Take artifacts from multiple repositories with Maven - maven

How can I configure a maven project to take one of the artifacts from a different repository?
I would like to include this in the project https://github.com/twitter/hadoop-lzo but I can find it only in the twitter repository, not on the central maven repository.

You can set the repositories you want to use in your settings.xml, or in your POM.
If you have a team working on the project, you might want to put this in the POM so everybody has the conf.
You can do it like :
<repositories>
<repository>
<id>Maven Central</id>
<url>http://repo1.maven.org/maven2/</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
.... other repos
</repositories>

Related

How to add more sources for Find Jar on Web in IntelliJ

When I right-click a missing import, I have an option of "Find Jar on Web", but the Jars in the list are outdated. For example, the newest ant jar on the list is ant-1.7.1.jar, but I know that ant-1.10.1.jar is available from Maven Central.
How can I add more "sources" to the search of IntelliJ?
This happens because the repositories is outdated in your IntelliJ, so, you can update with these steps, go to:
Preferences > Build, Execution, Deployment > Maven > Repositories
Choose the Remote repository entry and click on Update button, this action takes some minutes, after of that, do the same with your Local repository, IntelliJ will be able to retrieve the last versions of your dependencies.
UPDATE
To view the remote repositories in IntelliJ, you can add in your settings.xml file (check this) or directly in your pom.xml file of your project.
This is the structure for your settings.xml file:
<project>
<repositories>
<repository>
<id>maven-central</id>
<url>http://repo.maven.apache.org/maven2</url>
</repository>
</repositories>
</project>
And this is the structure for your pom.xml file:
<dependencies>
...
</dependencies>
<repositories>
<repository>
<id>codehausSnapshots</id>
<name>Codehaus Snapshots</name>
<releases>
<enabled>false</enabled>
<updatePolicy>always</updatePolicy>
<checksumPolicy>warn</checksumPolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
<checksumPolicy>fail</checksumPolicy>
</snapshots>
<url>http://repo.maven.apache.org/maven2</url>
<layout>default</layout>
</repository>
</repositories>
After of add this configuration, IntelliJ will be able to detect the new repository.
Notice: The updated specified in your pom.xml file (or inherited from parent project's pom and settings.xml)

Retrieving dependencies from maven repository

So for my maven project I require jar dependencies that are available in public repositories and also jar dependencies that are on our company internal repository.
How do I configure my pom.xml so that I will retrieve the dependencies from public repositories and our company internal repository without synchronizing and uploading the stuff from public repos to the company internal repository.
In your settings.xml, which is usually in HOME_DIR/.m2 you need to add the company repository, maven central is included by default.
In the example below it will look for your artifact in each repo in order, starting with maven central.
<profile>
<id>extras</id>
<repositories>
<repository>
<id>release</id>
<name>libs-release</name>
<url>http://internal.corp:8091/artifactory/libs-release</url>
</repository>
<repository>
<id>snapshot</id>
<name>libs-snapshot</name>
<url>http://internal.corp:8091/artifactory/libs-snapshot-local</url>
</repository>
<repository>
<id>codelds</id>
<url>https://code.lds.org/nexus/content/groups/main-repo</url>
</repository>
<repository>
<id>spring-milestone</id>
<name>Spring Maven MILESTONE Repository</name>
<url>http://repo.springsource.org/libs-milestone</url>
</repository>
</repositories>
</profile>
I would also say that I set up our corporate repository so that is has a virtual repository to maven central. This means as people use artifacts they will be stored in the company repository. This is normal practice.

How maven handle multiple <repository> configurations?

