What is Jenkins
Jenkins is an open source continuous integration (CI) server. It manages and controls several stages of the software delivery process, including build, documentation, automated testing, packaging, and static code analysis. Jenkins is a highly popular DevOps tool used by thousands of development teams.
Jenkins automation is commonly triggered by code changes in repositories like GitHub, Bitbucket, and GitLab, and integrates with build tools like Maven and Gradle. Jenkins supports the use of container technologies like Docker and Kubernetes for testing and packaging of software releases, but it is neither a Kubernetes native solution nor a container-native CI solution. This is part of an extensive series of guides about CI/CD.
Jenkins Core Concepts
Jenkins Controller (Formerly Master)
The Jenkins architecture supports distributed builds. One Jenkins node functions as the organizer, called a Jenkins Controller. This node manages other nodes running the Jenkins Agent. It can also execute builds, although it isn’t as scalable as Jenkins agents.
The controller holds the central Jenkins configuration. It manages agents and their connections, loads plugins, and coordinates project flow.
Jenkins Agent (Formerly Slave)
The Jenkins Agent connects to the Jenkins Controller to run build jobs. To run it, you’ll need to install Java on a physical machine, virtual machine, cloud compute instance, Docker image, or Kubernetes cluster.
You can use multiple Jenkins Agents to balance build load, improve performance, and create a secure environment independent of the Controller.
A Jenkins node is an umbrella term for Agents and Controllers, regardless of their actual roles. A node is a machine on which you can build projects and pipelines. Jenkins automatically monitors the health of all connected nodes, and if metrics go below a threshold, it takes the node offline.
Jenkins Project (Formerly Job)
A Jenkins project or task is an automated process created by a Jenkins user. The plain Jenkins distribution offers a variety of build tasks that can support continuous integration workflows, and more are available through a large ecosystem of plugins.
Plugins are community-developed modules you can install on a Jenkins server. This adds features that Jenkins doesn’t have by default. You can install/upgrade all available plugins from the Jenkins dashboard.
A Jenkins Pipeline is a user-created pipeline model. The pipeline includes a variety of plugins that help you define step-by-step actions in your software pipeline. This includes:
- Automated builds.
- Multi-step testing.
- Deployment procedures.
- Security scanning
You can create pipelines directly in the user interface, or create a “Jenkinsfile” which represents a pipeline as code. Jenkinsfiles use a Groovy-compatible text-based format to define pipeline processes, and can be either declarative or scripted.
Jenkins elements interact and work together in the following way:
- Developers modify the source code, committing changes to the repository, and Jenkins creates a new build in order to handle the new Git commit.
- Jenkins can work in “push” or “pull” mode. The Jenkins CI server is either triggered by an event such as a code commit, or it can regularly check the repository for changes.
- The build server builds the code and generates an artifact. If the build fails, the developer receives an alert.
- Jenkins deploys the built application/executable to the test server, which can execute continuous, automated tests. Developers receive alerts if their changes impact functionality.
- Jenkins optionally deploys the changes to the production server if the code has no issues.
The following diagram illustrates the Jenkins architecture:
Image Source: Jenkins
You may need more than one Jenkins server to test code in different environments. A single server cannot always handle the load for large projects. If this is the case, you can use the distributed Jenkins architecture to implement continuous integration and testing. The Jenkins server can access the Controller environment, which distributes the workload across different Jenkins Agents.
This distributed model lets you run different builds and tests simultaneously, with each Jenkins Agent environment running a different version of the code and the Controller controlling the operations.
Jenkins Advantages and Disadvantages
Here are some of the key advantages of Jenkins:
- Highly extensible with a huge variety of existing plugins. Plugins contribute to Jenkins’ flexibility and rich scripting and declarative language which supports advanced, custom pipelines.
- Robust and reliable at almost any scale.
- Mature and battle-tested.
- Supports hybrid and multi-cloud environments.
- Offers an extensive knowledge base, documentation, and community resources.
- Based on Java, an enterprise development language with a broad ecosystem, making it suitable for legacy enterprise environments.
Here are some disadvantages of Jenkins:
- Single server architecture—uses a single server architecture, which limits resources to resources on a single computer, virtual machine, or container. Jenkins doesn’t allow server-to-server federation, which can cause performance issues in large-scale environments.
