Continuous Integration

Learning Goals

• Students can explain the benefits of using continuous integration
• Students understand the steps used in the practice of CI
• Students can utilize a CI service on a Github repo to automate testing code changes

Intro (10 min)

Read What is Continuous Integration?

Discuss with the person next to you:

• What is CI?
• Why would we want to use it?

Continuous Integration

What is CI?

Continuous Integration is a development practice of routinely merging in code changes into a central repository and testing these changes as early and often as possible. The CI process entails both a automation aspect such as a CI platform or build service and a cultural aspects of integrating more frequently.

What are the benefits?

• Identify conflicts early
• Find and address bugs quicker
• Avoid Integration Hell
• Improve Software Quality

What are the steps?

1. Write tests for all critical parts of the code base
2. Use a CI service to run those tests automatically with all repo changes
3. Make sure team integrates as early as possible
4. Fix broken build ASAP
5. Write tests for all new features

Utilizing Travis CI

Step 1. Create Rails Repo

1. Create new Application

   rails new tweet-saver
   

2. Scaffold the app

   rails generate scaffold Tweet message:string published:boolean
   

3. Run app to make sure everything is working

   rails server
   

4. Run tests to make sure everything is working

   rake
   

Step 2. Push App to Github

1. Initialize a new git repo
2. Add your new changes and link up a remote from your new Github repo
3. Push up changes like you always do

Step 3. Sign up for Travis CI

1. Go to Travis CI Github App
2. Add the tweet-saver repo
3. Confirm you can see you repo on Travis CI
4. Change settings to NOT ‘Build Pushed Branches’

Step 4. Add Travis config to trigger initial build

1. Create .travis.yml file in your tweet-saver project

   language: ruby
   rvm:
    - 2.4.1
   

   Hint: Be sure to use your ruby version

2. Add .travis.yml file to git, commit, & push
3. Go to your dashboard in travis - confirm that the build PASSED
4. Go to your repo in github and notice the dot next to the commit

Step 5. Let’s break the build

1. Create a new branch break-the-build
2. BREAK IT - sabotage test
3. Commit changes and push to Github
4. Create a PR and watch the magic happen

What do you see on Github? What do you see on Travis CI?

Don’t Break the Build - Example Issues

• Forgetting a new asset or file
• Not running tests locally
• Inconsistent dependency versions

Continuous Integration vs Continuous Delivery

Continuous delivery is an extension of CI that deploys code changes automatically to a specific environment (i.e testing, staging, production) after the build stage.

It is also known as the process of releasing code frequently to the end user (daily, weekly, etc) based typically on business requirements.

Where have you already seen this? cough, cough Github pages?

Many CI platforms have these features built in and can automatically deploy your application after your code is merged. Auto Deploy With Travis CI and Heroku