputDirectory>
        </file>
    </files>

    ...

</assembly>

This definition will store the buildinfo.properties file at toplevel in the distributable tarball.

Results

After these steps, the buildinfo.properties file can be found at the following locations:

target/classes/buildinfo.properties
buildinfo-maven-example-0.0.1-SNAPSHOT.jar/buildinfo.properties
buildinfo-maven-example-0.0.1-SNAPSHOT-distribution.tar.gz/buildinfo.properties

Accessing the properties at runtime

The file can be loaded like any resource, see example code in Main.java:

    Properties buildInfo = new Properties();

    try (InputStream inputStream = Main.class.getResourceAsStream("/buildinfo.properties")) {
        buildInfo.load(inputStream);
    }

    System.out.println("build date: " + buildInfo.getProperty("date"));
    System.out.println("build version: " + buildInfo.getProperty("version"));

Relevant dependencies:

maven-resources-plugin for interpolation
maven-assembly-plugin for creating a tarball containing the jar and the properties file

Example code

This repository contains a fully functional example demonstrating rendering of a buildinfo file via maven.

Build instructions

mvn clean package

=> will render the buildinfo.properties file

Run instructions

java -jar target/buildinfo-maven-example-0.0.1-SNAPSHOT.jar

=> will output properties from buildinfo.properties

codegourmet / buildinfo-maven-example