What is Docker
- Docker takes away repetitive, mundane configuration tasks and is used throughout the development lifecycle for fast, easy and portable application development - desktop and cloud. Docker’s comprehensive end to end platform includes UIs, CLIs, APIs and security that are engineered to work together across the entire application delivery lifecycle.
- Its one of the best vertualization platform to containerise your app.
- A huge benefit of this is the ability seperate non-dependent steps and run them in parallel, running application in containers instead of virtual machines.
- Make it easier to create, deploy and run application by using containers.
Continuce Integration CI and Continuce Delivery and Deployment CD
- It's a backbone of DevOps practices and automation.
- Jenkins offers a simple way to set up a continuous integration or continuous delivery (CI/CD) environment for almost any combination of languages and source code repositories using pipelines, as well as automating other routine development tasks.
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.
Pipelines leverage the power of multiple steps to execute both simple and complex tasks according to parameters that you establish. Once created, pipelines can build code and orchestrate the work required to drive applications from commit to delivery.
- Step 1 — How to create a Jenkins job —
- Step 2 — How to build a pipeline in Jenkins
- Step 3 — How to link the jobs
Prerequisites: Jenkins and Docker should be installed on your system
Jenkins: https://jenkins.io/doc/book/installing/
Docker: https://docs.docker.com/search/?q=install
Step 1: Start Jenkins Run this command from the folder where you have jenkins.war file Command to start Jenkins: java -jar jenkins.war Open your browser and type www.localhost:8080 If port 8080 is already in use then use java -jar jenkins.war –-httpPort=7070 (you can specify any other port number). Login to your account:
Click on New Item
Enter name as Job1 (you can choose any name you wish)
select freestyle project then click OK Repeat these steps to create to 2 more jobs with names Job2 and Job3
click on dashboard Your dashboard should look like this
Now click on Job1 Click on Configure on the left menu
click on add build step
Select Execute shell
Enter this command: date
Then click on Post-build Actions and select build other projects
Enter name of Job2 then click apply and save.
Click on back to dashboard and repeat same steps as Job1:
click on Job2 then click on configure
click on add build step and select Execute shell
Enter this command: sudo docker pull yourname/jenkins:v1
Enter Job3 in Project to build field, apply and save.
Click on Back to dashboard
click on Job3 then click on Configure
click on Add build step and select Execute shell
Enter this command: sudo docker run yourname/jenkins:v1
Click apply and save.
We have built our pipeline using Jenkins!!! Its show time now!
Back to dashboard and click on Job1
Click on Build Now on the left menu above
It will build the Job1 simply by printing today’s date and trigger the next Job — Job2
To see the outcome of Job1 click on console output
Job1 has been successfully completed and it automatically triggered Job2
Click on Job2 on the above screen on your system then click on down arrow underneath build history and select Console output
Job2 output will pull the image from Docker hub repository as below
Job2 has successfully pulled Docker image from Docker hub repository!
Click on Job3 on the above screen on your system and repeat same steps as Job2 to view Console output for Job3
Job3 will run the image pulled by Job2 and display the message from Docker image as below