settings.xml for SonarQube to be placed into the $HOME/.m2 folder (maven's configuration folder)

settings.xml

<settings>
    <profiles>
        <profile>
            <id>sonar</id>
            <activation>
                <activeByDefault>true</activeByDefault>
            </activation>
            <properties>
                <!-- Example for MySQL-->
                <sonar.jdbc.url>
                  jdbc:mysql://localhost:3306/sonar?useUnicode=true&amp;characterEncoding=utf8
                </sonar.jdbc.url>
                <sonar.jdbc.username>sonar</sonar.jdbc.username>
                <sonar.jdbc.password>sonar</sonar.jdbc.password>

                <!-- Optional URL to server. Default value is http://localhost:9000 -->
                <sonar.host.url>
                  http://localhost:9000
                </sonar.host.url>
            </properties>
        </profile>
     </profiles>
</settings>