continuous integration

Jenkins CI (the new name of Hudson) is a very popular continuous integration system. It can be used to monitor the execution of various jobs, including but not limited to compilation, packaging, testing and deploying of software. Also, it is very easy to configure and comes with a great set of (3rd party) plugins.
I use Jenkins in a number of ways: to monitor and prepare & test new releases of Phing, monitor various internal processes (such as backup logs), and build and deploy various other projects that I work on.

In this post I will expand on some of the techniques discussed in an earlier IBM developerWorks article, to (automatically) build and deploy Java J2EE applications to a WebSphere server. The code fragments listed below are contained in a downloadable archive that you’ll be able to download at the end of this post.

Requirements

To get started, you’ll need to have installed:

• Jenkins CI with the following plugins (can be installed via “Manage Jenkins” -> “Manage Plugins”):
  • Copy Artifact
  • Blame Subversion
  • Parameterized Trigger
  • RAD Builder
• Ant Contrib
• IBM Rational Application Developer
• A test/staging installation of the WebSphere Application Server

This post assumes you have some knowledge of Ant, and are able to install Jenkins and IBM RAD.

Job configuration

For this particular case we will configure two Jenkins CI jobs: one job will build number of artifacts (in this case, .ear files) from source code contained in a version control repository, and another job will deploy the generated artifacts to a WebSphere server. This deployment job will be triggered when the build job completes (successfully).

Build job

Create a new “free-style” job, and configure it as you normally would. Make sure you check out the source code to the src directory, within the job workspace.

Then, click “Add build step”, and select the IBM RAD plugin. The field “build file” should contain the path to the build file we will use (Builder\build.xml in the archive). The field “RAD workspace” points to a directory (within the job’s workspace) where a RAD workspace will be created, in this case (see the build file below) we use the path “rad-workspace”. The other settings can be left at their default values.

Build file

The Jenkis RAD builder plugins creates a fresh workspace, similar to the workspace that is used inside RAD (or Eclipse). To prepare this workspace with the right configuration settings, we use the task workspacePreferenceFile. The input for this task is a simple preferences file, either text format (key=value pairs, see sample), or the Eclipse .epf format.

compiler.compliance=1.5
compiler.source=1.5
classpath.SOMELIBRARY=D:\Development\somelibrary.jar

The task workspacePreferenceFile is then called in the setup-workspace target.
<target name="setup-workspace"
	description="Sets the preferences for the current workspace">

	<!-- Debug information -->
	<echo level="verbose" message="rad.preferences.filename=${rad.preferences.filename}"/>

	<!-- Set the workspace preferences -->
	<workspacePreferenceFile
		PreferenceFileName="${rad.preferences.filename}"
		useEclipsePrefs="false"
		overwrite="true"/>
	<echo level="verbose" message="workspacePreferenceFile done"/>
</target>

Next, the code that has previously been checked out by Jenkins will need to be copied to this new workspace. The properties copy.from.path and copy.excludes (optional, comma-separated list of excluded patterns) are set in the IBM RAD builder configuration (build job).
<target name="copy-projects"
description="Copies the content of a folder to the current workspace">

	<!-- Debug information -->
	<echo level="verbose" message="copy.from.path=${copy.from.path}"/>
	<echo level="verbose" message="workspace=${workspace}"/>

	<copy
		todir="${workspace}"
		includeEmptyDirs="true">
		<fileset dir="${copy.from.path}" excludes="${copy.excludes}">
			<include name="**/**"/>
		</fileset>
	</copy>
	<echo level="verbose" message="copy done"/>
</target>

Now that the workspace is configured and contains the projects we’d like to build, it’s time to make RAD aware of the contents by actively importing each project – this is done by calling the projectImport task. The list of projects is generated by scanning the workspace for directories that contain a .project file.
<target name="import-projects"
	description="Imports a set of projects into the current workspace">
	
	<!-- Retrieve list of projects (folders containing a .project file) -->
	<dirset id="projects.list" dir="${workspace}">
		<include name="*"/>
		<present targetdir="${workspace}">
			<mapper type="glob" from="*" to="*/.project" />
		</present>
	</dirset>
	<pathconvert property="projects.name" refid="projects.list" pathsep=",">
		<map from="${workspace}" to=""/>
	</pathconvert>
	
	<!-- Debug information -->
	<echo level="verbose" message="projects.name=${projects.name}"/>

	<!-- Import the projects -->
	<foreach
		list="${projects.name}"
		target="import-project"
		param="project.name"/>
</target>

<target name="import-project">
	<!-- Debug information -->
	<echo level="verbose" message="project.name=${project.name}"/>
	<echo level="verbose" message="workspace=${workspace}"/>

	<projectImport
		projectName="${project.name}"
		projectLocation="${workspace}/${project.name}"/>
	<echo level="verbose" message="projectImport ${project.name} done"/>
</target>

The most important part of the build file is the target build-workspace, which calls the task workspaceBuild to perform a full build. By default, this task will fail the build if any (compiler) errors are encountered – this is what we want.
<target name="build-workspace"
	depends="setup-workspace,copy-projects,import-projects"
	description="Builds the current workspace">

	<!-- Fully build the workspace -->
	<workspaceBuild
		BuildType="Full"/>
	<echo level="verbose" message="workspaceBuild done"/>
</target>

Hopefully, there are no errors, and we are in a situation where all the projects have been built successfully. Time to generate some artifacts!

