How to publish artifacts to Maven Central via Gradle

signing.keyId=KEY_ID
signing.password=KEY_PASSWORD
signing.secretKeyRingFile=/PATH/TO/SECRET/RING/FILE


Tips

• Add the gradle.properties to your project root folder rather than in the .gradle  or gradle folders. Why? I am using Intellij IDEA and my IDEA gradle settings file could not be found if I put it either of those two folders. I had to put it in the project root.
• ADD THE gradle.properties FILE TO YOUR PROJECT’S .gitignore. You never want to release this to the repo (it has your key password).

Below is the full code listing of the build.gradle ​com.bmuschko.nexus plugin. Add it to your current gradle code:

buildscript {
  repositories {
     jcenter()
  }
  dependencies {
     classpath 'com.bmuschko:gradle-nexus-plugin:2.3.1'
  }
}

apply plugin: 'com.bmuschko.nexus'

archivesBaseName = 'teachUpload-jvm'
group = "com.yourCompany.package"
version = "0.1"

modifyPom {
 project {
   name 'teachUpload'
   description 'Teaching how to use gradle.'
   url 'https://bitbucket.org/objdict/objjson'
   inceptionYear '2018'

   scm {
     url 'https://bitbucket.org/objdict/objjson'
     connection 'scm:https://bitbucket.org/objdict/objjson.git'
     developerConnection 'scm:git://bitbucket.org/objdict/objjson.git'
   }

   licenses {
     license {
       name 'The Apache Software License, Version 2.0'
       url 'http://www.apache.org/licenses/LICENSE-2.0.txt'
       distribution 'repo'
     }
   }

   developers {
     developer {
       id 'albertgao'
       name 'Albert Gao'
       email 'albert.gao@salect.co.nz'
     }
   }
 }
}

extraArchive {
 sources = true
 tests = true
 javadoc = true
}

nexus {
 sign = true
 repositoryUrl = 'https://oss.sonatype.org/service/local/staging/deploy/maven2/'
 snapshotRepositoryUrl = 'https://oss.sonatype.org/content/repositories/snapshots/'
}

Tips

• You don’t need to create the sourceJar in the build.gradle settings file above. The ​com.bmuschko.nexus plugin will add it for you.

Double click it to execute the uploadArchives task.

You might see the following error when you first upload:
Could not find metadata com.yourCompany.package:teachUpload-jvm/maven-metadata.xml in remote (https://oss.sonatype.org/service/local/staging/deploy/maven2/)

• This is not an error, just information – this is your first time, so no meta file previously existed on the server.
• Your package will have already been uploaded if this is the only information displayed.

Congratulations! After completing all of these steps, your package should finally have been uploaded onto Sonatype OSS Nexus.

Just add the following gradle code:

plugins {
    id 'io.codearte.nexus-staging' version '0.11.0'
}
nexusStaging {
    // optional if packageGroup == project.getGroup()
    packageGroup = "org.mycompany" 

    // when not defined will be got from server using "packageGroup"
    stagingProfileId = "yourStagingProfileId"
}

Now several gradle tasks will exist:

• closeRepository – closes an open repository with the uploaded artifacts. There should be just one open repository available in the staging profile (possible old/broken repositories can be dropped with Nexus GUI)
• releaseRepository – releases a closed repository (required to put artifacts to Maven Central aka The Central Repository)
• closeAndReleaseRepository – closes and releases a repository (an equivalent to closeRepository and then releaseRepository)
• getStagingProfile – gets and displays a staging profile id for a given package group. This is a diagnostic task to get the value and put it into the configuration closure as stagingProfileId.

Now you should already have uploaded your artifacts to the Nexus repo. All you need to do now is to run the closeAndReleaseRepository, and your artifacts will be added to Maven Central (within 10 min ~ 2 hours).

Tips:

• If you have a multiple project gradle setup. You just need to add this plugin at the root level.

7.2 Manually publish via Nexus website

The reason we still need this publishing option is that sometimes there are some errors during the auto-publishing phase. After publishing, check the status on the website. Follow the steps below to publish manually if the auto option is unsuccessful.

1. Open the Nexus Repository Manager.
2. Click the Log In button in the upper right corner of the screen.
3. On the right-hand side, click Staging Repositories.
4. Search your project by following this search pattern: if for example, your groupId is com.google, then enter comgoogle.
5. Select the correct item and click the Close button to close it – this action finalizes the upload.
6. Click the Refresh button to get the latest updates (remember this trick, no ajax yet).
7. If see any errors:
   • You can inspect them at the Activity panel.
   • You will need to:
     •  Drop this upload
     • Find and fix the errors in your local folder
     • Run the uploadArchives task again
     • Then finalize the upload by pressing the Close button again and then continue
8. If you see NO errors:
   • Click the Release button to publish

Congratulations! Your artifact should have finally been uploaded to Maven Central.

repositories {
    mavenCentral()
}

dependencies {
    compile "com.yourCompany.package:teachUpload-jvm:0.1"
}

The pattern in our example is: groupId:archiveBaseName:versionNumber
where:

          groupId = com.yourCompany.package
          archiveBaseName = teachUpload-jvm
          versionNumber = 0.1