Nexus is your "own" repository that you can manage. It play a role of "proxy" allowing you to collect and manage your dependencies and artifacts and keep them inside the organisation.

This tutorial will focus on configuring Nexus with Maven.

The easiest way is to run a docker

docker run -d -p 8081:8081 --name nexus sonatype/nexus3

or install it on cloud or on-promises server: please check the following link for more info https://help.sonatype.com/repomanager3/installation

To configure maven to use Nexus, you need the following URLs:

1. Maven hosted group URL
2. Maven hosted snapshots URL
3. Maven hosted release URL

You can find these URLs in different places based on Nexus version

Click "copy" to get the URL

The configuration is divided into two part:

1. configure your maven (local setting)
2. configure project setting (pom.xml)

first you have to configure maven setting to point to Nexus server. This is done by adding settings.xml file in your home path for maven ( maven will create a folder called .m2 in your home folder. for Linux it will be located in ~/.m2 and for windows C:\Users\USERNAME.m2 will use it as local cache of the artifacts that you already downloaded

Create new file in ${user.home}/.m2/settings.xml

<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.1.0"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.1.0 http://maven.apache.org/xsd/settings-1.1.0.xsd">

	<!-- default username and password when you run Nexus in docker -->
	<servers>
		<server>
			<id>nexus-snapshots</id>
			<username>admin</username>
			<password>admin123</password>
		</server>
		<server>
			<id>nexus-releases</id>
			<username>admin</username>
			<password>admin123</password>
		</server>
	</servers>

	<profiles>
		<profile>
			<id>nexus-local</id>
			<activation>
				<activeByDefault>false</activeByDefault>
			</activation>
			<properties>
				<mirror_cental_id>central</mirror_cental_id>
				<mirror_cental_url>http://YOUR_SERVER:8081/repository/maven-public/</mirror_cental_url>
				<nexus_spanshot_url>http://YOUR_SERVER:8081/repository/maven-snapshots/</nexus_spanshot_url>
				<nexus_release_url>http://YOUR_SERVER:8081/repository/maven-snapshots/</nexus_release_url>
			</properties>
		</profile>
	</profiles>

	<activeProfiles>
		<activeProfile>nexus-local</activeProfile>
	</activeProfiles>
	<mirrors>
		<mirror>
			<id>central</id>
			<name>central</name>
			<url>http://YOUR_SERVER:8081/repository/maven-public/</url>
			<mirrorOf>*</mirrorOf>
		</mirror>
	</mirrors>
</settings>

Using the profiles, you can easily change your project deployment to another server

Here there are two options:

In pom.xml add the flowing lines: This section is not needed since we already configure it is settings.xml in section 'mirrors'

  <repositories>
    <repository>
      <id>maven-group</id>
      <url>http://YOUR_SERVER:8081/repository/maven-group/</url>
    </repository>
  </repositories>

and then you can use

   $ mvn install 

  <distributionManagement>
    <snapshotRepository>
      <id>nexus-snapshots</id>
      <url>${nexus_spanshot_url}</url>
    </snapshotRepository>
    <repository>
      <id>nexus-releases</id>
     <url>${nexus_release_url}</url>
    </repository>
  </distributionManagement>

Maven will get the variable values from Settings.xml. To deploy use

$ mvn deploy

Of course it is not a good idea to write down your password in plain text, especially if this password is for LDAP or Active Directory account.

Maven provide a solution to encrypt your password. You have to add additional settings-security.xml in ${user.home}/.m2

For more info check https://stackoverflow.com/questions/30769636/how-does-maven-3-password-encryption-work

1. Create master password for encrypting/decryption

   $ mvn --encrypt-master-password <password>
   

   the output will be something like

   {V1E44GUTUFYHLqoCa+rf/qxdg06PFX2yTgnJlTxjvCA=}
   

2. add the following lines to file settings-security.xml

   <settingsSecurity>
   	<master>{jSMOWnoPFgsHVpMvz5VrIt5kRbzGpI8u+9EF1iFQyJQ=}</master>
   </settingsSecurity>
   

• Create server password

  $ mvn --encrypt-password <password>
  

  the output will be something like

  {8Xm7QdJv8WMHfwU4B4KawjEB9TzK74CXg9Q/Ii8DkQE=}
  

• replace your plain password in settings.xml with encrypted password

  <server>
  	<id>nexus-releases</id>
  	<username>admin</username>
  	<password>{8Xm7QdJv8WMHfwU4B4KawjEB9TzK74CXg9Q/Ii8DkQE=}</password>
  </server>
  

• Server id in settings.xml and pon.xml should match. For example if the server id for snapshots in settings.xml is "nexus-snapshots" and in pom.xml is "nexus-snapshot" (missing one letter 's') you will get error:

  
  Failed to deploy artifacts: Could not transfer artifact  ...... eturn code is: 401, ReasonPhrase: Unauthorized.
  

• If you change your master encrypted password, you should encrypt the server password again
• If you try to encrypt server password without creating settings-security.xml you will get error :

   java.io.FileNotFoundException: ${user.home}/.m2/settings-security.xml (The system cannot find the file specified)
  

• You need "deploy" permissions to deploy your artifacts to Nexus if you are not the admin

Shiyar Daoud

enjoy and happy coding