Setting up continuous integration on linux

Overview

Continuous integration (CI) is a software engineering practice in which isolated changes are immediately tested and reported on when they are added to a larger code base. The goal of CI is to provide rapid feedback so that if a defect is introduced into the code base, it can be identified and corrected as soon as possible.

The Big picture

 

GIT

It's a distributed version control system. Installing it is a cake walk.

Installation 

Installing for linux

Configuration

Run git --version to be sure in the cmd or terminal depending on your OS.

 

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Gerrit

It's your code review system that intercepts your code push to the repository.

Installation 

Download it here...

Configuration

Gerrit requires a database in which all the reviews history will be stored for later retrieval.Let's setup mysql for the same (however you can use postgres as well).

1. Create a gerrit user on your system

sudo adduser gerrit2

sudo su gerrit2 




2.  Create a gerrit specific user 

   CREATE USER 'gerrit2'@'localhost' IDENTIFIED BY 'your-password';
   CREATE DATABASE reviewdb;
   ALTER DATABASE reviewdb charset=latin1;
   GRANT ALL ON reviewdb.* TO 'gerrit2'@'localhost';
   FLUSH PRIVILEGES;   

3. Initialize the schema 

   java -jar CreateSchema

4. Add indexes

   A script should be run to create the query indexes, so Gerrit can avoid table scans when looking up information. Run the index script through your database's query tool.

   java -jar gerrit.war --cat sql/index_generic.sql | mysql reviewdb -u gerrit2 -p 
   java -jar gerrit.war --cat sql/mysql_nextval.sql | mysql reviewdb -u gerrit2 -p

    

5. Configure site path

   This directory holds server-specific configuration files and assets used to customize the deployment. Gerrit needs read access (but not write access) to the directory. The path is stored in system_config.site_path, so you will need to update the database with this value.

   mkdir /home/gerrit2/cfg
   cd /home/gerrit2/cfg

   UPDATE system_config SET site_path='/home/gerrit2/cfg' 

    

6.   Starting gerrit

   java -jar gerrit.war init --batch -d ~/gerrit_testsite

7.   Observer the result

   http://localhost:8080/login/#/

8.  Gerrit trusts user with keys

   You need to add your public ssh keys to the gerrit for it to authenticate you.

   ssh-keygen -t rsa 

   
   

   Press enter and nothing else till you see a key on your terminal. 

9. Verify your initialization

   ssh user@localhost -p 29418 

10.  Project creation

    ssh -p 29418 user@localhost gerrit create-project --empty-commit --name demo-project

    
    
    For existing projects see this

11. Your first change

    Usually when you push to a remote git, you push to the reference '/refs/heads/branch', but when working with Gerrit you have to push to a virtual branch representing "code review before submission to branch". This virtual name space is known as '/refs/for/branch'

    git clone ssh://user@host:29418/demo-project 

    date > testfile.txt
    

    
    

    git add testfile.txt
    

    
    

    git commit -m "My pretty test commit"
    

    
    

    git push origin HEAD:refs/for/master

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Jenkins

Every time you push a patch you need the tests to be run on it and report should be generated.Well Jenkins does helps you in that.

Installation

Download it here here

Configuration

1.  Start

     java -jar /path/to/jenkins.war --httpPort=port
   
   
   
   
    
    
   
   

2.   Installing a plugin

   1. Start

     java -jar /path/to/jenkins.war --httpPort=port
   
   
   
   

   2. Visit your local jenkins

     http://localhost:port
   
   
   
   

   3.Installing Gerrit Trigger plugin

   This plugin triggers a build when a new patch is pushed into the gerrit (Code Review System).

   Depending on your needs you would have to add new plugins.

   Figure 1 depicts the process.

   
   

   

   Figure 1

    
    
   
   

3.   Configuring the plugin

      Go to Manage plugins -> Gerrit Trigger (After installing it , it should be there)  
   
   
   

    1. Open the plugin

   http://localhost:1234/gerrit-trigger/   

   
   

    

4.   Configure your project server.

    
       
    Follow figure 2 for configuring your server.
   
   
   
   

   

   Figure 2

       
5. 
   

   5.Creating a job for your project

   
   

    
    
   
   

6.   Verifying Jenkins setup

     http://localhost:port/gerrit_manual_trigger/
        Select your project and press search to see if your patchets appear or not.
       With you should be go to go.
   
   
    
    
   
   

7.   Summary

    We clone a git project and we do some changes and push it to gerrit.Inside Jenkins we installed a plugin named GerritTrigger. It has been configured to run a job every time a patch is pushed.

    
   

Let me know if you face any issues in the comment section.