Code samples for Building minimal Docker Containers for Java Applications on blog.realkinetic.com

fat-build.gradle

plugins {
  id "java"
}

repositories {
  mavenCentral()
}

dependencies {
  compile "joda-time:joda-time:2.10.1"
  testCompile "junit:junit:4.12"
}

compileJava {
  sourceCompatibility = 1.7
  targetCompatibility = 1.7
}

jar {
  baseName = "hello-world"
  manifest {
    attributes(
      "Main-Class": "hello.HelloWorld"
    )
  }
  from {
    configurations.compile.collect { it.isDirectory() ? it : zipTree(it) }
  }
}

fat-pom.xml

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.realkinetic</groupId>
  <artifactId>hello-world</artifactId>
  <version>1.0.0</version>
  <name>Hello World</name>
  <packaging>jar</packaging>

  <properties>
    <maven.compiler.source>1.7</maven.compiler.source>
    <maven.compiler.target>1.7</maven.compiler.target>
  </properties>

  <repositories>
    <repository>
      <id>central</id>
      <name>Maven Repository Switchboard</name>
      <layout>default</layout>
      <url>http://repo1.maven.org/maven2</url>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
    </repository>
  </repositories>

  <pluginRepositories>
    <pluginRepository>
      <id>central</id>
      <name>Maven Plugin Repository</name>
      <url>http://repo1.maven.org/maven2</url>
      <layout>default</layout>
      <snapshots>
        <enabled>false</enabled>
      </snapshots>
      <releases>
        <updatePolicy>never</updatePolicy>
      </releases>
    </pluginRepository>
  </pluginRepositories>

  <dependencies>
    <dependency>
      <groupId>joda-time</groupId>
      <artifactId>joda-time</artifactId>
      <version>2.10.1</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <executions>
          <execution>
            <goals>
              <goal>shade</goal>
            </goals>
            <configuration>
              <shadedArtifactAttached>true</shadedArtifactAttached>
              <transformers>
                <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
                  <mainClass>hello.HelloWorld</mainClass>
                </transformer>
              </transformers>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

HelloWorld.java

package hello;

import org.joda.time.LocalTime;

public class HelloWorld {
  public static void main(String[] args) {
    LocalTime currentTime = new LocalTime();
    System.out.println("The current local time is: " + currentTime);
    System.out.println("Hello World");
  }
}