- Jenkins sprawl—this is a common problem which also stems from lack of federation. Multiple teams using Jenkins can create a large number of standalone Jenkins servers that are difficult to manage.
- Relies on dated Java architectures and technologies—specifically Servlet and Maven. In general, Jenkins uses a monolithic architecture and is not designed for newer Java technologies such as Spring Boot or GraalVM.
- Not container native—Jenkins was designed in an era before containers and Kubernetes gained popularity, and while it supports container technology, it does not have nuanced support for container and orchestration mechanisms.
- Difficult to implement in production environments—developing continuous delivery pipelines with Jenkinsfiles requires coding in a declarative or scripting language, and complex pipelines can be difficult to code, debug, and maintain.
- Offers no functionality for real production deployments—“deploying with Jenkins” means running a fully customized set of scripts to handle the deployment.
- Jenkins itself requires deployment—this can be difficult to automate. Organizations that need to combine Jenkins with a continuous delivery solution have traditionally used configuration management to do this, but this adds another layer of complexity and is error-prone.
- Complicated plugin management—Jenkins has nearly 2,000 plugins, which can be overwhelming to sort through until you find a useful plugin. Many plugins also have dependencies that increase the management burden, while some plugins may conflict with each other. There is no guarantee a plugin you use will continue to be maintained.
- Groovy expertise requirements—Jenkins has programmatic pipelines implemented in Groovy, a language that is currently not in wide use and can make scripts difficult to work with. Jenkins supports scripted and declarative Groovy modes.
For these reasons, many teams are transitioning away from Jenkins and adopting newer solutions that are more supportive of a containerized, microservices-oriented DevOps environment.
What Is Jenkins X?
Jenkins X is a CI/CD solution that continuously ships applications with Kubernetes. Jenkins X emphasizes CI/CD automation for the cloud.
Jenkins X combines Jenkins with open source tools like Helm, Docker, Nexus, and KSync. It automatically installs, configures, and upgrades these tools to integrate them into your CI/CD process.
Jenkins X offers feedback for all pull requests, providing previews before pushing code changes to the staging and production environments. It helps you incorporate authentication and reliability early on, preventing post-deployment surprises. You leverage a higher degree of automation to enable frequent, secure, and predictable software releases.
Jenkins X is useful regardless of your familiarity with Kubernetes, providing a CI/CD process to facilitate cloud migration. It supports bootstrapping onto your chosen cloud, which is crucial for a hybrid setup.
However, Jenkins X also has the following drawbacks:
- A primary drawback of Jenkins X is that the project went through rapid change, which makes it difficult to adopt by new users and challenging to maintain for existing users.
- It only deploys via Helm, so you need to adopt Helm if you haven’t.
- It requires trunk-based development.
- It lacks its own UI (it relies on the limited Jenkins UI), so you need to use the command line for new constructs.
- Scales by adding builders to its Kubernetes cluster and automatically connecting Jenkins Slaves to the Master.
- You can implement a serverless installation without a Master, which consumes excessive resources.
Codefresh: A Modern Alternative to Jenkins
You can’t get to continuous delivery or deployment without first solving continuous integration. Codefresh automatically creates a Delivery Pipeline, which is a workflow along with the events that trigger it. We’ve added a pipeline creation wizard that will create all the component configurations so you can spend less time with YAML and more time getting work done.
At the end of the pipeline creation wizard, Codefresh commits the configuration to git and allows its built-in Argo CD instance to deploy them to Kubernetes.
The Delivery pipeline model also allows the creation of a single reusable pipeline that lets DevOps teams build once and use everywhere. Each step in a workflow operates in its own container and pod. This allows pipelines to take advantage of the distributed architecture of Kubernetes to easily scale both on the number of running workflows and within each workflow itself.
Teams that adopt Codefresh deploy more often, with greater confidence, and are able to resolve issues in production much more quickly. This is because we unlock the full potential of Argo to create a single cohesive software supply chain. For users of traditional CI/CD tooling, the fresh approach to software delivery is dramatically easier to adopt, more scalable, and much easier to manage with the unique hybrid model.
