Best of 2023: Building a CI/CD Pipeline With Kubernetes
As we close out 2023, we at Cloud Native Now wanted to highlight the most popular articles of the year. Following is the latest in our series of the Best of 2023.
A CI/CD pipeline is a series of automated processes that developers use to build, test and deploy software quickly and efficiently. It is a methodological approach aimed at enhancing the speed of software development and improving its quality.
Continuous integration (CI) is the first part of the pipeline. It involves developers merging their changes back to the main branch as often as possible. The primary objective of CI is to prevent integration problems, which are common when developers work on different parts of a software project separately.
Continuous deployment (CD) is the second part of the pipeline, which comes after successful CI. CD automates the delivery of applications to selected infrastructure environments. Most teams work with multiple environments, such as development, staging and production environments, and CD ensures there is an automated way to promote code changes through these environments, all the way to production.
The CI/CD pipeline is the backbone of DevOps, enabling rapid software changes while maintaining system stability and security. But to truly unlock its potential, it’s ideal to pair it with a robust container orchestration platform like Kubernetes.
How Are CI/CD Pipelines Different in Kubernetes?
Advanced Deployment Strategies
The deployment strategy in Kubernetes’ CI/CD pipelines is another distinguishing factor. Kubernetes provides several built-in deployment strategies, such as recreating and rolling updates. With some tweaking, you can also achieve progressive delivery techniques like Blue/Green and canary.
For instance, the rolling update strategy gradually replaces instances to avoid downtime. In a blue/green deployment, two environments are maintained – the “Blue” environment runs the current application version, while the “Green” environment is used to test the new version. Once the new version is tested and ready, the traffic is switched from blue to green. A canary deployment involves releasing the new version to a small subset of users before a full rollout. This approach is useful for testing the new version in a real-world setting.
Environment Isolation
With Kubernetes, each application runs in a separate container, ensuring that the application’s environment is isolated from others. This isolation prevents conflicts between different applications and their dependencies. It also enhances security by limiting the potential impact of a security breach to a single container.
Moreover, Kubernetes allows for finer-grained control over resource allocation. Developers can specify the exact amount of CPU and memory each container should use. This ensures that no single application can monopolize the system’s resources, leading to a more stable and efficient system.
In addition to isolation at the application level, Kubernetes provides logical isolation between different parts of a cluster. This is achieved through the use of namespaces, which are virtual clusters within a Kubernetes cluster. Each namespace has its own network policies, which control the traffic between pods in the namespace.
Immutable Infrastructure
Lastly, Kubernetes’ approach to CI/CD pipelines is characterized by the concept of immutable infrastructure. This means that once a component is deployed, it is never modified, only replaced with a new version. This approach avoids configuration drift, where small, incremental changes over time lead to a system that is different from its original state.
In Kubernetes, each container is created from a specific image, and once it is running, it cannot be modified. If a change is required, a new image is created and a new container is deployed from that image.
This approach has several advantages. First, it leads to more predictable deployments, as each container is identical to the one tested in the staging environment. Secondly, it reduces the risk of errors, as there is no chance of accidentally modifying a running container. Finally, it simplifies rollbacks, as developers can simply deploy a previous version of the image if something goes wrong.
CI/CD Tools Built for Kubernetes
When building your Kubernetes CI/CD pipeline, you can leverage tools designed for a cloud-native ecosystem. Here are a few popular tools to consider:
ArgoCD
ArgoCD is an open source, GitOps-based continuous delivery tool for Kubernetes. It leverages Git as a single source of truth for declarative infrastructure and applications, providing a mechanism to manage Kubernetes-native applications directly from Git repositories.
The first aspect of ArgoCD is its declarative approach. Your desired application state is described in a Git repository. ArgoCD constantly monitors this repository and ensures that your application’s actual state in the Kubernetes cluster matches the desired state described in Git. This approach not only simplifies deployment but also provides a clear audit trail.
Secondly, ArgoCD emphasizes the principle of GitOps. This means all changes to the application are made via git commits, providing a unified and version-controlled history of all changes. This approach enhances traceability and makes rollbacks straightforward.
Lastly, ArgoCD supports a multitude of configuration management tools like Kustomize, Helm, Jsonnet and others. This means you can manage complex application configurations with ease, making ArgoCD a flexible choice for building CI/CD pipelines with Kubernetes.
Codefresh
Codefresh is another CI/CD tool designed specifically for Kubernetes. One of the key features of Codefresh is its built-in Docker and Helm support. This allows you to build Docker images and Helm charts directly within the pipeline, resulting in a streamlined workflow. Moreover, it offers a visual interface for Helm releases, providing a clear overview of the deployment process.
Codefresh also offers a unique live debugging feature. This allows you to debug your pipelines in real-time, leading to faster troubleshooting and shorter development cycles.
