Github-Jenkins-Docker

• Create container image that has Jenkins installed using dockerfile, when we launch this image, it should automatically start Jenkins service in the container.

• Create a job chain of job1, job2, job3 and job4 using build pipeline plugin in Jenkins

• Job1 : Pull the Github repo automatically when some developers push repo to Github.

• 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 PHP, then Jenkins should start the container that has PHP already installed ).

• Job3 : Test your app if it is working or not.

• Job4 : if app is not working , then send email to developer with error messages.

• Job5 Create One extra job for monitoring : If container where app is running. fails due to any reson then this job should automatically start the container again.

Pre-Requisites

• RHEL 8 as Base OS (or you can try on other linux bases OS)
• Docker is installed (if not use the docker.repo in this repository to download it )
• Basics of Linux, Docker, Jenkins
• Docker Images :
  • php named image, which has httpd and php installed
  • py named image, which has httpd and python installed
  • httpd named image, which has httpd installed

Let's Start !

• Create container image that has Jenkins installed using dockerfile, when we launch this image, it should automatically starts Jenkins service in the container.

• First clone this repo somewhere in your RHEL 8 base OS

• Navigate to the cloned repo

git clone https://github.com/tushar5526/Github-Jenkins-Docker
cd Github-Jenkins-Docker

Now we will build the image, that will run the Jenkins as soon as a container is deployed with this image (see Dockerfile RUN java -jar ... command)

docker build -t jenkins .

This is done now, let's move to next step

• First launch a jenkins container

docker run -it -p 8081:8080 -v /var/run/docker.sock:/var/run/docker.sock --name jenkins jenkins

• This launches a jenkins conatainer that has docker installed already, but docker in docker is pretty difficult to manage and handle as well, using --privileged will expose our BASE OS to vulnerabilities as it gives the docker conatiner total access to BASE OS *

THE TRICK

docker runs on docker-daemon which runs in /var/run/docker.sock , so in the line -v /var/run/docker.sock:/var/run/docker.sock we making the docker installed in jenkins container to use daemon of BASE OS, we can still use all the docker commands like launching image and docker ps from the docker in jenkins container

You would get something like this, copy the admin password*

• Create a job chain of job1, job2, job3 and job4 using build pipeline plugin in Jenkins

• If have RHEL on some virtual box, then you can login to jenkins by going to

(base OS IP Address):8081
eg : 192.168.43.64:8081

• If RHEL is your main operating system, then do the following

docker inspect jenkins

• See the IP Address of the docker container

(IP Address of Container):8080

eg : 172.17.0.2:8080

• Now Enter the password you copied earlier and it will login you inside the jenkins

• You change the password of jenkins by clicking on admin in the left panel

• Close windows to install plugins, we will do it later

• Go to *Manage Jenkins

  • Scroll down and select Manage Plugins
  • Go to Available tabs and install :
  • GitHub
  • Build Pipeline
  • Select Restart Jenkins when done

JOB 1 :

• Job1 : Pull the Github repo automatically when some developers push repo to Github.

  • Name this job : Job1
  • You can refer to my Blog www.github.com/tushar5526/jenkinsTest to read about it in detail

*You can GitHub WebHooks as described in my blog, but for simplicity I am using Poll SCM, (POLL SCM will introduce some overhead)

• In Post-Build-Actions select Build-Other-Projects and type Job2, select save and apply

JOB 2:

• 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 PHP, then Jenkins should start the container that has PHP already installed ).

How will this work ?

• I have made a python file which goes into the current workspace and checks the extension of downloaded files and then run respective container ( this file is already placed in jenkins container )

Take a look at python file : launch.py

import os

for file in os.listdir('/root/.jenkins/workspace/Job1'):
  ext = os.path.splitext(file[-1].lower()

  
  if ext == '.php':
    print('running httpd with php container')
    os.system('docker run -it -v /root/.jenkins/workspace/job1/:/var/www/html -p 8082:8080 --name test php')
    break
    
  if ext == '.py':
    print('running httpd with python3 container')
    os.system('docker run -it -v /root/.jenkins/workspace/job1/:/var/www/html -p 8082:8080 --name test python')
    break
    
  if ext == '.html':
    print('running httpd container')
    os.system('docker run -it -v /root/.jenkins/workspace/job1/:/var/www/html -p 8082:8080 --name test httpd')
    break

• Create a job named Job2
• Go to Build
  • Select *Execute Shell
  • Type the following command

  cd /
  python3 launch.py
  

This will launch the container at 8082 port

• In Post-Build-Actions select Build-Other-Projects and type Job34, select save and apply

JOB 3 and JOB 4 :

I will combine both these jobs as it was easy that way

• Job3 : Test your app if it is working or not.

• Job4 : if app is not working , then send email to developer with error messages.

• Make a new job named JOB34

• Go to Build

  • Select *Execute Shell
  • Type the following command

  status=$(curl -o /dev/null -sw "%{http_code}" 192.168.43.64:8082)
  if [[ status==200 ]]; then echo "good";
  else python3 /mail.py;
  fi
  

+

JOB 5 :

• For this we will check test container is working or not every minute and launch a new one if it is not working

PHEW ! Now you can AUTOMATE your development process easily

• Create container image that has Jenkins installed using dockerfile, when we launch this image, it should automatically starts Jenkins service in the container.

• Create a job chain of job1, job2, job3 and job4 using build pipeline plugin in Jenkins

• Job1 : Pull the Github repo automatically when some developers push repo to Github.

• 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 PHP, then Jenkins should start the container that has PHP already installed ).

• Job3 : Test your app if it is working or not.

• Job4 : if app is not working , then send email to developer with error messages.

• Job5 Create One extra job for monitoring : If container where app is running. fails due to any reson then this job should automatically start the container again.

Future Scope :

• Support for backends like node.js
• Integration of Jenkins