Sonatype Nexus Artifact Repository Releaser Starter Maven Project
It’s a minimal a reference example for setting up your project to deploy to Maven Central with staging release to Nexus Sonatype repository https://oss.sonatype.org/
This project is based on these instructions from: https://github.com/davidcarboni/releaser
There are two files of interest in this project:
pom.xml - a POM file that meets Maven Central requirements and defines a deployment configurationsettings.xml - a Maven user settings file that defines release deployment configurationThese are set up initially to test with a local Nexus instance, but also contain the Sonatype OSS repository information, commented out.
You’ll also need to follow the instructions for setting up a Sonatype Jira account and creating a ticket here: http://central.sonatype.org/pages/ossrh-guide.html#create-a-ticket-with-sonatype
Here’s a terse summary of the GPG commands you’ll need to generate and publish a key for signing your artifacts. For the full version, see https://docs.sonatype.org/display/Repository/How+To+Generate+PGP+Signatures+With+Maven
# is GPG installed?gpg --version# Generate a key. If in doubt, accept defaluts. I'd recommend a 3072-bit key:gpg --gen-key# Check what was generated:gpg --list-keysgpg --list-secret-keys# You should see:# pub nnnnA/FFFFFFFF YY-MM-DD# ... etc ...# make a note of FFFFFFFF - this is your key ID# Check for sub keys:gpg --edit-key FFFFFFFF# If any "sub" key says "usage: S", refer to the URL above for instructions on deleting it.# Publish key:gpg --keyserver hkp://pool.sks-keyservers.net --send-keys FFFFFFFF
Try running with a local Nexus instance to get the hang of it:
docker run -d -p 8081:8081 --name nexus sonatype/nexus:osscurl http://localhost:8081/nexus/service/local/statusdocker logs nexussettings.xml in the root of this project.The summary is:
git tag -d 0.0.1git push origin :refs/tags/0.0.1
Run mvn clean deploy to build and deploy your project in local Maven repository
The standard Maven plugin used by a Release Process is the maven-release-plugin – the configuration for this plugin is minimal:
<plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-release-plugin</artifactId><version>2.4.2</version><configuration><tagNameFormat>@{project.version}</tagNameFormat><autoVersionSubmodules>true</autoVersionSubmodules><releaseProfiles>releases</releaseProfiles></configuration></plugin>
What is important here is that the releaseProfiles configuration will actually force a Maven profile – the releases profile – to become active during the Release process.
It is in this process that the nexus-staging-maven-plugin is used to perform a deploy to the localhost-nexus-staging Nexus repository:
<profiles><profile><id>releases</id><build><plugins><plugin><groupId>org.sonatype.plugins</groupId><artifactId>nexus-staging-maven-plugin</artifactId><version>1.6.7</version><executions><execution><id>default-deploy</id><phase>deploy</phase><goals><goal>deploy</goal></goals></execution></executions><configuration><serverId>localhost-nexus-staging</serverId><nexusUrl>http://localhost:8081/nexus/</nexusUrl><skipStaging>true</skipStaging></configuration></plugin></plugins></build></profile></profiles>
The plugin is initially configured to perform the Release process without the staging mechanism (skipStaging=true).
If you perform release to a local Nexus OSS repository, you will need to skip staging with <skipStaging>true</skipStaging> tag in nexus-staging-maven-plugin <configuration>. Otherwise, you will get an error Nexus instance does not support staging workflow v2, i.e.:
<configuration><serverId>localhost-nexus-staging</serverId><nexusUrl>http://localhost:8081/nexus</nexusUrl><skipStaging>true</skipStaging></configuration>
For public Nexus releases, use the following configuration in nexus-staging-maven-plugin:
<configuration><serverId>sonatype-nexus-staging</serverId><nexusUrl>https://oss.sonatype.org/</nexusUrl><autoReleaseAfterClose>false</autoReleaseAfterClose></configuration>
Let’s break apart the release process into small and focused steps. We are performing a Release when the current version of the project is a SNAPSHOT version – say 0.0.1-SNAPSHOT.
Ensure your artifact version is a -SNAPSHOT, then run the following:
mvn release:cleanCleaning a Release will:
delete the release descriptor (release.properties)
delete any backup POM files
mvn release:prepareNext part of the Release process is Preparing the Release; this will:
perform some checks – there should be no uncommitted changes and the project should depend on no SNAPSHOT dependencies
change the version of the project in the pom file to a full release number (remove SNAPSHOT suffix) – in our example – 0.0.1
run the project test suites
commit and push the changes
create the tag out of this non-SNAPSHOT versioned code
increase the version of the project in the pom – in our example – 0.0.2-SNAPSHOT
commit and push the changes
mvn release:performThe last part of the Release process is Performing the Release; this will:
checkout release tag from SCM
build and deploy released code
auto-sign artifacts with your gpg.passphrase from settings.xml
This step of the process relies on the output of the Prepare step – the release.properties.
For more options, including rolling back a release or cleaning up a failed release, see: http://maven.apache.org/maven-release/maven-release-plugin/
If you find that the release is deploying a SNAPSHOT version instead of the release artifact, it may be because the release process has changed since I first uploaded this project to Github. I’ve updated these instructions to match, so just check your release plugin configuration matches the example in this project.
Once you’re set up with Sonatype, have deployed your artifacts and commented on your Jira ticket, you’ll need to follow these instructions in order to complete the process:
http://central.sonatype.org/pages/ossrh-guide.html
Here are the specific Maven instructions, including the nexus-staging-maven-plugin setup:
http://central.sonatype.org/pages/apache-maven.html
David Carboni https://github.com/davidcarboni/releaser