What is continuous integration and why it is important

CI is a safety net that lets developers prevent many issues before
they reach users. As a result, they ship code with more confidence,
but not necessarily faster — the deployment process may still be
manual, long, and complicated.

Marko Anastasov - сofounder of SemaphoreCI.com

CI helps development teams avoid “integration hell” where the software
works on individual developers’ machines, but it fails when all
developers combine (or “integrate”) their code.

Rod Cope - CTO at Rogue Wave Software

Continuous integration combines the integrate and test function,
following the initial code/build process of agile development. It
focuses on streamlining development, integrating code into shared
repositories, and automating builds and tests to make it easier to
prevent and find problems more quickly.

Yaniv Yehuda - co-founder and CTO of DBmaestro

Benefits of continuous integration

Benefits for business owners

• Accelerates time to market as your customers get upgrades faster
• Reduces company’s expenses on manual labor
• Increases productivity of your team by automating the tedious tasks
• Helps to release a qualitative and error-free software

Benefits for developers

• Faster debugging
• Running the tests in the cloud
• Frequent deployment
• Running tests in a real-world stating environment
• Visisble progress of developers

Сontinious integration and delivery tools

• Completely free
• Hundreds of plugins
• Jenkins is available for all platforms and different operating systems, whether OS X, Windows or Linux
• Open-source and supported by a large community

• Makes it easy to test projects in any environment, device and operating system as it’s hosted on the cloud
• Supports dozens of programming languages
• Runs tests on Linux and Mac OS X simultaneously

• Supports multiple platforms such as Unix, Windows, macOS, and any other platform that supports Go
• Supports multiple platforms such as Unix, Windows, macOS, and any other platform that supports Go.
• Parallel builds
• Real-time logging
• Local testing
• Autoscaling
• Docker support
• Built-in container registry

• Compatible with Python, Node.js, Ruby, Java, Go
• Provides a free plan even for enterprise projects
• No dedicated server required
• Ability to install Circle CI on a private server
• Automatic debugging feature
• Runs in Docker containers, Linux VMs and macOS VMs
• Connects with your toolchain like Github, Bitbucket, Fastlane, Azure, and Slack

How to set up continuous integration in CircleCI

• NodeJS
• create-react-app
• GitHub account

git init

git add .

git commit -m “init”

git remote add origin https://github.com/tarasromil/ci.git

git push -u origin master

version: 2 CircleCI API version
jobs:
 build:
   docker:
   Specify the version you desire here. I'm using 9.11.1
   - image: circleci/node:9.11.1

   Set a working directory
   working_directory: ~/ci

   Describe the steps you will conduct
   steps:
   - checkout

   Restore your cash
   - restore_cache:
       keys:
         Here you should indicate the unique key for your cache to increase the build performanceТ
         I use "package.json" and ".circleci/config.yml"
       - v1-dependencies-{{ checksum "package.json" }}-{{ checksum ".circleci/config.yml" }}

   Re-install node_modules for current version
   - run: yarn install

   Now let’s save new cache
   - save_cache:
       paths: We can indicate several directories or files for cashing - let’s make do with modules
       - node_modules
       Indicate a new key for our cache
       key: v1-dependencies-{{ checksum "package.json" }}-{{ checksum ".circleci/config.yml" }}

   Run the tests
   - run: yarn test

run:
   name: Creating artifacts directory
   command: mkdir /tmp/artifacts
run:
   name: Creating test result directory
   command: mkdir -p /tmp/junit/mocha
run:
   name: Run tests
   command: yarn test
store_test_results:
   path: /tmp/junit
store_artifacts:
   path: /tmp/artifacts

jobs:
 build: ...
 deploy:
   machine:
     enabled: true
   working_directory: ~/ci
   environment:
     HEROKU_APP: "sleepy-refuge-55486"
   steps:
     - checkout
     - run:
         name: Deploy Master to Heroku
         command: |
           git push https://heroku:[email protected]/$HEROKU_APP.git master

workflows:
 version: 2
 build-and-deploy:
   jobs:
     - build

Conclusion