See Our Additional Guides on Key CI/CD Topics
Together with our content partners, we have authored in-depth guides on several other topics that can also be useful as you explore the world of CI/CD.
- DevOps Toolchain: 11 Types of Tools You Can’t Do Without
- Why You Need DevOps Testing Tools and 5 Tools You Should Know
- GitHub Actions Tutorial and Examples
- GitHub Actions Workflows: Basics, Examples, and a Quick Tutorial
- Harness vs. Jenkins: DevOps Tool Comparison
- Jenkins X: How It Works and Creating Your First Project
- Jenkins Pipeline: Examples, Usage, and Best Practices
- What is Blue/Green Deployment?
- What Are Canary Deployments?
- AWS Blue/Green Deployment with Fargate, EKS, and Elastic Beanstalk
Conquer DevOps with Codefresh
Realize your true DevOps potential with the premier GitOps solution powered by Argo.
Check It Out
What is Jenkins and its architecture? ›
The Jenkins CI server checks the repository at regular intervals and pulls any newly available code. The Build Server builds the code into an executable file. In case the build fails, feedback is sent to the developers. Jenkins deploys the build application to the test server.
- Pipeline. A Pipeline is a user-defined model of a CD pipeline. ...
- Node. A node is a machine which is part of the Jenkins environment and is capable of executing a Pipeline. ...
- Stage. ...
Jenkins is an open-source free automation tool used to build and test software projects. The tool makes it painless for developers to integrate changes to the project. Jenkins' primary focus is to keep track of the version control system and initiate and monitor a build system if there are any changes.What is Jenkins explained simply? ›
Jenkins is an open-source automation tool written in Java with plugins built for continuous integration. Jenkins is used to build and test your software projects continuously making it easier for developers to integrate changes to the project, and making it easier for users to obtain a fresh build.What architecture is recommended by the Jenkins? ›
Jenkins uses a Master-Slave architecture to manage distributed builds. In this architecture, Master and Slave communicate through TCP/IP protocol.What are Jenkins components? ›
Following are the key components in Jenkins. Jenkins Master Node. Jenkins Agent Nodes/Clouds. Jenkins Web Interface.How many types of builds in Jenkins? ›
Jenkins supports several different types of build jobs. The two most commonly-used are the freestyle builds and the Maven 2/3 builds. The freestyle projects allow you to configure just about any sort of build job: they are highly flexible and very configurable.What are the 2 types of Jenkins pipeline? ›
Different Types of Jenkins CI/CD Pipelines. Scripted Pipeline. Declarative Pipeline.What are the 2 types of pipelines available in Jenkins? ›
Jenkins provides two different syntaxes for pipelines. When DevOps engineers write a Jenkins pipeline, they can choose between declarative and scripted.What are the three blocks in the Jenkins pipeline? ›
Stage block descriptions are displayed in the Jenkins UI. Here we are defining three stages – Build , Test , and Deploy . Each of them can contain specific scripted code that performs the required operations.
What is the main benefit of using Jenkins? ›
Jenkins is used today along the entire software development lifecycle, enabling the integration and automation of different processes, including building, testing, and deployment. Jenkins creates 'pipelines', which define the series of steps that the server will take to perform the required tasks.What are the advantages of Jenkins *? ›
Advantages of Jenkins are as follows:
Notifies the developers about build report status using LDAP (Lightweight Directory Access Protocol) mail server. Maven release project is automated with simple steps. Easy bug tracking. Automatic changes get updated in the build report with notification.
- Jenkins Error: Running two Java Versions – Jenkins Problem in Mac OS.
- Jenkins Error: /usr/bin/p4 error in windows machine with jenkins.
- Jenkins Error: Jenkins time-out while pushing to github.
- Jenkins Error: Jenkins Workspace Issue.
The following commands when appended to the Jenkins instance URL will carry out the relevant actions on the Jenkins instance. http://localhost:8080/jenkins/exit − shutdown jenkins. http://localhost:8080/jenkins/restart − restart jenkins. http://localhost:8080/jenkins/reload − to reload the configuration.How do you explain Jenkins pipeline? ›
Jenkins Pipeline (or simply "Pipeline") is a suite of plugins which supports implementing and integrating continuous delivery pipelines into Jenkins. A continuous delivery pipeline is an automated expression of your process for getting software from version control right through to your users and customers.Which are Jenkins job types? ›
- Freestyle Project.