I am getting more and more comfortable with maven. But still some questions.
I have multiple <repository> in my pom.xml.
How will maven handle these repos when downloading artifacts? Will it search by the declaration order?
Besides the explicitly declared ones, will maven still check the default central repo at http://repo.maven.apache.org/maven2/?
If something cannot be found within the explicitly configured repo, will maven fallback to the default central repo?
Is it good to use multiple repos? I am kind of worried about inconsistency.
Below is the <repositories> section of my pom.xml:
<repositories>
<repository>
<id>ibiblio-central-repo</id>
<layout>default</layout>
<name>ibiblio-central-repo</name>
<releases>
<checksumPolicy>warn</checksumPolicy>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<url>http://maven.ibiblio.org/maven2/</url>
</repository>
<repository>
<id>oschina-central-repo</id>
<layout>default</layout>
<name>oschina-central-repo</name>
<releases>
<checksumPolicy>warn</checksumPolicy>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<url>http://maven.oschina.net/content/groups/public/</url>
</repository>
<repository>
<id>oschina-central-repo-3rd-party</id>
<layout>default</layout>
<name>oschina-central-repo-3rd-party</name>
<releases>
<checksumPolicy>warn</checksumPolicy>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<url>http://maven.oschina.net/content/repositories/thirdparty/</url>
</repository>
</repositories>
How will maven handle these repos when downloading artifacts? Will it
search by the declaration order?
Order of declaration as part of the merged settings (see next answer). I have found this JIRA ticket providing further details.
Besides the explicitly declared ones, will maven still check the
default central repo at http://repo.maven.apache.org/maven2/?
Yes, as it will be provided by the Maven super POM, implicit parent of all Maven Pom (here an official example), unless specified in your settings.xml (if you override the repository id specified in the super POM). You can use the Maven Help Plugin to get the effective settings Maven will apply to your build and the effective pom maven will actually (effectively) run.
As documented here, the repositories element is inherited.
If something cannot be found within the explicitly configured repo,
will maven fallback to the default central repo?
As above. Moreover, you could also influence this mechanism via any configured Maven mirror. You could, for instance, redirect Maven to your company repository (see below) instead of looking up on the default one.
Is it good to use multiple repos? I am kind of worried about
inconsistency.
You probably don't need many configured repositories, but you might need more than one if the dependencies you are looking for are not provided by the default repository. A good approach would be to have an enterprise Maven repository (i.e. Artifactory, Nexus) and make your local settings only point to it. Then, configure the internal Maven repository to point to other repositories, in a centralized (and governed) manner.

Get dependencies from multiple repo's

Is it possible to download dependencies in maven using multiple plugin-repos?
I have my settings.xml configured to get dependencies from a custom repo and because of this, i am unable to get dependencies from the main maven repo server.
Is this possible to setup more then one plugin Repo?
Here is what i have setup so far for my custom repo:
</profiles>
<profile>
<id>custom-config</id>
<repositories>
<repository>
<id>custom-snapshots</id>
<name>customSnapshots</name>
<releases>
<enabled>false</enabled>
<updatePolicy>always</updatePolicy>
<checksumPolicy>warn</checksumPolicy>
</releases>
<snapshots>
<enabled>true</enabled>
<updatePolicy>never</updatePolicy>
<checksumPolicy>fail</checksumPolicy>
</snapshots>
<url>http:/custom/repo</url>
<layout>default</layout>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>custom-plugins</id>
<urlhttp:/custom/repo/public-snapshots</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>true</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</profile>
</profiles>
I have not included the dependencies here, but I am unable to pull and resolve some library dependencies.
The maven repo that I use is http://mvnrepository.com/ but I dont have details on the exact repo settings to use as the one I defined for a custom one.
The default maven repository is called "central". Its url is: http://repo1.maven.org/maven2/ or nowadays: http://repo.maven.apache.org/maven2/
But it is usually configured as mirrorOf. If you create a repository in your settings.xml and give it the id *central" it will replace it.
So I wonder why you can't resolve dependencies from there. Usually adding a repository in settings.xml does not turn of central.
could you execute mvn help:effective-settings and mvn help:effective-pom and have a loook at all repositories, profiles and mirrorOf elements in the xml? central should be there.
I would also recommend using a Maven proxy like Nexus or Artifactory. It simplifies a lot of things within a company.

Maven repository lookup order

We have an internal Apache Archiva based repository and we have configured the repositories tag in pom.xml to be as follows. Can I assume that all dependency access will get resolved by internal repository if you have access to it and will get resolved by other repositories listed below, if internal repository is down for a certain reason.
<repositories>
<repository>
<id>internal</id>
<name>Internal Repository</name>
<url>http://192.168.1.2/archiva/repository/internal</url>
</repository>
<repository>
<id>jboss</id>
<url>https://repository.jboss.org/nexus/content/repositories/releases</url>
<releases>
<enabled>true</enabled>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
....
</repositories>
EDIT:
I want to do away with the .m2/settings.xml file. I want to define this in my pom.xml file, so that if my repository manager is UP and running I would want the runtime to connect there, else would want to fallback into the other repositories. Would this be possible?
Maven 3.0 had it fixed as you can see in Maven developer's Jira below. The lookup will be done in the order they are declared.
https://issues.apache.org/jira/browse/MNG-4400

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