Lastly, Codefresh provides integration with major Git providers and Kubernetes clusters, ensuring seamless deployment of applications. With its rich features and Kubernetes-centric design, Codefresh is certainly worth considering for your CI/CD pipeline.
Jenkins X
Jenkins X is a CI/CD solution for modern cloud applications on Kubernetes. It extends the popular Jenkins CI/CD server with additional functionalities to fully embrace the power of Kubernetes.
Jenkins X comes with automated CI/CD. As soon as you commit the code to the repository, Jenkins X automatically triggers the pipeline, builds the Docker image, pushes it to the Docker registry, and deploys it to the Kubernetes cluster.
Jenkins X also provides a Preview Environment feature. Whenever a pull request is created, Jenkins X automatically spins up a preview environment to test the changes. This allows for faster feedback and better collaboration between team members.
GitLab CI/CD
GitLab CI/CD is an integral part of the GitLab platform, a single application for the entire DevOps lifecycle. It provides a robust and flexible framework for creating CI/CD pipelines.
GitLab CI/CD uses a file called ‘.gitlab-ci.yml’ to define the actions that should be executed at specific stages of the pipeline. This allows for granular control over the CI/CD process and the flexibility to adjust the pipeline according to specific project needs.
Another feature of GitLab CI/CD is Auto DevOps. It automatically configures your CI/CD pipeline with best practices, significantly reducing the initial setup time. It includes functionalities like Auto Build, Auto Test and Auto Deploy.
Additionally, GitLab CI/CD provides extensive metrics and insights about your pipelines. This includes pipeline success rate, duration and more. These metrics can be invaluable for identifying bottlenecks and improving your CI/CD process.
Building a CI/CD Pipeline With Kubernetes
Set Up a Kubernetes Cluster
The first step in building a CI/CD pipeline with Kubernetes is to set up a Kubernetes cluster. A cluster is a set of machines, known as nodes, that run containerized applications. This cluster is the heart of your Kubernetes setup, where all the tasks related to orchestrating your containers will occur.
Setting up a Kubernetes cluster involves several steps, including choosing a hosting provider or provisioning servers on-premises, installing Kubernetes on your nodes and configuring your cluster to suit your needs. Once your cluster is set up, you can start deploying your applications and services to it.
Build the CI Pipeline
The CI pipeline is the first half of the CI/CD pipeline. It mainly involves the integration and testing of code from different developers. Let’s delve into the steps involved in building a CI pipeline.
Automate Code Checkout
The CI process begins with code checkout. This involves pulling the latest code from your repository, typically stored in version control systems like Git. Automating this process ensures that the CI pipeline always has the most recent version of your software code to work with, thereby minimizing integration issues.
Dependency Installation
The next step involves the installation of dependencies. These are the libraries or packages that your software needs to run correctly. Automating the installation of dependencies ensures that your software has all the necessary components it needs to function properly. It also helps in maintaining consistency across different environments, thereby reducing the chances of discrepancies and errors.
Run Tests
Running tests is a crucial part of the CI pipeline. It involves executing your suite of tests against the integrated code to check for any errors or issues. Automated testing ensures that any bugs or issues are spotted and fixed as early as possible, thereby improving the quality of your software.
Build Container Image
Once the tests have passed, the next step is to build a container image. A container image is a lightweight, standalone package that includes everything needed to run an application: the code, runtime, system tools, and libraries. Building a container image ensures that your application can run consistently across different environments.
Push Image to Registry
The final stage of the CI pipeline is pushing the container image to a registry. A registry is a repository for storing and distributing container images. It ensures that the image is readily available for deployment in the Continuous Deployment (CD) pipeline.
Build the CD Pipeline
The CD pipeline is the second half of the CI/CD pipeline. It primarily involves the deployment of the container image to the production environment. Let’s explore the steps involved in building a CD pipeline.
Configure Deployment Triggers
Deployment triggers are events that initiate the deployment process. They could be anything from a successful CI pipeline run to a manual trigger by a developer. Configuring deployment triggers ensures that your application is deployed to the production environment as soon as it’s ready, thereby reducing the time to market.
Rolling Deployment
Rolling deployment is a deployment strategy where the new version of an application is gradually rolled out to users. It involves deploying the new version to a small set of servers or users, monitoring the application’s performance, and gradually rolling it out to more servers or users if no issues are detected. Rolling deployment minimizes the risk of errors and helps ensure a smooth transition to the new version.
Conclusion
Building a CI/CD pipeline with Kubernetes can significantly enhance your software development process, making it more efficient, reliable and robust. It not only automates repetitive tasks but also helps in catching bugs early, reducing the time to market, and ensuring a smooth and risk-free deployment. Whether you’re a seasoned Kubernetes user or just starting in the field, understanding and implementing a CI/CD pipeline with Kubernetes is a skill worth mastering.
