Continuous Integration (CI)

• Continuous Integration (CI)

  • What

  • Why

  • How

  • Example workflow

  • Team responsibilities

  • Example

What

• the practice of automating the integration of code changes from multiple contributors into a single software project.

• he CI process is comprised of automatic tools that assert the new code’s correctness before integration.

• A source code version control system is the crux of the CI process.

• The version control system is also supplemented with other checks like automated code quality tests, syntax style review tools, and more.

• development practice that requires developers to integrate code into a shared repository several times a day

• the process of automating the build and testing of code every time a team member commits changes to version control

Why

• By integrating regularly, you can detect errors quickly, and locate them more easily.

• Because you’re integrating so frequently, there is significantly less back-tracking to discover where things went wrong

  • can spend more time building features.

• Continuous Integration is cheap

• No CI, leads to longer periods between integrations. This makes it exponentially more difficult to find and fix problems.

• Increase visibility enabling greater communication

• Catch issues early and nip them in the bud

• Stop waiting to find out if your code’s going to work

  • Especially just before deployment

• deliver software more rapidly

• Waiting days or weeks to integrate code creates many merge conflicts, hard to fix bugs, diverging code strategies, and duplicated efforts.

  • CI avoids this by integrating early and often

• CI keeps the master branch clean

How

• Maintain a single source repository

• Automate the build

  • Use a CI tool that has a hook to your git repo on master branch

  • Tools like jenkins, teamcity, gocd

• Make your build self-testing

• Every commit should build on an integration machine

• Keep the build fast

• Test in a clone of the production environment

• Make it easy for anyone to get the latest executable version

• Everyone can see what’s happening

• Automate deployment

Example workflow

• Developers check out code into their private workspaces

• When done, commit the changes to the repository

• The CI server monitors the repository and checks out changes when they occur

• The CI server builds the system and runs unit and integration tests

• The CI server assigns a build/binary label to the version of the code it just built

• The CI server releases deployable artefacts stored in an artefact repository for testing

• The CI server informs the team of the successful build

• If the build or tests fail, the CI server alerts the team

• The team fixes the issue at the earliest opportunity

• Continue to continually integrate and test throughout the project

Team responsibilities

• Check in frequently

• Don’t check in broken code

• Don’t check in untested code

• Don’t check in when the build is broken

• Don’t go home after checking in until the system builds

Example