--- title: "How to Create a CI/CD Pipeline for CircleCI Docker Images" description: "Learn how to create a CI/CD pipeline to deploy CircleCI Docker images without messing things up in this step-by-step tutorial!" canonical: "https://adamtheautomator.com/circleci-docker-images/" --- # How to Create a CI/CD Pipeline for CircleCI Docker Images > Learn how to create a CI/CD pipeline to deploy CircleCI Docker images without messing things up in this step-by-step tutorial! Source: https://adamtheautomator.com/circleci-docker-images/ --- ATA Learning Tap to hide [ ATA Learning ](/) * [Home](/) * [Tutorials](/tutorials/) * [Instructors](/author/) * [Advertising](/advertising/) * [Recommended Resources](/resources/) * [About Adam](/about-adam/) Search for: * [](https://twitter.com/adbertram) * [](https://github.com/Adam-the-Automator) * [](https://www.linkedin.com/company/adam-the-automator-llc) * [](/feed/) ![How to Create a CI/CD Pipeline for CircleCI Docker Images](https://adamtheautomator.com/wp-content/uploads/2022/03/How-to-Create-a-CICD-Pipeline-for-CircleCI-Docker-Images.jpg) # How to Create a CI/CD Pipeline for CircleCI Docker Images [![](https://secure.gravatar.com/avatar/9c3cbd45c82cff94f1627c6862c2f3c7425e8c0c9fe804476fbcbad778e178cc?s=192&d=mm&r=g)Muhammed Ali](https://adamtheautomator.com/author/muhammed-ali/)16 March 20227 min. read Categories: [DevOps](/category/devops/) Tags:[Docker](/tag/docker/) Table of Contents * [Prerequisites](#prerequisites) * [Creating a Docker Image of a Python-Based Application](#creating-a-docker-image-of-a-python-based-application) * [Creating a CircleCI CI/CD Pipeline](#creating-a-circleci-cicd-pipeline) * [Activating the CircleCI CI/CD Pipeline](#activating-the-circleci-cicd-pipeline) * [Pushing Changes to GitHub to Trigger the CircleCI Pipeline](#pushing-changes-to-github-to-trigger-the-circleci-pipeline) * [Conclusion](#conclusion) If you’re looking for a way to test and deploy your CircleCI Docker images, creating a CI/CD pipeline can take you a long way to improve software delivery. In this tutorial, you’ll learn how you can potentially develop a CI/CD pipeline for your Docker image using [CircleCI](https://circleci.com/). Read on and deploy your Docker images, only if they pass the test! ## Prerequisites This tutorial will be a hands-on demonstration. If you’d like to follow along, be sure you have the following: * A **[GitHub](https://github.com/)** account and **[GitHu](https://docs.github.com/en/get-started/quickstart/create-a-repo)[b](https://docs.github.com/en/get-started/quickstart/create-a-repo) [repository](https://docs.github.com/en/get-started/quickstart/create-a-repo)** that is already set up. * A [CircleCI account](https://circleci.com/signup/) linked to your GitHub account. * A [Docker Hub account](https://hub.docker.com/). * [Docker](https://docs.docker.com/engine/install/) installed. Related:[How to Install and Use Docker on Ubuntu (In the Real World)](https://adamtheautomator.com/docker-ubuntu/) * A Linux machine – This tutorial uses **[Ubuntu 20.04.3 LTS](https://releases.ubuntu.com/18.04/).** Related:[How to Install Ubuntu 20.04](https://adamtheautomator.com/install-ubuntu/) ## Creating a Docker Image of a Python-Based Application Before jumping to creating a CI/CD pipeline, you’ll first build a Docker image based on a [Python](https://adamtheautomator.com/python-function-return/) application that displays texts on a web browser. You’ll briefly go through how the application is built, write the test cases for the application and then containerize the application. Related:[Related: Getting Started: Python Functions for Newbies](https://adamtheautomator.com/python-function-return/) 1\. Open your terminal, and run the following command to `install` Flask and Pytest. [Flask](https://flask.palletsprojects.com/en/2.0.x/) is a framework used to build web applications in Python while [Pytest](https://docs.pytest.org/en/7.0.x/) is used to write tests Python code. ```bash pip install flask pytest ``` Related:[How To Deploy a Python Flask API Application on Docker](https://adamtheautomator.com/python-flask-api/) 2\. Next, create a project directory with your preferred name, but the project directory is called `flask-circleci` in this demo. This directory is where you’ll store your resources for this tutorial. ```bash mkdir flask-circleci ``` 3\. Create a file called _flask-circleci/main.py_ and populate the following code. The code below displays the “Welcome to my Flask App” text on a home page in a browser. ```python from flask import Flask app = Flask(__name__) #create an instance of the Flask class you just imported @app.route('/') def main(): # display a string in the home page return "Welcome to my Flask App" ``` 4\. Now, create another file called _flask-circleci/test\_main.py and copy/paste the following code._ The code below creates a test client for your application. > _Pytest requires that the name of your test file begins with test\_ as demonstrated below._ ```python from main import app def test_main(): # Creates a test client for this application. response = app.test_client().get('/') # assert the stutus code of the page('/') is 200 assert response.status_code == 200 # assert the return