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Table of Contents
Continuous integration is a process in which all development work is integrated at a predefined time or event and the resulting work is automatically tested and built. The idea is that development errors are identified very early in the process.
Jenkins is one open source tool to perform continuous integration. The basic functionality of Jenkins is to execute a predefined list of steps based on a certain trigger.
The trigger might for example be an change in a version control system or a time based trigger, e.g., a build every 20 minutes.
The list of steps can for example include:
perform a software build with Apache Maven or Gradle
Run a shell script
Archive the build result
Afterwards start the integration tests
Jenkins also monitors the execution of the steps and allows to stop the process if one of the steps fails. Jenkins allows to notify users about the build success or failure.
Jenkins can be started via the command line or can run in a web application server. Under Linux you can also install Jenkins as a system service.
Jenkins provides Debian/Ubuntu packages which install Jenkins and register Jenkins as start service. See the following URL for details.
Jenkins stores all the settings, logs and build artifacts in its home
directory. The default installation directory is
This creates a
start script which starts Jenkins automatically at boot time.
If you start it locally, you find it running under the following URL: http://localhost:8080/
For most platforms you have native packages, see the Jenkins Homepage.
You can also start Jenkins directly via the command line with
java -jar jenkins*.war.
If you start it locally, you find it running
under the following URL:
To run it in your Tomcat server, put the .WAR file
directory. If you start
Tomcat, your Jenkins installation will be
If the jenkins.war is deployed in your
but cannot be started and the tomcat manager says
“FAIL - Application at
context path /jenkins could not be
”, you may need to grant
the permissons for
cd /usr/share/tomcat7 sudo mkdir .jenkins sudo chown tomcat7:nogroup .jenkins
This makes the .jenkins folder writable and Jenkins can use it.
If you want to install Jenkins in a web container, you can use, for example, Tomcat or Jetty. See the Apache Tomcat Tutorial.
In this example we use Apache Maven to build a simple Java project. Please see the Apache Maven tutorial for details.
We use Git in this example. Please see the Git tutorial for details.
Before using Jenkins you need to tell it where your JDK and ant installation is. Open Jenkins in your browser and click Manage Jenkins and then Configure System.
Enter the correct path to your JDK, Apache Ant and Maven and press thebutton below. Jenkins can also install these for your automatically.
It is recommended to secure Jenkins. Manage Jenkins and then Configure Global Security. Select the Enable security flag. The easiest way is to use Jenkins own user database. Create at least the user "Anonymous" with read access. Also create entries for the users you want to add in the next step.
On the login page, select Create an account to create the users you just gave access.
Go to Manage Jenkins, Manage and Assign Roles and then Assign Roles to grant the newly created user additional access rights.
to define access restrictions in detail.
Pattern is a regex value of the job name.
The following grants unregistered users
read-only access to your build jobs that
start with the
M-MASTER prefix and only those.
Jenkins can be extended via additional plug-ins with more functionality. You can configure your plug-ins via the→ link.
The following table is a summary of commonly used plug-ins.
Table 1. Jenkins plug-ins
|Git Plugin||This plugin allows use of Git as a build SCM.||https://wiki.jenkins-ci.org/display/JENKINS/Git+Plugin|
This plugin allows projects to run xvnc during a build. This allows for example to run tests which requires a display to run on a virtual display. To use this plug-in you need to connect once to your vncserver on the command line to provide a password. Use for example the following commands.
# install vncserver apt-get install vnc4server # switch to jenkins user sudo su jenkins # connect to vncserver which creates the password vncserver :10
Jenkins supports the Git version control system via a plugin. Select the Git Plugin.→ link. Here you have to install the
To clone a Git repostory via Jenkins you need to enter the email
user name for your Jenkins system. For this switch into your job
directory and run the
# Need to configure the Git email and user for the Jenkins job # switch to the job directory cd /var/lib/jenkins/jobs/Android/workspace # setup name and email sudo git config user.name "jenkins" sudo git config user.email "firstname.lastname@example.org"
The build of a project is handled via jobs in Jenkins. Select New Item from the menu
Afterwards enter a name for the job and and select Freestyle Job. Press to create a new Job in Jenkins.
The next page allows you to configure your job. If you for example using Git, enter the URL to the Git repository. If the repository is not public, you may also need to configure the credentials.
Specify when and how your build should be triggered. The following example polls the Git repository every 15 min and triggers a build, if something has changed in the repo.
I typically delete the workspace before a build to avoid any side-effect. In the Build section you can add a build step, e.g., a Maven build.
Press Save to finish the job definition. Press Build Now on the job page to validate the job works as expected.
After a while the job should go to green or blue (depending on your configuration), if successful. Click on the job and afterwards on Console Output to see the log file in case of an error or to validate that log looks as expected.
To create a build job on Jenkins you need to have a working build setup. See Android build tutorial.
Jenkins supports the automatic building and testing of Android applications. To start your tests on an emulator you can use the Android Emulator Plugin. The Android Emulator Plugin supporting starting and unlocking and blocks the build until the emulator has started.
A detailed description of this plugin can be found under the following URL: Android Emulator Plugin Jenkins page.
To install this plug-in use the→ link and search for "Android". Select it from the list and select to install it and restart Jenkins.
For automated tests it is good practice to have another job which executes the tests. This job can be connected to the build job of the application so that it runs automatically after this compile step.
To create an Android build job on Jenkins, select New Job, enter a job name and select the Build a free-style software project option.
You configure from where the source should be cloned.
You configure the emulator which should be started. Ensure that you do not select the Show emulator window option, as your build server should not depend on the availability of a display server.
You may see the following error message: "Error: Invalid --abi ... for the selected target" in the log of your job. In this case you have to install the desired Andoid images manually with the following command.
// run this as Jenkins user /var/lib/jenkins/tools/android-sdk/tools/android update sdk --no-ui
Use /var/lib/jenkins/tools/android-sdk/tools/android list targets to see what ABIs are installed. If no are listed manual install one.
Configure the Apache Ant build file, use the Advanced option to specify the location of the build file.
The Android Emulator Plugin supports a new job with the Build multi-configuration project option. This option allows you to test multiple emulator configurations at the same time. You can, for example, test different languages, densities, screen resolutions, etc.
Typically you have two Jobs, one for a simple build and test run and a multi-configuration project to test the build on different device configurations.
You can combine Android Emulator Plugin with the Amazon-EC2-Plug-in to run the build and the tests on several machines simultaneously.
Jenkins stores all the settings, logs and build artifacts in its home
directory, for example, in
under the default install location of Ubuntu.
To create a backup of your Jenkins setup, just copy this directory.
directory contains the individual jobs configured in the Jenkins
install. You can move a job from one Jenkins installation to another
by copying the corresponding job directory. You can also copy a job
directory to clone a job or rename the directory.
Clickbutton in the Jenkins web user interface to force Jenkins to reload configuration from the disk.
See Adminstration of Jenkins for details.
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