{inall}
Historically {pro} and {oss} started as a repository manager supporting the Maven repository format. While it supports many other repository formats now, the Maven repository format is still the most common and well supported format for build and provisioning tools running on the JVM and beyond.
This chapter shows example configurations for using the repository manager with Apache Maven and a number of other tools. The setups take advantage of merging many repositories and exposing them via a repository group. Setting this up is documented in the chapter in addition to the configuration used by specific tools.
To use {pro} and {oss} with Apache Maven, we configure Maven to check the repository manager instead of the default, built-in connection to the Central Repository.
To do this, you add a mirror configuration and override the default configuration for the central repository in your ~/.m2/settings.xml as shown in Configuring Maven to Use a Single Repository Group.
<settings>
<mirrors>
<mirror>
<!--This sends everything else to /public -->
<id>nexus</id>
<mirrorOf>*</mirrorOf>
<url>http://localhost:8081/nexus/content/groups/public</url>
</mirror>
</mirrors>
<profiles>
<profile>
<id>nexus</id>
<!--Enable snapshots for the built in central repo to direct -->
<!--all requests to nexus via the mirror -->
<repositories>
<repository>
<id>central</id>
<url>http://central</url>
<releases><enabled>true</enabled></releases>
<snapshots><enabled>true</enabled></snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>central</id>
<url>http://central</url>
<releases><enabled>true</enabled></releases>
<snapshots><enabled>true</enabled></snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
</profiles>
<activeProfiles>
<!--make the profile active all the time -->
<activeProfile>nexus</activeProfile>
</activeProfiles>
</settings>
In Configuring Maven to Use a Single Repository Group, we have defined a single profile called nexus. It configures a repository and a pluginRepository with the id central that overrides the same repositories in the super pom. The super pom is internal to every Apache Maven install and establishes default values. These overrides are important since they change the repositories by enabling snapshots and replacing the URL with a bogus URL. This URL is overridden by the mirror setting in the same settings.xml file to point to the URL of your single repository group. This group can, therefore, contain release as well as snapshot components and Maven will pick them up.
The mirrorOf pattern of * causes any repository request to be redirected to this mirror and to your single repository group, which in the example is the public group.
It is possible to use other patterns in the mirrorOf field. A possible valuable setting is to use external:*. This matches all repositories except those using localhost or file based repositories. This is used in conjunction with a repository manager when you want to exclude redirecting repositories that are defined for integration testing. The integration test runs for Apache Maven itself require this setting.
More documentation about mirror settings can be found in the mini guide on the Maven web site.
As a last configuration the nexus profile is listed as an active profile in the activeProfiles element.
If you’ve configured your Maven settings.xml or other build tool configuration to use the public repository group as a mirror for all repositories, you might encounter projects that are unable to retrieve components from your local repository manager installation.
This usually happens because you are trying to build a project that has defined a custom set of repositories and snapshot repositories or relies on the content of other publically available repositories in its configuration. When you encounter such a project all you have to do is
-
add this repository to your repository manager as a new proxy repository
-
and then add the new proxy repository to the public group.
The advantage of this approach is that no configuration change on the build tool side is necessary at all.
To add a repository, log in as an administrator, and click on the 'Repositories' link in the left-hand navigation menu in the 'Views/Repositories' section as displayed in Creating a New Proxy Repository.
Clicking on this link should bring up a window that lists all the configured repositories. You’ll then want to create a new proxy repository. To do this, click on the 'Add' link that is directly above the list of repositories. When you click the 'Add' button, click the down arrow directly to the right of the word 'Add', this will show a drop-down which has the options: 'Hosted Repository', 'Proxy Repository', 'Virtual Repository', and 'Repository Group'. Since you are creating a proxy repository, click on 'Proxy Repository'.
Once you do this, you will see a screen resembling Configuring a Proxy Repository. Populate the required fields 'Repository ID' and the 'Repository Name'. The 'Repository ID' will be part of the URL used to access the repository, so it is recommended to avoid characters that could cause problems there or on the filesystem storage. It is best to stick with lowercase alphanumerics. Set the 'Repository Policy' to 'Release', and the 'Remote Storage Location' to the public URL of the repository you want to proxy.
Once you’ve filled out this screen, click on the 'Save' button. The repository manager is now configured to proxy the repository. If the remote repository contains snapshots as well as release components, you will need to repeat the process creating a second proxy repository and setting the policy to 'Snapshots'.
Next you will need to add the new repositories to the 'Public Repositories' repository group. To do this, click on the 'Repositories' link in the left-hand main menu in the 'Views/Repositories' section. The repository manager lists Groups and Repositories in the same list so click on the public group. After clicking on the 'Public Repositories' group, you should see the 'Browse' and 'Configuration' tabs in the lower half of the user interface.
|
Note
|
If you click on a repository or a group in the 'Repositories' list and you do not see the 'Configuration' tab, this is because your user account does not have administrative privileges. To perform the configuration tasks outlined in this chapter, you will need to be logged in as a user with administrative privileges. |
Clicking on the 'Configuration' tab will bring up a screen which looks like Adding New Repositories to a Repository Group.