- Maven Project.
- Multi-configuration Project.
- GitHub Organization.
Jenkins is an open-source automation tool for Continuous Integration (CI) and Continuous Deployment (CD). It is a server-based system that runs in servlet containers like Apache Tomcat.What is the difference between Jenkins and Jenkins? ›
Jenkins vs. Jenkins X.
|Jenkins is unopinionated and more flexible.||Jenkins X takes an opinionated approach to follow best practices.|
- Install Java Development Kit (JDK) ...
- Set the Path for the Environmental Variable for JDK. ...
- Download and Install Jenkins. ...
- Run Jenkins on Localhost 8080. ...
- Jenkins Server Interface. ...
- Build and Run a Job on Jenkins.
Use the Jenkins global database
So the easiest way for plugins to start storing data to the database is to use this Database instance. This global database instance is kept in the GlobalDatabaseConfiguration class. You can inject this via @Inject , or you can call GlobalDatabaseConfiguration.
What architecture is recommended for a scalable Jenkins environment? ›
Which architecture is recommended for a scalable Jenkins environment? Distributed builds architecture is prescribed for a scalable Jenkins environment because the agents perform the main work and the master maintains the coordination.What are the build tools in Jenkins? ›
Jenkins can use Maven as its build tool.What are the main plugins in Jenkins? ›
- Git Plugin. Git is one of the most installed Jenkins add-ons available on its repository. ...
- Kubernetes Plugin. Kubernetes is another widely used plugin in Jenkins. ...
- Jira Plugin. ...
- Docker Plugin. ...
- Maven Integration Plugin. ...
- Blue Ocean Plugin. ...
- Amazon EC2 Plugin. ...
- Pipeline Plugin.
- Software build using build systems such as Gradle, Maven, and more.
- Automation testing using test frameworks such as Nose2, PyTest, Robot, Selenium, and more.
- Execute test scripts (using Windows terminal, Linux shell, etc.
It contains a collection of states such as build, deploy, test and release. These jobs or events are interlinked with each other. Every state has its jobs, which work in a sequence called a continuous delivery pipeline.How many jobs we can run in Jenkins? ›
These equations assume that the Jenkins controller will have 5 cores with one core per 100 jobs (500 total jobs/controller) and that teams will be divided into groups of 40.What is the difference between Jenkins and Jenkins pipeline? ›
1 Answer. The major difference between any Jenkins job and a Jenkins Pipeline Job is that the Pipeline Scripted job runs on the Jenkins master. This uses a lightweight executor which uses only some resources to translate in the master to atomic commands that execute or send to the agents.What is difference between Jenkins pipeline and Jenkins job? ›
The main difference between any job and a Pipeline Job is that the Pipeline Scripted job runs on the Jenkins controller, using a lightweight executor expected to use very few resources in order to translate the pipeline to atomic commands that execute or send to the agents.What are the three basic types of pipelines system? ›
There are essentially three major types of pipelines along the transportation route: gathering systems, transmission systems, and distribution systems.What language is used in Jenkins pipeline? ›
Pipelines are Jenkins jobs enabled by the Pipeline (formerly called “workflow”) plugin and built with simple text scripts that use a Pipeline DSL (domain-specific language) based on the Groovy programming language.
