I'm trying to get Selenium tests to work when they are executed by Hudson, but I have not been successful so far. Hudson is running on Ubuntu, and Selenium is unable to open display.

Command I use for launching the build is:

mvn clean selenium:xvfb install

error log:

[INFO] [selenium:xvfb {execution: default-cli}]
[INFO] Starting Xvfb...
[INFO] Using display: :20
[INFO] Using Xauthority file: /tmp/Xvfb4467650583214148352.Xauthority
Deleting: /tmp/Xvfb4467650583214148352.Xauthority
xauth:  creating new authority file /tmp/Xvfb4467650583214148352.Xauthority
Created dir: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium
Launching Xvfb
Waiting for Xvfb...
[INFO] Redirecting output to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/xvfb.log
Xvfb started
...
[INFO] [selenium:start-server {execution: start}]
Launching Selenium Server
Waiting for Selenium Server...
[INFO] Including display properties from: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/display.properties
[INFO] Redirecting output to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/server.log
[INFO] User extensions: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/selenium/user-extensions.js
Selenium Server started
[INFO] [selenium:selenese {execution: run-selenium}]
[INFO] Results will go to: /var/lib/hudson/jobs/Selenium/workspace/selenium/target/results-firefox-suite.html
...
<~30 seconds pause>
...
Error: no display specified
...

pom.xml:

<groupId>org.codehaus.mojo</groupId>
<artifactId>selenium-maven-plugin</artifactId>
<version>1.0.1</version>
<executions>
    <execution>
        <id>start</id>
        <phase>pre-integration-test</phase>
        <goals>
            <goal>start-server</goal>
        </goals>
        <configuration>
            <logOutput>true</logOutput>
            <background>true</background>
            <port>5123</port>
        </configuration>
    </execution>

    <execution>
        <id>run-selenium</id>
        <phase>integration-test</phase>
        <goals>
            <goal>selenese</goal>
        </goals>
    </execution>

    <execution>
        <id>stop</id>
        <phase>post-integration-test</phase>
        <goals>
            <goal>stop-server</goal>
        </goals>
    </execution>

</executions>
<configuration>
    <browser>*firefox</browser>
    <suite>src/test/selenium/suite.html</suite>
    <startURL>http://localhost:${env.port}</startURL>
</configuration>

I've also tried to get it working by adding execution for xvfb, but also it failed.