To add the new repository to the public group, find the repository in the 'Available Repositories' list on the right, click on the repository you want to add and drag it to the left to the 'Ordered Group Repositories' list. Once the repository is in the 'Ordered Group Repositories' list you can click and drag the repository within that list to alter the order in which a repository will be searched for a matching component.
|
Note
|
The repository manager user interface makes use of the Javascript widget library ExtJS. ExtJS provides for a number of UI widgets that allow for rich interaction like the drag-drop UI for adding repositories to a group and reordering the contents of a group. |
In the last few sections, you learned how to add a new custom repositories to a build in order to download components that are not available in the Central Repository.
If you were not using a repository manager, you would have added these repositories to the repository element of your project’s POM, or you would have asked all of your developers to modify ~/.m2/settings.xml to reference two new repositories. Instead, you used the repository manager to add the two repositories to the public group. If all of the developers are configured to point to the public repository group, you can freely swap in new repositories without asking your developers to change local configuration, and you’ve gained a certain amount of control over which repositories are made available to your development team. In addition the performance of the component resolving across multiple repositories will be handled by repository manager and therefore be much faster than client side resolution done by Maven each time.
Apache Ivy is a dependency manager often used in Apache Ant builds. It supports the Maven repository format and can be configured to download dependencies that can be declared in the ivy.xml file. This configuration can be contained in the ivysettings.xml. A minimal example for resolving dependencies from a repository manager running on localhost is shown in Minimal Apache Ivy Settings.
<ivysettings>
<settings defaultResolver="nexus"/>
<property name="nexus-public"
value="http://localhost:8081/nexus/content/groups/public"/>
<resolvers>
<ibiblio name="nexus" m2compatible="true" root="${nexus-public}"/>
</resolvers>
</ivysettings>
These minimal settings allow the ivy:retrieve task to download the declared dependencies.
To deploy build outputs to a repository with the ivy:publish task, user credentials and the URL of the target repository have to be added to ivysettings.xml and the makepom and publish tasks have to be configured and invoked.
Full example projects can be found in the ant-ivy folder of the documentation examples project. A full build of the simple-project, including downloading the declared dependencies and uploading the build output to the repository manager can be invoked with
cd ant-ivy/simple-project ant deploy
Further details about using these example projects can be found in [eval].
Eclipse Aether is the dependency management component used in Apache Maven 3+. The project provides Ant tasks that can be configured to download dependencies that can be declared in pom.xml file or in the Ant build file directly.
This configuration can be contained in your Ant build.xml or a separate file that is imported. A minimal example for resolving dependencies from a repository manager running on localhost is shown in Minimal Setup for Aether Ant Tasks.
<project xmlns:aether="antlib:org.eclipse.aether.ant" ....>
<taskdef uri="antlib:org.eclipse.aether.ant"
resource="org/eclipse/aether/ant/antlib.xml">
<classpath>
<fileset dir="${aether.basedir}"
includes="aether-ant-tasks-*.jar" />
</classpath>
</taskdef>
<aether:mirror id="mirror"
url="http://localhost:8081/nexus/content/groups/public/"
mirrorOf="*"/>
...
</project>
These minimal settings allow the aether:resolve task to download the declared dependencies.
To deploy build outputs to a repository with the aether:deploy task, user authentication and details about the target repositories have to be added .
Full example projects can be found in the ant-aether folder of the documentation examples project. A full build of the simple-project, including downloading the declared dependencies and uploading the build output to Nexus can be invoked with
cd ant-aether/simple-project ant deploy
Further details about using these example projects can be found in [eval].
Gradle has a built in dependency management component that supports the Maven repository format. In order to configure a Gradle project to resolve dependencies declared in build.gradle file, a maven repository as shown in Minimal Gradle Setup has to be declared
repositories {
maven {
url "http://localhost:8081/nexus/content/groups/public"
}
}
These minimal settings allow Gradle to download the declared dependencies.
