Introduction to Continuous Integration Jenkins
In today’s article, let us go in-depth through the concepts of Continuous Integration with Jenkins. Once we discuss the benefits and best practices of using Continuous Integration with Jenkins, let us proceed further with the concepts of Continuous Deployment and Continuous Delivery and conclude with the differences between these three.
What is Jenkins
Jenkins is a powerful application that allows continuous integration and continuous delivery of projects, regardless of the platform you are working on. It is an open-source automation server which is written in Java and finds its use in automating the non-human part of the software development process with continuous integration and encourages technical aspects of continuous delivery.
With Jenkins, organizations can accelerate the software development process by automating the build and testing at a rapid rate. With more than four hundred thousand installations and increasing every day, Jenkins is a widely used application around the world. One of the key advantages of Jenkins is that it requires little maintenance and has a built-in GUI tool for easy updates.
Jenkins also provides a customized solution as there are over 400 plugins to support building and testing virtually any project. The Jenkins project is an independent open source community under the umbrella of a non-profit organization Software in the Public Interest, which owns the key project assets including the Jenkins trademark. The project has its own decision-making process and governance board. It manages and controls the complete software delivery processes throughout the entire lifecycle, building, testing, documenting the software, deploying and other stages of a software development life cycle.
In Continuous Integration after a code commit, the software is built and tested immediately. But when we consider a large project with many developers, commits are made many times during a day and with each commit, code is built and tested. Continuous integration is a process in which all development work is integrated as early as possible.
The resulting artifacts are automatically created and tested. This process allows for identifying errors as early as possible. If the test is passed, build is tested for deployment. If the deployment is a success, the code is pushed to production. This commit, build, test, and deploy is a continuous process and hence the name continuous integration/deployment.
Let us consider a scenario where the complete source code of the application was built and then deployed on the test server for testing and then we can compare with Continuous Integration approach with Jenkins. Upon careful consideration, we can come to the conclusion that this process has many flaws. Let us go through them one by one
- Developers have to wait until the complete software is developed for the test results.
- There is a high probability that the test results might show multiple bugs. This will make it tough for developers to locate those bugs because they have to check the entire source code of the application.
- The entire software delivery process is slowed.
- Continuous feedback pertaining to things like coding or architectural issues, build failures, test status and file release uploads will be missing due to which the quality of software can go down.
- The whole process is manual which increases the risk of frequent failure.
It is evident from the above-stated problems that not only the software delivery process becomes slow but the quality of software also goes down. This leads to customer dissatisfaction.
So to overcome such chaos there was a dire need for a system to exist where developers can continuously trigger a build and test for every change made in the source code. This is what CI is all about. Jenkins is the most mature CI tool available so let us see how Continuous Integration with Jenkins overcame the above shortcomings.
The basic functionality of Jenkins is to execute a predefined list of steps, for example, to compile Java source code and build a JAR from the resulting classes. The trigger for this execution can be time or event-based say every 15 minutes or after every new commit.
Let us consider a scenario for the same.
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When a developer commits the code to the source code repository, the Jenkins server is already checking the repository at regular intervals for changes. Soon after the commit occurs, the Jenkins server detects the changes that have occurred in the source code repository. Now, the Jenkins server will pull those changes and will start preparing a new build. In case the build fails, the concerned team will be notified. And if the build is successful, then the build is deployed in the test server.
Jenkins can be customized according to the requirements for continuous integrations. Jenkins Pipeline is a suite of plugins which supports implementing and integrating continuous delivery pipelines into Jenkins. Pipeline adds a powerful set of automation tools onto Jenkins. The pipeline can be configured for creating the build with the following steps: Prepare, test, package, publish, deploy.
Setting up a Pipeline project means writing a script that will sequentially apply some steps of the process we want to accomplish. After running it, Jenkins generates feedback, if these constraints are good to go, the artifact is valid. And then the developers are notified about the build and test results. Jenkins will continue to check the source code repository for further changes made in the source code, and the whole process will keep repeating.
Benefits of Continuous Integration
- Spot any integration challenges right away. The small change sets help in easy detection of Integrations bugs.
- Increase Your Code Coverage with less number of changes
- Build Stuff Faster and never ship broken code
- Consistency of Build Process
- Increases confidence in the software. Metrics generated from automated testing and CI (such as metrics for code coverage, code complexity, and features complete) focus developers on developing functional, quality code, and help develop momentum in a team.
A continuous deployment is an approach to releasing software on production servers continuously in an automated fashion. Continuous deployment can be thought of as an extension of continuous integration, aiming at minimizing lead time, the time elapsed between development writing one new line of code and this new code being used by live users, in production.
It is the process of automating the code delivery tasks from development to production environment consisting of version control management, deployment on each environment followed by automated testing and taking decisions based on the results of the previous step.
