What is GitOps?
GitOps, initially proposed by Weaveworks in 2017, uses Git as a "single source of truth" for CI/CD processes, integrating code changes in a single, shared repository per project and using pull requests to manage infrastructure and deployment.
GitOps is a way to do a Continuous Delivery process. It is an operating model for building Cloud Native applications that unify Deployment, Monitoring, and Management. It works by using Git as a source of truth for declarative infrastructure and applications. Automated CI/CD pipelines roll out infrastructure changes when commits are pushed and approved in Git. It also uses diff tools to compare the actual production state with what's under source control and alerts when there is a divergence. The ultimate goal of GitOps is to speed up development so that teams can make changes and updates safely and securely to complex applications running in Kubernetes(k8s). GitOps delivers an application with a standard workflow for application management. It also helps in improving reliability with visibility and version control through Git.
A single source of truth for infrastructures like declarative infrastructure and applications. Taken From Article, Gitops Tools and Use Cases
What are the Principles of GitOps?
GitOps Principles
The Entire System is Declarative
Declarative means that configuration is guaranteed by a set of facts instead of by a set of instructions. Kubernetes is a modern cloud-native tool that is "declarative," and that can be treated as code. Apps can be easily deployed and rolled back to and from Kubernetes. And even more importantly, when disaster strikes, the cluster's infrastructure can also be dependably and quickly reproduced.
The Required Version System is Git
Git is a single source where everything is stored, including various features such as rollbacks, commit history, revert, rebase, etc. Users can use SSH keys to sign commits to enforcing robust security mechanisms and code protection.
Approve Changes Automatically
Allows change to state to be automatically applied to the system; there is a suggested environment that the state definition lives outside of, allowing users to separate what they do and how they will do it.
Software Agents Ensure Efficiency and Correctness
Software agents inform users whenever reality doesn't match expectations. The use of agents also ensures that the entire system is self-healing. And by self-healing, I don't just mean when nodes or pods fail—Kubernetes handle those. They act as the feedback and control loop for such operations.
GitOps with Kubernetes
GitOps treats each software or infrastructure component as one or more files in a version control system(VCS), with an automated process to synchronize the state between version control and the runtime environment. An orchestration system like Kubernetes(k8s) is essential for achieving this. Without Kubernetes, the overall infrastructure, with multiple, incompatible technologies, can be too complex to manage. It helps address these issues and has influenced the evolution of IaC practices. The growth of Kubernetes enabled the creation of tools for implementing GitOps.
Configuration of GitOps with Kubernetes
Workflow changes with Kubernetes.
- Developers push their code to the application repository.
- Doing changes trigger the build pipeline, resulting in the application's build.
- Build pipeline publishes a container image with a new application version.
- The environment repository stores the Kubernetes configuration manifest file, updated to use the new container image version.
GitOps follow the principles to manage infrastructure and application configuration over git repository. Taken From Article, GitOps Challenges and Solutions
Kubernetes GitOps Checklist
Below described Kubernetes GitOps Checklist:
Kubernetes
Adopting an essential core technology for containers and infrastructure management is a crucial demand. It helps organizations manage workflows efficiently, accelerate application development, and meet market demand faster. Besides coordinating containers, Kubernetes can also manage hardware and offers essential middleware elements for managing data.
Team Knowledge and Culture
To implement the methodology of DevOps/GitOps in the organization, the development team must be aware and willing to become accustomed to new processes to save actual time. The team should handle experimentation, trials, mistakes, and training to understand new workflows, tools, and techniques while moving forward to new methods.
GitOps Pipeline
First, it's not the CI system conducting the deployment. Second, a GitOps agent (such as Harness Continuous Deployment) should be deployed in the Kubernetes clusters such as AKS, EKS, Bare Metal, OpenShift, etc.). Last but not least, introducing a configuration repository that will declare the state in which the user wants that environment to be.
Delivery
The process of implementing and upholding security compliance best practices or regulations in the software delivery pipeline is known as trusted delivery. These barriers are implemented utilizing policy-as-code and take the form of codified policies in the software development lifecycle.