The above setup is specific to each project. Alternatively an init.gradle file placed e.g., in ~/.gradle can establish the repository as the source for dependencies in all projects. A simple implementation could look like
allprojects {
ext.RepoConfigurator = {
maven {
url = uri('http://localhost:8081/nexus/content/groups/public') }
}
buildscript.repositories RepoConfigurator
repositories RepoConfigurator
Other setup could be an expansion of the following example allowing file system based repostories:
/**
* init.gradle file for development using the Nexus Repository Manager as proxy repository
*
* @author Manfred Moser <manfred@simpligility.com
*/
apply plugin:NexusRepositoryPlugin
class NexusRepositoryPlugin implements Plugin<Gradle> {
final static String LOG_PREFIX = "init.gradle/NexusRepositoryPlugin:"
final Closure NexusConfig = {
maven {
name = 'standard-nexus'
url = 'http://localhost:8081/nexus/content/groups/public'
}
// if required you can add further repositories or groups here
// and they will be left intact if the name starts with standard-
// although it is better to just add those repositories in Nexus
// and expose them via the public group
}
final Closure RepoHandler = {
all { ArtifactRepository repo ->
if (repo.name.toString().startsWith("standard-") ) {
println "$LOG_PREFIX $repo.name at $repo.url activated as repository."
} else {
if (repo instanceof MavenArtifactRepository) {
remove repo
println "$LOG_PREFIX $repo.name at $repo.url removed."
} else {
println "$LOG_PREFIX $repo.name kept (not a Maven repository)."
}
}
}
}
void apply(Gradle gradle) {
// Override all project specified Maven repos with standard
// defined in here
gradle.allprojects{ project ->
println "$LOG_PREFIX Reconfiguring repositories."
project.repositories RepoHandler
project.buildscript.repositories RepoHandler
project.repositories NexusConfig
project.buildscript.repositories NexusConfig
}
}
}
Gradle init scripts can be much more powerful and customized and are explained with more examples in the official Gradle documentation.
To deploy build outputs to a repository with the uploadArchives task, user authentication can be declared in e.g., gradle.properties:
nexusUrl=http://localhost:8081/nexus nexusUsername=admin nexusPassword=admin123
and then used in the uploadArchives task with a mavenDeployer
configuration from the Maven plugin:
uploadArchives {
repositories {
mavenDeployer {
repository(
url: "${nexusUrl}/content/repositories/releases") {
authentication(userName: nexusUsername, password: nexusPassword)
}
snapshotRepository(
url: "${nexusUrl}/content/repositories/snapshots") {
authentication(userName: nexusUsername, password: nexusPassword)
}
}
}
}
Full example projects can be found in the gradle folder of the documentation examples project. A full build of the simple-project, including downloading the declared dependencies and uploading the build output to repository manager can be invoked with
cd gradle/simple-project gradle upload
Further details about using these example projects can be found in [eval].
sbt has a built in dependency management component and defaults to the Maven repository format. In order to configure a sbt project to resolve dependencies declared in build.sbt file, a resolver as shown in Minimal SBT Configuration has to be declared
resolvers += "Nexus" at "http://localhost:8081/nexus/content/groups/public"
These minimal settings allow sbt to download the declared dependencies.
To deploy build outputs to a Nexus repository with the publish task, user credentials can be declared in the build.sbt file:
credentials += Credentials("Sonatype Nexus Repository Manager",
"nexus.scala-tools.org", "admin", "admin123")
|
Tip
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The credentials string should never change, as third-party clients depend on it |
And then used in the publishTo configuration:
publishTo <<= version { v: String =>
val nexus = "http://localhost:8081/nexus/"
if (v.trim.endsWith("SNAPSHOT"))
Some("snapshots" at nexus + "content/repositories/snapshots")
else
Some("releases" at nexus + "content/repositories/releases")
Further documentation can be found in the sbt documentation on publishing.
Leiningen has a built in dependency management component and defaults to the Maven repository format. As a build tool it is mostly used for projects using the Clojure language. Many libraries useful for these projects are published to the Clojars repository.
If you want use Nexus with Leiningen, first create two new Maven 2 proxy repositories in Nexus with the remote URL http://clojars.org/repo/. One of these should have the Repository Policy set to Release and the other should have policy Snapshot. Then add both to your Maven 2 public group.
In order to configure a Leinigen project to resolve dependencies declared in the project.clj file, a mirrors section overriding the built in central and clojars repositories as shown in Minimal Leiningen Configuration has to be declared.
:mirrors {
"central" {
:name "Nexus"
:url "http://localhost:8081/nexus/content/groups/public"
:repo-manager true
}
#"clojars" {
:name "Nexus"
:url "http://localhost:8081/nexus/content/groups/public"
:repo-manager true}
}
These minimal settings allow Leiningen to download the declared dependencies.
To deploy build outputs to a Nexus repository with the deploy command, the target repositories have to be add to project.clj as deploy-repositories. This avoids Leiningen checking for dependencies in these repositories, which is not necessary, since they are already part of the Nexus public repository group used in mirrors.
:deploy-repositories [
["snapshots"
"http://localhost:8081/nexus/content/repositories/snapshots"]
["releases"
"http://localhost:8081/nexus/content/repositories/releases"]
]
User credentials can be declared in ~/.lein/credentials.clj.gpg or will be prompted for.
Further documentation can be found on the Leiningen website.