14.5. Configuring Maven Proxies and HTTP Proxies through settings.xml

Overview

You can optionally configure the Maven proxy using a standard Maven settings.xml file. For example, this approach is particularly convenient in a development environment, because it makes it possible to store your build time settings and your run time settings in one place.
The Maven settings.xml approach is not used by default. You must explicitly enable it.

Adding a remote Maven repository

A default settings.xml file is provided for you in InstallDir/etc/maven-settings.xml. To add a new remote Maven repository to the InstallDir/etc/maven-settings.xml file, open the maven-settings.xml file in a text editor and add a new repository XML element. For example, to create an entry for the Red Hat GA public Maven repository, add a repository element as shown: 
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" 
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
      xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
    ...
    <!--
        If org.ops4j.pax.url.mvn.repositories property is _prepended_ with '+' sign, repositories from all active
        profiles will be _appended_ to the list of searched remote repositories
    -->
    <profiles>
        <profile>
            <id>default</id>
            <repositories>
                <repository>
                    <id>redhat-ga-repository</id>
                    <url>https://maven.repository.redhat.com/ga</url>
                </repository>
            </repositories>
        </profile>
    </profiles>

    <activeProfiles>
        <activeProfile>default</activeProfile>
    </activeProfiles>

</settings>
Important
Do not forget to activate your profile, by adding an activeProfile element that references the profile ID (in this example, the profile ID is default).

Enabling the settings.xml configuration approach

To configure Fabric to read its Maven configuration from a Maven settings.xml file, perform the following steps:
  1. Configure the Maven repositories you need in the InstallDir/etc/maven-settings.xml file (see the section called “Adding a remote Maven repository”).
  2. Copy the Maven repositories from the io.fabric8.agent/org.ops4j.pax.url.mvn.settings property into the maven-settings.xml file (normally, you need to preserve access to these repositories). To see the list of repositories from the io.fabric8.agent/org.ops4j.pax.url.mvn.settings property in the default profile, enter the following Fabric8 command: 
    JBossFuse:karaf@root> profile-display default
    Follow the instructions in the section called “Adding a remote Maven repository” to add these repositories set in io.fabric8.agent/org.ops4j.pax.url.mvn.settings to the maven-settings.xml file (if they are not already present).
  3. (Optional) If you want to combine the list of repositories appearing in the maven-settings.xml file with the list of repositories from the io.fabric8.maven/io.fabric8.maven.repositories property, prepend a + sign to the list of repositories in io.fabric8.maven.repositories. For example: 
    io.fabric8.maven.repositories=+http://repo1.maven.org/maven2@id=maven.central.repo,https://maven.repository.redhat.com/ga@id=redhat.ga.repo,https://maven.repository.redhat.com/earlyaccess/all@id=redhat.ea.repo,https://repository.jboss.org/nexus/content/groupsea@id=fuseearlyaccess
  4. Delete the org.ops4j.pax.url.mvn.repositories property setting from the io.fabric8.agent PID in the default profile, using the following console command: 
    profile-edit --delete --pid io.fabric8.agent/org.ops4j.pax.url.mvn.repositories default
    When the repositories setting is absent, Fabric implicitly switches to the maven-settings.xml configuration approach.
    Note
    By default, this step simultaneously clears both the repository list used by the Fabric8 agent and the repository list used by the Maven proxy server (because the Maven proxy's repository list normally references the Fabric8 agent's repository list).

Changing the default location of Maven settings.xml

Fabric is pre-configured to use the InstallDir/etc/maven-settings.xml file. That is, the following settings are configured by default: 
io.fabric8.maven/io.fabric8.maven.settings = ${karaf.etc}/maven-settings.xml
io.fabric8.agent/org.ops4j.pax.url.mvn.settings = ${karaf.etc}/maven-settings.xml
If you need to customize the location of your Maven settings.xml file, edit the value of these properties in the default profile.

Configuring an HTTP proxy

To configure an HTTP proxy (which will be used when connecting to remote Maven repositories), open the etc/maven-settings.xml file in a text editor and add a new proxy XML element as a child of the proxies XML element. The definition of the proxy follows the standard Maven syntax. For example, to create a proxy for the HTTP (insecure) protocol with host, 127.0.0.1, and port, 3128, add a proxy element as follows: 
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" 
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
      xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
    ...
    <!--
        This is the place to configure http proxies used by Aether.
        If there's no proxy for "https" protocol, proxy for "http" will be used when accessing remote repository
    -->
    <proxies>
        <!--
        <proxy>
            <id>proxy</id>
            <host>127.0.0.1</host>
            <port>3128</port>
            <protocol>http</protocol>
            <username></username>
            <password></password>
            <nonProxyHosts>127.0.0.*|ensemble1|ensemble2|ensemble3</nonProxyHosts>
        </proxy>
        -->
    </proxies>
    ...
</settings>
You must remember to add the ensemble hosts (where the Maven proxy servers are running) to the list of HTTP non-proxy hosts in the nonProxyHosts element. This ensures that the Fabric8 agents do not attempt to connect to the Maven proxies through the HTTP proxy, but make a direct connection instead. In the preceding example, the ensemble host names are ensemble1, ensemble2, and ensemble3.
By default, HTTPS connections use the same proxy settings as the HTTP protocol. If you need separate configuration for HTTPS, you can optionally add another proxy element configured with the https protocol.

Reference

For a detailed description of the syntax of the Maven settings.xml file, see the Maven Settings Reference. But please note that not all of the features documented there are necessarily supported by Fabric.