How to access maven.build.timestamp for resource f

Question

I am using maven 3.0.4 and would like to make the build timestamp accessible to my application. For this, I'm putting a placeholder in a .properties file and let maven filter on build. While this is working fine for ${project.version}, ${maven.build.timestamp} is not substituted on filtering.

The property seems to be available on build - I can use it to modify the artifact name:

<finalName>${project.artifactId}-${maven.build.timestamp}</finalName>

So why is it not available for resource filtering? And, more importantly, how do I make it accessible?

Answer 1

I have discovered this article, explaining that due to a bug in maven, the build timestamp does not get propagated to the filtering. The workaround is to wrap the timestamp in another property:

<properties>
   <timestamp>${maven.build.timestamp}</timestamp>
   <maven.build.timestamp.format>yyyy-MM-dd HH:mm</maven.build.timestamp.format>
</properties>

Filtering then works as expected for

buildTimestamp=${timestamp}

Answer 2

Adding Maven properties at the pom project level does't take into account correct local Timezone, so timestamp may appear wrong :

<properties><timestamp>${maven.build.timestamp}</timestamp></properties>

Using the build-helper-maven-plugin applies the correct timezone and current daylight saving to the timestamp :

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>build-helper-maven-plugin</artifactId>
            <version>1.9.1</version>
            <executions>
                <execution>
                    <id>timestamp-property</id>
                    <goals>
                        <goal>timestamp-property</goal>
                    </goals>
                    <configuration>
                        <name>timestamp</name>
                        <pattern>yyyy-MM-dd HH:mm:ss</pattern>
                        <timeZone>Europe/Zurich</timeZone>
                    </configuration>
                </execution>
            </executions>
        </plugin>
     </plugins>
     <resources>
         <resource>
             <directory>src/main/resources</directory>
             <filtering>true</filtering>
         </resource>
     </resources>
 </build>

When packaging, Maven will replace any token timestamp in /resources folder, e.g. resources/version.properties :

build.timestamp=${timestamp}

You can then load this properties file in your Application.

Answer 3

I can confirm as of Maven 3.x {maven.build.timestamp} is "working" now. They work arounded the problem, apparently. No additional properties workaround needed anymore.

However, be careful your "filtering" plugin (maven-resources-plugin) is up to date. It needs to be relatively new, so if mvn help:effective-pom shows an old version (ex: 2.6), bump it to something newer, fixed it for me, 3.x ex:

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-resources-plugin</artifactId>
  <version>3.1.0</version>
</plugin>

<properties><timestamp>... workaround is no longer required...

This also cleared up, kind of, why it was working in IntelliJ but not the command line. IntelliJ probably uses their own "modified/internal" maven constants, so it was working there, but not from maven command line.

Also note if you add a filtering resource directory to you pom, you may need to also "re-add" the default directory, it gets lost, ex:

  <resource>
    <directory>src/main/resources-filtered</directory> <!-- to get "maven.build.timestamp" into resource properties file -->
    <filtering>true</filtering>
  </resource>
  <resource>
    <directory>src/main/resources</directory> <!-- apparently have to add this is you have the other... -->
  </resource>

NB if you're using spring boot as your parent, you have to use @maven.build.timestamp@ instead. Also note if you're using spring boot there's a file META-INF/build-info.properties that is optionally created by the spring-boot-maven-plugin that you can read (spring provides a BuildProperties bean for convenience reading it).

Answer 4

In order to enrich the Stackoverflow content for others, that like me, found this post as a way to solve the "problem" of ${maven.build.timestamp}. This is not a maven bug, but an expected behavior of m2e, as can be seen in this post.

Therefore, I believe that we can not expect the solution to be "corrected", since, from what I understand, the correction involves conceptual issues.

In my case, what I did was use the plugin (buildnumber-maven-plugin) as described in this other post.