Automation Using the Dockerfile, Github & Jenkins
What is Dockerfile:
Docker can build images automatically by reading the instructions from a Dockerfile. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build users can create an automated build that executes several command-line instructions in succession.
Objective:
1. Create container image that’s has Jenkins installed using dockerfile
2. When we launch this image, it should automatically starts Jenkins service in the container.
3. Create a job chain of job1, job2, job3 and job4 using build pipeline plugin in Jenkins
4. Job1 : Pull the Github repo automatically when some developers push repo to Github.
5. Job2 : By looking at the code or program file, Jenkins should automatically start the respective language interpreter install image container to deploy code ( eg. If code is of HTML, then Jenkins should start the container that has HTML already installed ).
6. Job3 : Test your app if it is working or not.
7. Job4 : if app is not working , then send email to developer with error messages.
8. Create One extra job job5 for monitor : If container where app is running. fails due to any reson then this job should automatically start the container again.
Prerequisite:
- RHEL/ Centos virtual machine.
- Docker installed in the system.
Solution:
Step1: We need to create a image that contains jenkins inside it using the dockerfile.
In this dockerfile we have installed the jenkins with root power inside the centos os.
We need to build this image using the command:
#docker build -t <image name>:<version name> <dockerfile location>
Step2: We launch the container that has automatically jenkins installed in it.
In this we exposed the jenkins service to the port 1529. Here we need to configure the jenkins.
Step3: After logging into this we need to install the github plugin & need to create the job pipeline.
Job1 : The main work of job1 is to pull the Github repo (code) automatically when some developers push repo (code) to Github. Also we use Poll SCM to check the commit in github repo on per minute basis.
Step4: It is the most critical part of the project.
Job2: This job is so intelligent that it will automatically detects the language of the webapp & launch the the respective server container. For this we have created the html image using the dockerfile concept & for php used the image from the docker hub.
Here we have used the concept of mounting the volume with the document root folder.
Step5: Job3: This job will run our code on the machine & see whether it is working properly or not. If not working properly it will automatically fails itself & trigger the job4.
For testing purpose we use the environmental variable.
Step6: Job4: This job is basically a notifier job which will share the status of the website with the developer by sending the mail. For sending the mail I have used python script.
I will share my github repo link for the reference.
Step7: Job5: Till here we have build the automated infrastructure but what if the running container fails due to any reason. For this we need to create one more job that will monitor the container & if failed then launches it again. But if it launches a new one then we will lose the previous data, to overcome this problem we have used the volume mount option while launching the container.
Outputs:
Output of job1:
Output of job2:
Output job3:
Output job4:
Output of job5:
Pipeline View:
Github URL:
https://github.com/prashant1529/devtask2
Thank You!