Python

Using Python with Jenkins

In this article, we will explain how to use Python with Jenkins. We will look at the following aspects:

  • What Jenkins is?
  • Jenkins API in Python
  • Install Python Package
  • Create a Jenkins client

You can also check this tutorial in the following video:

Jenkings Tutorial For Beginners – Video

1. What is Jenkins?

python jenkins

Jenkins is a CI/CD tool developed in Java. It was developed in 2004 by a Sun systems developer named Kohsuke Kawaguchi. His goal was to create a method to perform continuous integration. The idea was to test the code before committing to avoid breaking builds. Although Jenkins started as a continuous integration tool, the current use covers the whole software delivery pipeline, including deployment. Jenkins encompasses various DevOps terminology throughout different pipeline creation and management options. Below is a list of some of the common terms and what they mean.

1.1 Jenkins Pipeline

The Jenkins Pipeline is a user-made model for the continuous delivery pipeline. All the software is subjected to a 3-step process

  • Automated Builds
  • Automated Testing
  • Automated Deployment

In Jenkins, there are two ways to create a pipeline:

  1. Define the Pipeline through the user interface directly.  
  2. Use the Pipeline as Code methodology and create a Jenkinsfile. The text file uses Groovy-compatible syntax to define the pipeline process.
pipeline {
    agent any
    stages {
        stage('Build') {
            steps {
                echo 'Building…'
            }
        }
        stage('Integ Test') {
            steps {
                echo 'Testing…'
            }
        }
        stage('Deploy') {
            steps {
                echo 'Deploying...'
            }
        }
    }
}
  • The mandatory pipeline { } block invokes the Jenkins Pipeline plugin.
  • The keyword agent defines where the Pipeline runs, where any indicates the Pipeline runs on any available agent.
  • The stages { } block represents the sequence in which the Pipeline runs.
  • The code contains three stages: BuildTest and Deploy, each with its respective steps { }.
  • The steps { } tell Jenkins what to do at a particular point.

The scripted equivalent of the Jenkinsfile looks like the following:

node {  
    stage('Build') { 
        echo 'Building…'
    }
    stage('Integ Test') { 
        echo 'Testing…'
    }
    stage('Deploy') { 
        echo 'Deploying…'
    }
}

Checking a Jenkinsfile into a source control tool such as git allows the whole team to edit, review, and adapt the steps in the delivery pipeline.

1.2 Continuous integration

Continuous integration is a software development procedure where each applied change invokes an automated build test. The process ensures the code integrates into a working executable form without bugs.

Continuous integration is a critical aspect in environments with multiple developers. Each developer makes changes to code, and each change has potential issues.

A continuous integration tool such as Jenkins helps test, identify, and address problems before applying changes to production.

1.3 Automated Testing

Automated testing for Jenkins presets test execution and stores the results. The idea is to ensure code works in various scenarios. Creating automated tests for distinct environments, such as several Java versions or operating systems, helps foresee and prevent problems in later releases.

The automated testing phases embed into the CI pipeline in Jenkins seamlessly. Various plugins help run unit, integration, functional, and regression tests and store the results for later viewing and analysis

2. Jenkins API in Python

For the purpose of this discussion, we will be using the Python Jenkins library. This is a python wrapper for the Jenkins REST API. It provides a higher-level API containing a number of convenience functions.

Python-Jenkins can be used to automate the deployed Jenkins servers. Some of the things we can use it for:

  • Create new jobs
  • Copy existing jobs
  • Delete jobs
  • Update jobs
  • Get a job’s build information
  • Get Jenkins master version information
  • Get Jenkins plugin information
  • Start a build on a job
  • Create nodes
  • Enable/Disable nodes
  • Get information on nodes
  • Put server in shutdown mode (quiet down)
  • List running builds
  • Delete builds etc

2.1 Installation of Python-Jenkins

sudo pip install python-jenkins

The above command installs the library on your machine. Alternatively, you can use PyCharm IDE for the installation too.

3. Create Jenkins Client

The below code snippet shows how to connect to Jenkins and get the server version

import jenkins
server = jenkins.Jenkins('http://jenkins-hostname:port', username='user_id', password='password')
user = server.get_whoami()
version = server.get_version()
print('Hi %s, Welcome to Jenkins version %s' % (user['fullName'], version))

Line 1 above imports the Jenkins module/package which gives us access to the Jenkins API

Line 2 above connects to the Jenkins server running on some server say localhost and port say 8080 and provides the username and password

Line 3 captures the name of the user running the code

Line 4 gets the server version

Line 5 prints the user name and the server version

4. Get All Jenkins Jobs

We can use the python package’s inbuilt method to access all configured Jenkins jobs. The following code is used to retrieve all of the jobs that are configured on your CI system

import jenkins
jenkins_client = jenkins.Jenkins('http://jenkins-hostname:port/', username='user', password='password')
jobs = jenkins_client.get_all_jobs(folder_depth=None)
for job in jobs:
    print(job['fullname'])

Line 1 above imports the Jenkins module/package which gives us access to the Jenkins API

Line 2 above connects to the Jenkins server running on some server say localhost and port say 8080 and provides the username and password

Line 3 captures all the jobs running on the server (just the top-level names) in a python iterable

Line 4 and 5 loops through the list of jobs and print them to the console

5. Summary

In this article, we tried to understand what Jenkins is, what is used for and the various important terms related to CI/CD process.

We also learned how to install the Python Jenkins library and use the Jenkins API to talk to the Jenkins server hosted on some server, e.g localhost.

More details about the Python Jenkins library can be found here.

Nitin Kulkarni

Nitin is an experienced IT professional with over 20 years of experience across the globe. He has lead and delivered many complex projects involving Cloud Computing, API design, DevOps and Microservices. He has a solid history of aligning systems with business strategy with a comprehensive knowledge of systems architecture principles, software development languages, software, and infrastructure. He is a certified AWS and TOGAF Architect. He holds a bachelor's degree from the University of Pune, India, and currently pursuing his Master's degree in Georgia Tech.
Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
Back to top button