Continuous Integration/Continuous Deployment (CI/CD) has become the most common development practice in the last decades for software development. Therefore, many CI/CD automation platforms emerged to get the most out of CI/CD. One of the most powerful among them is CircleCI. This article will pass by answers to questions about what is CI/CD and CircleCI? and a few of its concepts.

What is CI/CD?

CI/CD as development practice has proven its efficiency to empower software teams doing great work of building, testing, and deploying applications in an easier and quicker workflow.

Whereas Continuous Integration (CI) increases the work integrating of each developer several times daily inside the repository. The goal is to detect integration errors as quickly as possible and speed up the collaborative development process. At the same time, Continuous delivery or deployment (CD) focuses on reducing conflicts that occur at the deployment or phase. It also automates the process of deploying a build to make the code releases successfully all the time over and over again.

Continuous deployment has many benefits in different ways , such as:

  • Facilitating standardizing application deployment process.
  • Keeping every work recorded and archived.
  • Preventing repetitive steps to focus more on the coding.

CircleCi Definition

CircleCI is a commonly used CI/CD automation platform. It enables developer teams to build and integrate their workflows for software projects. CircleCI can give you a unified plan through every variety of development, testing, deployment processes.

CircleCI aims to increase the speed and efficiency of technology organizations’ development and engineering teams. This is achieved by creating intelligent automation platforms such as CircleCI. CircleCI is also featured by providing enterprise-level services and support alongside the resilience of startups. Furthermore, it supports every OS platform that organizations can have: Linux, macOS, Android, and Windows, either on-premise or Cloud.

CircleCI Benefits

As the above description, CircleCI has many tangible benefits that reflex on the whole deployment process like:

  • CircleCI can run complex jobs faster. So, organizations choose it. CircleCI is also configuring many pipelines with sophisticated caching efficiently. It is running more than one million development jobs daily for more than 30,000 organizations.
  • Enables developers to SSH into any job and debugs build bugs. Also, you can set up parallelism in a .circleci/config.yml file contains constructions that boost the jobs and configure caching to benefit from reusing data of previous jobs.
  • Provides monitoring insights tool for the builds in addition to Nomad scheduling for CircleCI on-premise users and administrators.
  • Perform automated tests for GitHub and Bitbucket authorized projects in a new separated container or virtual machine.
  • Provide and send code test results in detailed notifications via email, Slack, and IRC.
  • Can work and configured to deploy code in traditional and multi-cloud environments like AWS different container services, Kubernetes, Heroku, and Azure. In addition to the ability to add other cloud deployments by SSH or by API client.


CircleCI has many core and complementary concepts. In this brief article, we will suffice with taking a quick glimpse about a few of them:

  • Projects: CircleCI should share the related code repository name in the VCS of GitHub or Bitbucket. You can choose the “Add Project” option to see the “Projects dashboard” in the CircleCI application. 
  • Configuration: Beginning of the “configuration as code” slogan, CircleCI can orchestrate the entire continuous integration and deployment work. It put them in an all-in-one YAML configuration config.yml file. It is created in the .circleci at the root folder of your product.
  • Jobs: The term “jobs” are the basic blocks of your project config. Ther are just a collection of steps that runs the required scripts. And each job has its own determined executor like Docker, windows, or macOS, or it runs in the default image.
  • Workflows: It determines a bunch of jobs with their run instruction. You can also run jobs at the same time, on a schedule, sequentially, or by a manual gate.

Hello World CircleCI

You can build CircleCI in Linux, Android, Windows, or macOS. Here is an example of echo “Hello World” building from CircleCI on Linux.

The example can work by inserting a new job called build to run a container called “pre-built CircleCI Docker image for Node”. It creates a directory named .circleci in the root directory. Then it makes a config.yml file containing code commands that create the “Hello World” job, such as:

  - image: cimg/node:14.10.1
  - checkout
  - run: echo "hello world"

After more advanced configuring steps, you will have “Hello World” printed in your workflows page console.

Other CircleCI Concerns

To make a clearer CircleCI understanding, it is worth clarifying most of the other CircleCI concerns that relate directly to this article’s brief goals.

  • CircleCI spy code: CircleCI and employees never see any code without real permission. Just when you need support, the support team may ask permission to see the code only to help fix the problem.
  • CircleCI for enterprises: CircleCI platform and services are available to suit enterprise clients’ needs. There are more details in the “Administrator’s Overview”, in addition to the installation instructions.
  • Differences between CircleCI’s hosting options: These differences are that the Cloud CircleCI controls the setup, infrastructure, security, and services maintenance. CircleCI decreases manual work through automatic updates and instant access to new feature releases. In the server, you also can run CircleCI via AWS service for instance. You can keep your servers behind team and policy firewall. You can also administrate and customize upgrades when new versions are released.
  • The number of CircleCI jobs can run at one time: This number is determined by the number of containers in your plan. If you have only ten containers in your plan, you can not run more than ten workflow jobs, and so on. And by configuring the workflow you can run multiple jobs at the same time. 
  • CircleCI support for different operating systems: CircleCI supports most operating systems; Linux, iOS, Windows, and Android. However, the support for Linux is the best for most applications.