statement to the page assert response.data == b'Welcome to my Flask App' ``` 5\. Run the following commands to navigate to your project directory (`flask-circleci`), run the test for your project. ```bash cd flask-circleci pytest ``` If the test succeeds, you’ll get 100% progress, as shown below. ![Running Test for the Project](https://adamtheautomator.com/wp-content/uploads/2022/03/image-211.png) Running Test for the Project 6\. Next, create a text file (_requirements.txt_) to document your dependencies in the root directory and populate the text below. This file is essential when building your Docker image so that it works properly. ```powershell Flask==2.0.3 pytest==6.2.5 ``` 7\. Lastly, create a new file (_flask-circleci/Dockerfile)_, and write the instructions below to the _Dockerfile_ to build your Docker image. The instructions in the _Dockerfile_ perform the following: * Create a file in your image. * Copies all the files in the files in the current directory (_flask-circleci_). * Run your code ```docker # set the Base Image from which your image will be built on FROM python:3.8 # create a directory called flask-circleci in root. # This directory will contain the code which currently resides in RUN mkdir /flask-circleci # make /flask-circleci the working directory WORKDIR /flask-circleci # copy your requirements file to the directory you just created COPY requirements.txt /flask-circleci RUN pip install -r requirements.txt # copy the current directory in you local machine to /flask-circleci in your image ADD . /flask-circleci EXPOSE 5000 CMD python main.py ``` ## **Creating a CircleCI CI/CD Pipeline** Now you have your Docker image ready, you’ll create a CI/CD pipeline to test your code, and if all tests pass the Docker image and pushed to [Docker Hub](https://hub.docker.com/). Docker Hub is a service like GitHub, but for Docker images, that helps you find and share container images with your team or other developers. Related:[How to Create a Jenkins CI CD Pipeline](https://adamtheautomator.com/jenkins-ci-cd/) To create the CI/CD pipeline, follow the steps below: 1\. Open your favorite web browser and log in to your [Docker Hub account](https://hub.docker.com/login). 2\. On the Docker Hub home page, click on the **Create Repository** option to create a repository on Docker Hub. ![Creating a Repository](https://adamtheautomator.com/wp-content/uploads/2022/03/image-212.png) Creating a Repository 3\. Set a unique name for your repository. This tutorial uses a repository called **circleci-tutorial**, as shown below. ![Naming and Creating the Docker Hub Repository](https://adamtheautomator.com/wp-content/uploads/2022/03/image-213.png) Naming and Creating the Docker Hub Repository 4\. Create a new file (_flask-circleci/config.yml)_ at the root of your project, and copy/paste the code below to the _config.yml_ file. The code below gets a ready-made Python image and uses it to install the dependencies and run the unit tests to build and push your Docker image to your repository Docker Hub. > _Typically, for a live project, you’d want to put your username and password protected within CircleCI or maybe in a .env file._ ```yaml version: 2 # Version of CircleCI jobs: build: docker: - image: python:3.8 steps: - checkout - run: # creates a virtual environment for you project, # install dependencies in it and run tests name: Run unit tests command: | python3 -m venv venv . venv/bin/activate pip install -r requirements.txt pytest # Creates a remote Docker environment configured to execute Docker commands. - setup_remote_docker - run: # installs a docker client that will be used to run the docker commands name: Install Docker client command: | set -x VER="17.03.0-ce" curl -L -o /tmp/docker-$VER.tgz https://get.docker.com/builds/Linux/x86_64/docker-$VER.tgz tar -xz -C /tmp -f /tmp/docker-$VER.tgz mv /tmp/docker/* /usr/bin - run: # Builds a docker image to push to Docker Hub # Tag (-t) pattern is below, where CircleCI # to get the Dockerfile from the current directory. # . name: Build Docker image command: docker build -t khabdrick/circleci-tutorial:v1 . - run: # Pushes the Docker image you created to the Docker Hub. # Replace khabdrick/circleci-tutorial:v1 with the # you used to build the image above name: Push to Docker Hub command: | docker login -u username -p password docker push khabdrick/circleci-tutorial:v1 ``` 5\. Finally, run the following commands on your project’s root to `commit` and `push` the code (_flask-circleci/config.yml_) to your GitHub repository. ```bash git add . # adds changes to staging area git commit -m "update" # commits your changes git push # Push to GitHub ``` ## Activating the **CircleCI CI/CD Pipeline** You’ve just created your CircleCI CI/CD Pipeline, but right now, it’s just sitting there and not doing much. You’ll have to activate your pipeline by setting up a project in your CircleCI account. 1\. Log in to your [CircleCI account](https://circleci.com/vcs-authorize) with your GitHub account on your web browser. 