How many pipelines can be created in Jenkins? ›
There are two types of pipelines in Jenkins: Declarative. Scripted.In which language is Jenkins file written? ›
Jenkins is an open source continuous integration/continuous delivery and deployment (CI/CD) automation software DevOps tool written in the Java programming language. It is used to implement CI/CD workflows, called pipelines.Where are scripts stored in Jenkins? ›
The scripts are managed by the Config File Provider Plugin, go to the "Manage Jenkins" screen and click on the "Managed files" item. After installing the "Managed Scripts" plugin, you have a new option to create a managed script in the type list.What are the two types of pipeline in DevOps? ›
Continuous Integration and Continuous Delivery: These two components are typically mentioned together, usually referred to as CI/CD or a CI/CD pipeline.What is the difference between node and agent in Jenkins? ›
Node: A Pipeline performs most of the work in the context of one or more declared node steps. Agent: The agent directive specifies where the entire Pipeline, or a specific stage, will execute in the Jenkins environment depending on where the agent directive is placed.What command is used to start Jenkins? ›
Run the command java -jar jenkins.war. Browse to http://localhost:8080 and wait until the Unlock Jenkins page appears.Why do we need pipelines in Jenkins? ›
Jenkins Pipeline (or simply Pipeline with a capital P) is a suite of plugins that supports implementing and integrating continuous delivery pipelines into Jenkins. This allows you to automate the process of getting software from version control through to your users and customers.Why Jenkins is better than others? ›
Jenkins doesn't offer a built-in CI feature, but it provides an easy way to set up continuous integration and continuous deployment for various code repositories and languages using pipelines. It allows you to integrate the entire development technology stack to deliver products faster and better.What is purpose of Jenkins in testing? ›
Jenkins is a popular CI orchestration tool. It provides numerous plugins for integration with multiple test automation tools and frameworks into the test pipeline. When it comes to Test Automation, Jenkins provides plugins that help run test suites, gather dashboard results, and provide details on failures.Which tool is better than Jenkins? ›
Every GitLab user has access to the built-in CI/CD tool GitLab CI. GitLab CI offers an excellent UI which makes it easy to implement CI/CD without employing another third-party tool like Jenkins. This tool is cloud-based and highly scalable.
Can we use Jenkins without Docker? ›
I know that jenkins can be installed without a docker at all (“Installing Jenkins - Linux”). I also assume that I can use the jenkins/jenkins container by itself (implied by this section).What is the disadvantage of Jenkins? ›
Here are some disadvantages of Jenkins: Single server architecture—uses a single server architecture, which limits resources to resources on a single computer, virtual machine, or container. Jenkins doesn't allow server-to-server federation, which can cause performance issues in large-scale environments.What are the two main things in the Jenkins architecture? ›
Here's how Jenkins elements are put together and interact: Developers commit changes to the source code, found in the repository. The Jenkins CI server checks the repository at regular intervals and pulls any newly available code. The Build Server builds the code into an executable file.
- Gross Errors.
- Random Errors.
- Systematic Errors.
- Jenkins Master/Server.
- Jenkins Slave/Node/Build Server.
It contains a group of states called build, deploy, test and release. These events are interlinked with each other. Every state has its events, which work in a sequence called a continuous delivery pipeline.What are tools in Jenkins? ›
- Eclipse Jenkins Editor.
- VisualStudio Code Jenkins Pipeline Linter Connector.
- Neovim nvim-jenkinsfile-linter plugin.
- Atom linter-jenkins package.
- Sublime Text Jenkinsfile package.
What's a Jenkins Multibranch Pipeline? A multibranch job is simply a folder of pipeline jobs. For every branch you have, Jenkins will create a folder. So instead of creating a pipeline job for each of the branches you have in a git repository, you could use a multibranch job.What are pipelines in Jenkins? ›
Jenkins Pipeline (or simply "Pipeline") is a suite of plugins which supports implementing and integrating continuous delivery pipelines into Jenkins. A continuous delivery pipeline is an automated expression of your process for getting software from version control right through to your users and customers.What are the different types of projects in Jenkins? ›
- Freestyle project.
- Maven project.
- Multibranch pipeline.
- External Job.
- Multi-configuration project.
- Github organization.
How do you explain CI CD pipeline in Jenkins? ›
Create a Pipeline Job
Select and define what Jenkins job that is to be created. Select Pipeline, give it a name and click OK. Scroll down and find the pipeline section. Either directly write a pipeline script or retrieve the Jenkins file from SCM (Source Code Management).
In the normal distribution, there are two parameters that can characterize a distribution - the mean and standard deviation. By varying these two parameters, you can get different kinds of normal distributions.What are the 2 types of function parameters? ›
Formal parameters and actual parameters
Essentially, the variables being passed in the function call are actual parameters, and the variables being initialized and used in the function are formal* *parameters.
A key parameter is the gate depletion width, Wd, within which the mobile carriers (holes in the case of nMOSFETs) are swept away by the applied gate field. From: Encyclopedia of Materials: Science and Technology, 2001.