Over the last year or so, I’ve worked to integrate xvfb into the projects I work with at the office and in the community to allow the execution of truly headless builds for Flex-based applications. Since the Flash Player and AIR require a windowing environment and typically unit and integration tests require this environment to be executed, integrating Flex into a CI process on Linux gets pretty hairy without having X-Windows support. Recently I’ve found myself switching from xvfb to Xvnc to more easily support headless builds in Flex. VNC server packages are pretty ubiquitous for most Linux distros, so getting something installed is pretty simple. What took me a couple of steps was getting setup based on the configuration of my CI server. In an effort to make searching a little simpler, here are the steps for using the Xvnc-plugin with Hudson on Ubuntu Desktop 8.10 with the default Tomcat 6 installation:
- Install the vnc4server package (i.e. – “apt-get install vnc4server”).
- Assuming the Ubuntu installation came with Tomcat 6 and is setup to run as the tomcat6 system user, do the following:
- Execute vncpassword as any user, following the prompts to set a password to be used by the “vncserver” command. This will create the “~/.vnc/password” file needed to run the vncserver command.
- Copy the file at ~/.vnc/password to /usr/shared/tomcat6/.vnc/password which is the default home directory for the tomcat6 user on the standard install of Ubuntu Desktop.
- Change the ownership rights on the “password” file to be owned and created by the “tomcat6″ user (i.e. – chown tomcat6:tomcat6 /usr/shared/.vnc/password)
- Edit /etc/init.d/tomcat6, adding a line to set the HOME environment variable to “/usr/shared/tomcat6″ (i.e. – export HOME=/usr/shared/tomcat6). Since “tomcat6″ is setup as a system user, from what I can tell, this environment variable is not set by default when a process is running as this user. The “vncserver” command will need this variable to determine where the “password” file is located to launch its process.
- If Tomcat is running as a standard user, execute the “vncserver” command using any display number (e.g. – vncserver :99) as the user. The command will force a prompt to enter a password to use for the server which will create the “~/.vnc/password” file with the appropriate ownership rights in the appropriate home directory.
- In Hudson, install the Xvnc-plugin for Hudson (http://wiki.hudson-ci.org/display/HUDSON/Xvnc+Plugin)
- OPTIONAL: In Hudson, under “Manage Hudson” -> “Configure system” -> “Xvnc”, set the “Base display number” field to 99. This is the base display number xvfb-run uses and I’m partial to reusing this setting.
- Under the configuration for you CI build, check the box labeled Run Xvnc during build.
- If all goes as expected, then your build should kick off the “vncserver :99″ command, set the DISPLAY environment variable to 99, execute your build to completion, and then execute “vncserver -kill :99″ to kill the Xvnc process.
Based on these steps, I’m am currently building Xvnc support into the FlexUnit4 Ant task for those who don’t use Hudson and can’t take advantage of the Xvnc-plugin. The Xvnc support is a basic mirror of what the plugin for Hudson aims to provide. Hopefully someone will find this footwork useful and save some time. I’m by no means a Linux guru, so if anyone has more insight, please feel free to share so others can benefit from your knowledge as well.
Happy building!
UPDATE: I’ve now tested and deployed the Xvnc support for the FlexUnit Ant task. Hopefully this will help anyone who’s not using Hudson but wants to take advantage of headless FlexUnit test executions using Xvnc.