2\. Next, click the **Projects** tab on the left panel, and click the **Set Up Project** button on the right side of your project to activate the CircleCI pipeline on the project. Since you logged in to CircleCI with your GitHub account, your projects sync with CircleCI, like in the image below. ![Setting up a Project](https://adamtheautomator.com/wp-content/uploads/2022/03/image-214.png) Setting up a Project 3\. Navigate back to the **Dashboard** tab and you’ll see the **Success** status. The **Success** status indicates everything ran as expected, and the image has been pushed to your Docker Hub repository. Click on build to see all the steps that ran in the pipeline. ![Viewing Project Status](https://adamtheautomator.com/wp-content/uploads/2022/03/image-215.png) Viewing Project Status Below, you can see the list of steps CircleCI took to run the pipeline. ![Viewing Steps that Ran the Pipeline](https://adamtheautomator.com/wp-content/uploads/2022/03/image-216.png) Viewing Steps that Ran the Pipeline 4\. Finally, switch back to your Docker Hub repository, and you’ll see the image you pushed to Docker Hub through the CircleCI pipeline. ![Viewing Pushed Image in Docker Hub Repository](https://adamtheautomator.com/wp-content/uploads/2022/03/image-217.png) Viewing Pushed circleci docker images in Docker Hub Repository ## Pushing Changes to GitHub to Trigger the CircleCI Pipeline By now, you already have a working CircleCI pipeline. But perhaps you made changes to your project. If so, how would you know the pipeline still works? You can trigger CircleCI by pushing changes to your GitHub repository and see if the test will succeed. 1\. On your local machine, replace the code you have in _test\_main.py_ with the code below. The code below purposely ensures the test fails because the status code changed from `200` to `400`. ```python from main import app def test_main(): # Creates a test client for this application. response = app.test_client().get('/') # assert the status code of the page('/') is 400 when it isn't, # causing the test to fail. assert response.status_code == 400 # assert the return statement ton the page assert response.data == b'Flask App' ``` 2\. Next, replace the `steps` in the _config.yml_ that builds the Docker image and pushes it to Docker Hub with the code below. In the code below, you’re just changing the version to ensure sure only new changes are pushed to your GitHub repository. ```yaml - run: name: Build Docker image command: docker build -t khabdrick/circleci-tutorial:v2 . - run: name: Push to DockerHub command: | docker login -u username -p password docker push khabdrick/circleci-tutorial:v2 ``` 3\. Run the following commands on your project’s root to `commit` and `push` the code to your GitHub repository. ```bash git add . # adds changes to staging area git commit -m "v2" # commits your changes git push # Push to GitHub ``` 4\. Now, navigate to your CircleCI dashboard, and you’ll see that the build **Failed**, as shown below. Click on build to see the steps taken to push the changes and confirm what caused the build to fail. ![Viewing Project Status (Failed)](https://adamtheautomator.com/wp-content/uploads/2022/03/image-218.png) Viewing Project Status (Failed) ![Showing Failed Tests](https://adamtheautomator.com/wp-content/uploads/2022/03/image-219.png) Showing Failed Tests 5\. Lastly, navigate to your Docker Hub repository and confirm the changes were not pushed. As you can see in the image below, v2 wasn’t uploaded because the test failed. ![Viewing Repository in Docker Hub](https://adamtheautomator.com/wp-content/uploads/2022/03/image-220.png) Viewing Repository in Docker Hub ## Conclusion Throughout this tutorial, you’ve learned how to write tests, and Dockerize your Python application. You’ve created a CI/CD pipeline with CircleCI that runs the test for your application and pushes your Docker image to Docker Hub. At this point, you already have a foundational knowledge of developing a CI/CD pipeline with CircleCI. Now, how do you intend to use this newfound knowledge? Perhaps creating a [CI/CD pipeline that deploys your Docker image to Heroku](https://medium.com/hackernoon/ci-cd-pipeline-using-github-docker-circleci-heroku-ef7f8a90a6f9)? Share this article [Share on X](https://twitter.com/intent/tweet?url=https%3A%2F%2Fadamtheautomator.com%2Fcircleci-docker-images%2F&text=How%20to%20Create%20a%20CI%2FCD%20Pipeline%20for%20CircleCI%20Docker%20Images)[Share on Facebook](https://www.facebook.com/sharer/sharer.php?u=https%3A%2F%2Fadamtheautomator.com%2Fcircleci-docker-images%2F)[Share on LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fadamtheautomator.com%2Fcircleci-docker-images%2F) ## Related Posts ![](https://adamtheautomator.com/wp-content/uploads/2026/02/featured_image-13.webp) ### [Azure Container Apps: Instant Preview Environments per PR](/build-ephemeral-preview-environments-every-pr/) Build isolated preview environments for every pull request using Azure Container Apps revision labels and Azure DevOps pipelines with scale-to-zero economics. ![](https://adamtheautomator.com/wp-content/uploads/2025/11/55418e927e511ae263219c072e27d637c2a967a5036de7020b329582db775c26.png) ### [Automating Docker Container Health Checks with Python and Local Notifications](/docker-health-checks-python/) Docker's built-in health checks are passive—they tell Docker when a container fails, but do they tell you? 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