Jenkins is an open source continuous integration (CI) tool written in Java. Continuous integration (CI) is the practice, in software engineering, of merging all developer working copies with a shared mainline several times a day. The main aim of CI is to prevent integration problems. Jenkins provides continuous integration services for software development. It is a server-based system running in a servlet container such as Apache Tomcat.

1. Jenkins CI
Ruchi Agarwal
Sr Software Consultant
Knoldus Software LLP

2. Index:

About Jenkins CI

Install Jenkins

Configure Jenkins Job (Git/ Assembla)

Schedule Jenkins job

Post Build Actions : Extended E-mail Notification

Web Hooks (Git/ Assembla)

Matrix-based Security

3. About Jenkins:
- Jenkins is an open source continuous integration (CI) tool written in Java.
Continuous integration (CI) is the practice, in software engineering, of merging all developer
working copies with a shared mainline several times a day. The main aim of CI is to prevent
integration problems
- Jenkins provides continuous integration services for software development. It is a server-
based system running in a servlet container such as Apache Tomcat.
- It supports SCM tools including AccuRev, CVS, Subversion, Git, Mercurial, Perforce,
Clearcase and RTC, and can execute Apache Ant and Apache Maven based projects as well as
arbitrary shell scripts and Windows batch commands.
- Builds can be started by various means, including being triggered by commit in a version
control system, scheduling via a cron-like mechanism, building when other builds have
completed, and by requesting a specific build URL.

4. Install Jenkins
- Download Jenkins.war file:
$ wget http://ftp-chi.osuosl.org/pub/jenkins/war/1.592/jenkins.war
- Run Jenkins:
$ java -jar jenkins.war
- By default, Jenkins listen on port 8080. Access this port with browser to start configuration
Command Line Parameters
- To change port numer:
$ java -jar jenkins.war --httpPort=$HTTP_PORT
- Binds Jenkins to the specific IP address (deafult is 0.0.0.0)
$ java -jar jenkins.war --httpListenAddress=$HTTP_HOST
- Runs Jenkins to include the $PREFIX at the end of the URL
$ java -jar jenkins.war --prefix=$PREFIX

5. Configure a Jenkins Job : Git and Assembla
- Under ‘Manage Jenkins’ -> ‘Manage Plugins’, select and install following plugins:
•
Github and Git plugins
•
Assembla and Assembla Auth Plugin
- Restart after finish the installation. After this is installed either create a new build or configure
an existing build job
- Add github repository path
-> In "Source Code Management" select "Git"
a) Provide Repository URL
b) Credentials of Repositories for private repository (login access/ SSH key)
c) Branch to build (i.e. branchName)

6. - Add a Build step to the Execute shell command. This gives the ability to define a bash script to
perform build execution
- Save changes and Run a build.
- Jenkins clone the project in its workspace and after that execute provided shell command
script

7. Schedule Jenkins Job
- Under “Configure” -> “Build trigger” give the time in cron syntax for triggering a job
automatically in Jenkins
Examples:
•
*/1 * * * * : Every minute
•
0 0 1 * * : Once in a day
•
0 0 * * 0 : Once in a week
•
0 0 * * * : Once in a day

8. Post Build Actions : Extended E-mail Notification
- Jenkins privides post build actions which executes after the jenkins build. Jenkins allows to
have email notification for successful or failed build.
- Install “Manage Jenkins” -> “Manage plugins” -> ”Email-ext plugin"
- Go to Manage Jenkins -> Configure System ->
a) In Jenkins Location provide "System Admin E-mail Address"
b) Extended E-mail Notification : Set up mail subject and contents settings

9. - In E-mail Notifications provide smtp mail server configuration
- Save the changes
- Go to Project Configuration -> Post Build Action -> Select "Editable E-mail Notifications"
- Provide email id of people in "Project recipients list", Attach Build Log (This document would
contain complete build report and would be attached with Email)
- In "Advanced Settings" option, Set "Triggers" to "Always". This would sent notifications for
every successful and failed build with complete logs.
- Save the changes

10. WebHook
A WebHook is an HTTP callback: an HTTP POST that occurs when something happens or a
simple event-notification via HTTP POST.
Build Jenkins Job on Git Commit
- With the latest Git plugin 1.1.14, can do this more easily by simply executing the following
command:
curl http://yourserver/jenkins/git/notifyCommit?url=<URL of the Git repository>
- This will scan all the jobs that’s configured to check out the specified URL, and if they are also
configured with polling, it’ll immediately trigger the polling (and if that finds a change worth a
build, a build will be triggered in turn.)
- Follow the follwoing steps to set-up:

Go to “Configure” -> “Build Trigger”

Check “Poll SCM” : Leave the schedule field empty

Now, go to “Settings” page of your github repository (http://github.com/
<user_id>/<project_name>/settings)

Search for “Jenkins (Git Plugin)” under “Webhooks & Services” -> “Services” -> “Add
services”

11. 
Provide Jenkins url. "Jenkins Url" is the base URL of Jenkins server

This willl hit /git/notifyCommit under github repository URL
- Add service and That's It
- Commit the changes. This will trigger jenkins job

12. WebHook with Assembla
- Add a Webhook tool via the Admin → Tools on the Assembla home screen (this action
requires to have admin rights)
- Create a new Webhook with the following options:
Title : ‘Jenkins Commit’ or any;
Authentication type: Basic;
External url: {IP address of your jenks server}/git/notifyCommit?url=%{repository_url};
Http metod: Get;
Content type – text/plain;
Leave the content field empty and tick ‘Code commits’ at ‘Post updates about’ section.

13. Matrix-based security
- Matrix-based security is one of the authorization strategies available for securing Jenkins.
- It allows to grant specific permissions to users and groups. Follow the following steps to
enable security:

Activate “Enable Security” under “Manage Jenkins” -> “Configure Global Security”

Select “Jenkins’ own user database” from “Security Realm” and activate jenkins sign up

14. 
Select “Matrix-based security” and set the permissions to user/ group
- Save changes