So, once code passes through all the stages of compiling the source code, validating the source code, reviewing the code, performing unit and integration testing, and packaging the application continuously, it will then be deployed onto the test servers to perform user acceptance tests. Once that is done, the software will be deployed onto the production servers for release. This is said to be continuous deployment. If you can set up a project server once, you can set up Jenkins to deploy that project again and again as you develop, maintain, and expand it
Benefits of Continuous Deployment
The Do-It-Yourself need for Continuous Delivery is eliminated and thereby increasing the focus on the product.
- Ship both cloud-native and traditional applications in a unified pipeline.
- There is a shift of focus onto actual testing as the repetitive tasks are automated.
- Create workflows across the development, testing, and production environments.
- Fault isolation is simpler and quicker.
These are only some of the simple advantages of Continuous Deployment that organizations powered by software can be able to enjoy by adapting themselves to this practice.
Continuous delivery (CD) is a software release approach in which development teams produce and test code in short cycles, usually with a high degree of automation. The goal of Continuous Delivery is to keep software release-ready and enable a repeatable, reliable way to deploy software to any environment. It aims to make feedback loops as short as possible to improve software quality
Continuous Delivery takes Agile to its logical conclusion. It is an extension of continuous integration to make sure that you can release new changes to your customers quickly in a sustainable way. Continuous Delivery involves all dimensions of your R&D and Operations organizations – consisting of Team Collaboration, Agile and DevOps practices, Continuous Integration (CI), Build Automation, Test Automation, Deployment Automation and Shared Visibility.
With continuous delivery, you can decide to release daily, weekly, fortnightly, or whatever suits your business requirements. It becomes easy to continuously adapt software in line with user feedback, market shifts and business strategy changes through low-risk and reliable releases. This helps developers more thoroughly validate updates and preemptively discover issues.
Continuous Delivery and Continuous Deployment
Continuous Delivery contrasts with continuous deployment. Here the software is also produced in short cycles but through automated deployments rather than manual ones. Continuous Delivery does not involve deployment to production on every change that occurs. You just need to ensure that the code is always in a deployable state, so you can deploy it easily whenever you want.
On the other hand, Continuous Deployment requires every change to be deployed automatically, without human intervention. Once Continuous Integration stages are completed, the newly built application is automatically deployed to production then it is Continuous Deployment. But it is Continuous Delivery if we manage to automate everything, but decide to require human approval in order to proceed with the deployment of the new version.
Though the difference is very much subtle, it has enormous implications, making each technique appropriate for various situations.
Benefits of Continuous Delivery
- Velocity: CD facilitates and encourages shorter delivery cycles. Velocity means responsible speed and not suicidal speed. Automated software delivery pipelines help organizations respond to market changes better.
- Faster Feedback and Lean
- Productivity: Productivity increases when tedious and repetitive tasks, like filling out a bug report for every defect discovered, can be performed by pipelines instead of humans.
- Minimize Risk.
- Sustainability: CD provides the business with more flexibility in how it delivers features and fixes. Specific sets of features can be released to specific customers or released to a subset of customers, to ensure they function and scale as designed.
Continuous Integration vs Continuous Delivery vs Continuous Deployment
Continuous Integration is merging all code from all developers to one central branch of the repo many times a day trying to avoid conflicts in the code in the future. Continuous integration can be considered a part of both continuous delivery and continuous deployment. And continuous deployment is like continuous delivery, except that releases happen automatically.
Continuous Delivery is a small build cycle with short sprints where the aim is to keep the code in a deployable state at any given time. With Continuous Deployment, every change that is made is automatically deployed to production. This approach works well in enterprise environments where you plan to use the user as the actual tester and it can be quicker to release.
Development teams can take advantage of Continuous Integration by deploying a solution such as Jenkins, the most popular open-source tool in the space, and configuring it to build and test their code. Continuous Delivery usually involves other DevOps-related tools like Puppet, Chef, Ansible, or SaltStack to install and configure environments for testing.
Docker and container orchestration components like Kubernetes make it easier for teams to automatically set up and tear down these environments as part of the CI/CD process. The open-source project Spinnaker, created by Netflix, provides a robust Continuous Delivery and Continuous Deployment solution.
Although Continuous Deployment works best for websites and APIs, Continuous Integration and Continuous Delivery help with all software development, including shrink-wrapped products and internal use only applications.
We can discuss and compare the benefits provided by each of the approaches
Shipping of less number of bugs to production due to early capture of regressions by the automated tests.
Less pressure on decisions for small changes thereby faster iterations.
Faster development time as the need for a pause between releases is less. For every change, deployments pipelines are triggered automatically
Ease of building the release due to early resolving of integration issues.
Acceleration of feedback loop for customers by releasing more often.
Less risky releases and they are also easier to fix since the changes are in the form of small batches.
Minimizing context switching for developers as they are alerted soon after any build breaks.
Reduction in complexity of software deployment.
The continuous stream of improvements and quality increases every day, instead of every month, quarter or year.
Cost of testing is reduced drastically.
Less time spent on testing and more focus on improvements to the quality culture.
We hope you have got a clear understanding of the various terms like Continuous Integrations, Continuous Delivery and Deployment and also their respective benefits. We encourage you to make use of these concepts for a better overall project experience.