JarCastingNexus Releaser
Summary
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
Using Nexus 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 configuration
These 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
GPG key generation
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-keys
gpg --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
Test with a local Nexus instance
Try running with a local Nexus instance to get the hang of it:
- Map docker machine host port 8081 to guest container port 8081 in VirtualBox machine instance network settings.
- Run Nexus Docker image with binding the exposed port 8081 to the host:
docker run -d -p 8081:8081 --name nexus sonatype/nexus:oss - Test Nexus instance is running:
curl http://localhost:8081/nexus/service/local/status - Check instance logs with
docker logs nexus - open http://localhost:8081/nexus
- the default Nexus deployment username and password are already set in the example Maven
settings.xmlin the root of this project. - if you do practice releases, note that the tags created by the release plugin will get pushed to your remote so you'll need to delete them after practice runs. Deleting remote tags isn't obvious so here's a post that explains how: http://nathanhoad.net/how-to-delete-a-remote-git-tag.
The summary is:
git tag -d 0.0.1
git push origin :refs/tags/0.0.1
Deploy artifact locally
Run mvn clean deploy to build and deploy your project in local Maven repository
Maven Nexus release POM configuration
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>
Maven release process to Nexus repository
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:clean
Cleaning a Release will:
delete the release descriptor (release.properties) delete any backup POM files
mvn release:prepare
Next 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:perform
The 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.
Next steps
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
Credits
David Carboni https://github.com/davidcarboni/releaser