The target export-ear first updates the (generated) manifest file with a few Jenkins parameters, such as build number, SVN revision, job name, and the current date. This data is a useful (extra) aid to identify the version / origin of deployed code (please note that you can also use the fingerprinting functionality for this, see below).
We then call the earExport task to create a .ear file, identical to choosing “Export” -> “EAR file” within RAD.
<target name="export-ear"
	description="Exports the EAR defined by the ear.project.name/ear.filename properties">
	
	<property name="ear.filename" value="${workspace}${ear.project.name}-${env.BUILD_NUMBER}-${env.BUILD_ID}.ear"/>
		
	<!-- Update the manifest with Jenkins build info -->
	<echo>Updating manifest</echo>
	<tstamp>
		<format property="TODAY" pattern="yyyy-MM-dd HH:mm:ss"/>
	</tstamp>
	<manifest
		file="${workspace}${ear.project.name}/META-INF/MANIFEST.MF"
		mode="update">
		<attribute name="Built-By" value="Jenkins CI"/>
		<attribute name="Implementation-Version" value="#${env.BUILD_NUMBER} - r${env.SVN_REVISION} - ${env.BUILD_ID}"/> 
		<attribute name="Implementation-Title" value="${env.JOB_NAME}"/>
		<attribute name="Built-Date" value="${TODAY}"/>
	</manifest>
	
	<!-- Debug information -->
	<echo level="verbose" message="ear.filename=${ear.filename}"/>
	<echo level="verbose" message="ear.project.name=${ear.project.name}"/>
	
	<!-- Export the EAR project as an EAR file -->
	<earExport
		EARProjectName="${ear.project.name}"
		EARExportFile="${ear.filename}"
		ExportSource="false"
		IncludeProjectMetaFiles="false"
		Overwrite="true"/>
	<echo level="verbose" message="earExport ${ear.filename} done"/>
</target>

When the RAD builder finishes succesfully, the build part of the job is completed and a number of artifacts (.ear files) will have been generated.

In the post-build actions we make sure the generated artifacts are scooped up and archived. This makes sure that artifacts are kept even if the original build was (re)moved. Additionally, we enable the recording of fingerprints on each artifact. In essence, this will calculate and store a hash value (MD5 or similar) based on the contents of each file. Should we need to identify a particular artifact at some point in the future, we can simply upload that file to Jenkins, let it calculate a hash value, and match that hash value against its internal fingerprint database. If there’s a match, Jenkins will tell us the job name, build number, date, and any other useful information.
Finally, we call the deploy job using the parameterized trigger plugin. In this case, we do not override any of the default parameters (see below). Should you want to, click “Add parameter”, then “Predefined parameters”. Enter the parameters (key=value pairs) in the text area.
Deploy job
As stated before, the deployment job copies generated artifacts from the build job, and installs the artifacts on a (test/staging) WebSphere server. To achieve this, the job calls the wsadmin tool and executes a single JACL script.
An important part of this job are the predefined parameters, telling the JACL script which SOAP connection to use, and which node / cell / server name / virtual host to install the application to. In this case, each of these parameters has a default value – pointing to a default (local) testing server.

The build phase of the job consists of three separate build steps:

Remove any artifacts that were left by previous builds
Copy the artifacts generated by the last successful run of the build job
Execute ws_ant (Ant with WebSphere functionality/classes preloaded), which in turn uses wsadmin to run a JACL script.


The JACL script has two modes of operation. First, it stops and uninstalls the previous version of the application we are trying to install. Errors that occur during this first part are ignored.
set appManager [$AdminControl queryNames cell=$cell,node=$node,type=ApplicationManager,process=$server,*]

catch { $AdminControl invoke $appManager stopApplication $appname } result

$AdminConfig save

$AdminApp uninstall $appname

$AdminConfig save

In the second part of the script, the application is installed on the specified node/cell/server/virtual host. Then, after giving the application server some time to process the installed artifact, the script starts the application. If this completes without errors the application is ready to use!
$AdminApp install "$workspace/$earfile" "-node $node -cell $cell -server $server -verbose -defaultbinding.virtual.host $vhost -usedefaultbindings"

$AdminConfig save

set ready false
set retries 0

while {$retries < 20} {
	incr retries
	set ready [$AdminApp isAppReady $appname]
	puts "AdminApp isAppReady: $ready ($retries)"
	
	if {$ready} { break }
	
	sleepDelay 5
}

set appManager [$AdminControl queryNames node=$node,cell=$cell,type=ApplicationManager,process=$server,*]

$AdminControl invoke $appManager startApplication $appname

$AdminConfig save

Conclusion / thoughts
In this post you’ve seen how to use Jenkins CI to build (through IBM RAD) and deploy (through IBM wsadmin) a J2EE application to a WebSphere server. I hope these exampless can serve as a starting point for your forays into the exciting world of Jenkins CI.
Comments and suggestions are very welcome!
Downloads

WebSphere Demo Files