src/site/apt/guides/mini/guide-configuring-maven.apt

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 Guide to Configuring Maven
 ------
 Brett Porter
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 12 April 2005
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Configuring Maven

  Maven configuration occurs at 3 levels:

   * <Project> - most static configuration occurs in <<<pom.xml>>>

   * <Installation> - this is configuration added once for a Maven installation

   * <User> - this is configuration specific to a particular user

  The separation is quite clear - the project defines information that applies to the project, no matter who is
  building it, while the others both define settings for the current environment.

  <<Note:>> the installation and user configuration cannot be used to add shared project information -
  for example, setting <<<\<organization\>>>> or <<<\<distributionManagement\>>>> company-wide.

  For this, you should have your projects inherit from a company-wide parent <<<pom.xml>>>.

  ~~TODO: versioning doc that discusses this

  You can specify your user configuration in <<<$\{user.home\}/.m2/settings.xml>>>. A
  {{{../../maven-settings/settings.html}full reference}} to the configuration file is available. This section will show how
  to make some common configurations. Note that the file is not required - defaults will be used if it is not found.

* Configuring your Local Repository

  The location of your local repository can be changed in your user configuration.
  The default value is <<<$\{user.home\}/.m2/repository/>>>.

-------------
<settings>
  ...
  <localRepository>/path/to/local/repo/</localRepository>
  ...
</settings>
-------------

  <<Note:>> The local repository must be an absolute path.

* Configuring a Proxy

  Proxy configuration can also be specified in the settings file.

  For more information, see the {{{./guide-proxies.html} Guide to using a Proxy}}.

* Configuring Parallel Artifact Resolution

  By default, Maven 2.1.0+ will download up to 5 artifacts (from different groups) at once. To change the size of the thread pool, start Maven using
  <<<-Dmaven.artifact.threads>>>. For example, to only download single artifacts at a time:

----
mvn -Dmaven.artifact.threads=1 clean install
----

  You may wish to set this option permanently, in which case you can use the <<<MAVEN_OPTS>>> environment variable. For example:

----
export MAVEN_OPTS=-Dmaven.artifact.threads=3
----

* Security and Deployment Settings

  Repositories to deploy to are defined in a project in the <<<\<distributionManagement\>>>> section.
  However, you cannot put your username, password, or other security settings in that project. For that reason,
  you should add a server definition to your own settings with an
  <<<id>>> that matches that of the deployment repository in the project.

  In addition, some repositories may require authorization to download from, so the corresponding settings can
  be specified in a <<<server>>> element in the same way.

  Which settings are required will depend on the type of repository you are deploying to. As of the first release,
  only SCP deployments and file deployments are supported by default, so only the following SCP configuration
  is needed:

-------------
<settings>
  ...
  <servers>
    <server>
      <id>repo1</id>
      <username>repouser</username>
      <!-- other optional elements:
        <password>my_login_password</password>
        <privateKey>/path/to/identity</privateKey> (default is ~/.ssh/id_dsa)
        <passphrase>my_key_passphrase</passphrase>
      -->
    </server>
  ...
  </servers>
  ...
</settings>
-------------

  To encrypt passwords in these sections, refer to {{{./guide-encryption.html} Encryption Settings}}.

* Using Mirrors for Repositories

  Repositories can be declared inside a project, which means that if you have your own custom repositories, those
  sharing your project easily get the right settings out of the box. However, you may want to use an alternative
  mirror for a particular repository without changing the project files.

  Some reasons to use a mirror are:

   * There is a synchronized mirror on the internet that is geographically closer and faster

   * You want to replace a particular repository with your own internal repository which you have greater control over

   * You want to run maven-proxy to provide a local cache to a mirror and need to use its URL instead

  To configure a mirror of a given repository, you provide it in your settings file, giving the new repository its own
  <<<id>>> and <<<url>>>, and specify the <<<mirrorOf>>> setting that is the ID of the repository you are using a mirror
  of. For example, the <<<id>>> of the main Maven repository included by default is <<<central>>>, so to use a Spanish
  mirror, you would configure the following:

-------------
<settings>
  ...
  <mirrors>
   <mirror>
      <id>cica.es</id>
      <name>Spanish Mirror of http://repo1.maven.org/maven2/</name>
      <url>http://ftp.cica.es/mirrors/maven2</url>
      <mirrorOf>central</mirrorOf>
    </mirror>
  ...
  </mirrors>
  ...
</settings>
-------------

  More info about mirrors is available in the {{{./guide-mirror-settings.html}Guide to Mirror Settings}}.

* Profiles

 Repository configuration can also be put into a profile. You can have multiple
 profiles, with one set to active so that you can easily switch environments.
 Read more about profiles in {{{../introduction/introduction-to-profiles.html}Introduction to Build Profiles}}.