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Deploy Java artifacts to the CASTOR namespace in Maven Central

Maven Central is the de-facto repository for hosting software artifacts that compile to the JVM. Here we describe the process of releasing a new artifact in Maven Central following an step-by-step approach.

Table of content

1. Create a JIRA ticket in Sonatype

First, you need to create a JIRA account and submit a ticket there requesting adding your project artifact coordinates (groupId:artifactId:version) to the namespace se.kth.castor in Sonatype:

  1. Create a JIRA account
  2. Create a New Project ticket

A staging repository is already configured for the requested artifact’s coordinates. You need to find someone with a deployer role in CASTOR that comment on the ticket to verify your request (e.g., you can contact cesarsotovalero). Below is an example of a ticket that I created for the artifacts: depclean-core and depclean-maven-plugin.

The ticked review is a manual process, it normally takes less than 2 business days to be answered.

2. Configuring the POM

After the approval of the ticket, you need to provide additional information to the POM of the Maven project (or module) to be deployed. To do so, follow each of the steps below exactly as they are. Below is an example for the already released artifact se.kth.castor:depclean-maven-plugin:1.0.0

  1. Choose appropriate coordinates as explained here:

     <groupId>se.kth.castor</groupId>
 <artifactId>depclean-maven-plugin</artifactId>
 <version>1.0.0</version>

  2. Add your project name, description, and URL:

    <name>depclean-maven-plugin</name>
<description>DepClean is a plugin for automatically remove unused dependencies in Maven projects</description>
<url>https://github.com/castor-software/depclean</url>

  3. Add licence information:

     <licenses>
    <license>
       <name>MIT License</name>
       <url>http://www.opensource.org/licenses/mit-license.php</url>
       <distribution>repo</distribution>
    </license>
 </licenses>

  4. Add information about developer/s :

      <developers>
      <developer>
         <id>cesarsotovalero</id>
         <name>César Soto Valero</name>
         <email>cesarsotovalero@gmail.com</email>
         <organization>Castor Software Research Centre</organization>
         <organizationUrl>https://www.castor.kth.se/</organizationUrl>
      </developer>
  </developers>

  5. Add SCM information, the following example uses GitHub:

     <scm>
    <url>https://github.com/castor-software/depclean/</url>
    <connection>scm:git:git:github.com/castor-software/depclean.git</connection>
    <developerConnection>scm:git:git@github.com:castor-software/depclean.git</developerConnection>
 </scm>

  6. Add distribution management and authentication to Sonatype via the nexus-staging-maven-plugin:

     <distributionManagement>
   <snapshotRepository>
     <id>ossrh</id>
     <url>https://oss.sonatype.org/content/repositories/snapshots</url>
   </snapshotRepository>
 </distributionManagement>
 <build>
   <plugins>
     <plugin>
       <groupId>org.sonatype.plugins</groupId>
       <artifactId>nexus-staging-maven-plugin</artifactId>
       <version>1.6.7</version>
       <extensions>true</extensions>
       <configuration>
         <serverId>ossrh</serverId>
         <nexusUrl>https://oss.sonatype.org/</nexusUrl>
         <autoReleaseAfterClose>true</autoReleaseAfterClose>
       </configuration>
     </plugin>
     ...
   </plugins>
 </build>

  7. Add javadoc and sources attachments using the maven-javadoc-plugin and maven-source-plugin :

    <build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-source-plugin</artifactId>
      <version>2.2.1</version>
      <executions>
        <execution>
          <id>attach-sources</id>
          <goals>
            <goal>jar-no-fork</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-javadoc-plugin</artifactId>
      <version>2.9.1</version>
      <executions>
        <execution>
          <id>attach-javadocs</id>
          <goals>
            <goal>jar</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

  8. Add GPG signed components using the maven-gpg-plugin:

    <build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-gpg-plugin</artifactId>
      <version>1.5</version>
      <executions>
        <execution>
          <id>sign-artifacts</id>
          <phase>verify</phase>
          <goals>
            <goal>sign</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

  9. Follow this instructions to encrypt your artifact with gpg2 and distribute your public key to a key server (e.g., http://keys.gnupg.net). Do not forget to choose a passphrase to protect your secret key. Then add your gpg credentials with your passphrase to your Mavensettings.xml file locally:

     <settings>
   <profiles>
     <profile>
       <id>ossrh</id>
       <activation>
         <activeByDefault>true</activeByDefault>
       </activation>
       <properties>
         <gpg.executable>gpg2</gpg.executable>
         <gpg.passphrase>the_pass_phrase</gpg.passphrase>
       </properties>
     </profile>
   </profiles>
 </settings>

  10. Add nexus-staging-maven-plugin with the following configurations:

    <build>
<plugins>
  <plugin>
    <groupId>org.sonatype.plugins</groupId>
    <artifactId>nexus-staging-maven-plugin</artifactId>
    <version>1.6.7</version>
    <extensions>true</extensions>
    <configuration>
       <serverId>ossrh</serverId>
       <nexusUrl>https://oss.sonatype.org/</nexusUrl>
       <autoReleaseAfterClose>true</autoReleaseAfterClose>
    </configuration>
  </plugin>
</plugins>

3. Release to Maven Central

Finally, run a deployment to OSSRH and an automated release to the Central Repository with the following command:

  mvn clean deploy

After this, the Central sync will be activated for your artifact. After you successfully deploy, your artifact will be published to Maven Central, typically within 10 minutes, though updates to search.maven.org can take up to two hours.

References