Flux for Implementing GitOps
Flux is one of the GitOps operators for Kubernetes. It is an open-source tool developed by Weaveworks and later donated to the Cloud Native Computing Foundation. It runs in the cluster used to manage, and its primary function is to watch a remote repository describing the cluster state. It reconciles changes to converge the current cluster state to the desired state.
- Flux provides GitOps for both apps and infrastructure
- Push to Git, and Flux does the rest
- Flux works with your existing tools
- Flux is designed with security in mind
- Flux works with any Kubernetes and all standard Kubernetes tooling
- Flux does Multi-Tenancy (and "Multi-everything")
- Flux alerts and notifies
Flux Configuration
When you're getting ready to install Flux, there are a few components:
- The command-line tool
- Connecting to GitHub
- GitHub credentials
- Deploying Flux
GitOps Kubernetes Deployment Workflow
GitOps uses a version control system (such as Git) to house all information, documentation, and code for a Kubernetes deployment and then uses automated directors to deploy changes to the cluster. It must have been very confusing to understand CI/CD on DevOps, but on Git, it is straightforward.
CI means changes are made on the master branch of Git. CD means Kubernetes updates itself based on changes in the master. The developer changes the code and pushes it to Git, Triggers the build to form the latest docker image, and that image is pushed to the Docker registry. Once the image is uploaded to the repository, this docker image will be replaced in the YAMl file by the config updater service, including all the YAML files pushed. After updating all the YAML files, code and these files are pushed to the Git repository and forwarded to the staging server for review by managers. If the manager seems satisfied with all, he merges code to the main branch and thus deploys it in the production Kubernetes cluster. CICD workflow with GitOps
What are the Benefits of GitOps for Kubernetes?
The benefits of GitOps for Kubernetes are described below:
Improved Security and Compliance
GitOps allows using a single platform for infrastructure change management, reducing downtime and minimizing outages, allowing developers to continue working without compromise.
Faster Deployments
GitOps allows organizations to use open-source technology to perform continuous integrations for fast and reliable deployments. Delivery releases make teams more flexible when responding to customers with minimal delay.
Increased Reliability
Each change can be accounted for using merge requests allowing for rollbacks if new versions don't work. GitOps allows teams to return to the previous state if newer versions experience issues. As a result, teams can implement updated features in stable environments.
What are the Challenges in GitOps for Kubernetes?
The Challenges in GitOps for Kubernetes are below:
CI and CD separation
The CI pipeline handles the building and testing of code and a separate CD pipeline for deployment. Still, the need for GitOps tools to accomplish the separation makes it difficult to implement. The main challenge is conducting tests after deployment, as Operations need visibility into the source code.
Multi Environments Management
GitOps makes it challenging to manage multiple environments. All the environment details are in the Git repository; each time the environment changes, a new Git push has to be executed. When many production environments are involved, creating different branches in Git becomes complicated, and tracking all the branches can be difficult.
Difficult to Rollback
In Git, using a past commit helps for immediate rollbacks in GitOps as the complete history is stored in Git, but multiple past commits can create problems in setting up the rollback process. Different software development teams will have different preferences for performing rollbacks. GitOps does not have a standard practice for rollbacks. Automating rollbacks needs to be better defined.
Hard to Audit
In a large software team, it is good to have a specialized tool on top of the deployment platform; it is tough to answer them by only having access to a Git repository and its history. It refers to the lack of visibility.
Concentrates on automating the software delivery process so that teams can quickly and confidently deploy their code to production. Taken From Article, Kotlin Application Deployment with Kubernetes
Conclusion
GitOps ensures continuous delivery of declarative infrastructure and applications. It provides a set of best practices for deploying, managing, and monitoring containerized clusters and applications. As Git is the central hub for the CICD process, developers can make pull requests to emphasize application and infrastructure deployments to Kubernetes. In an upcoming era, the cloud-native world will quickly adopt GitOps bringing better developer experience and faster feature releases, resulting in improved developer efficiency, a set of tools to maintain visibility across the infrastructure to internal stakeholders, and enhanced collaboration amongst teams is required.
- Read here about Bringing GitOps to ML
- Explore about Application Development on ArgoCD with GitOps
