Challenges with CD into Kubernetes?
Tools installation and management: Requires installing and managing tools like "Kubectl" and "Helm."
Accessing Kubernetes Clusters: Configuring access management and sharing credentials for authorization to Kubernetes clusters.
Security & Operational Challenges: Increasing configurations and operational overhead, along with security risks when sharing cluster credentials.
Issues while scaling infrastructure: Reconfiguration needed for each new cluster, adding complexity when scaling Kubernetes infrastructure.
Lack of Visibility: Limited visibility into deployments without GitOps or Kubernetes-native CI/CD pipelines, leading to unclear status and dependency on incident reports.
These challenges impact operational efficiency, security, scalability, and visibility in CD workflows on Kubernetes.
What is GitOps?
GitOps is a software development methodology and operational model that leverages Git as the single source of truth for managing and controlling the entire application lifecycle. It combines the practices of version control and declarative infrastructure to enable automated, auditable, and reliable application deployments and operations.
In GitOps, the desired state of the entire system, including application code, configurations, and infrastructure definitions, is stored in a Git repository. The repository serves as a source of truth, capturing all changes and revisions over time.
What is Argo CD?
Argo CD is an open-source continuous delivery and GitOps tool specifically designed for deploying and managing applications on Kubernetes clusters. It follows a declarative approach, where the desired state of applications is defined in Git repositories using YAML manifests. Argo CD continuously monitors these repositories, compares the desired state with the actual state in the cluster, and automatically reconciles any differences.
Advantages of Argo CD
Application Management: Argo CD allows you to define and manage applications using YAML manifests. It provides a simple and intuitive way to specify the application source, target namespace, synchronization settings, and other parameters.
Continuous Synchronization: Argo CD constantly synchronizes the state of applications with their desired state in the Git repositories. It detects changes in the repositories and applies them to the cluster, ensuring that the deployed applications remain in sync with the defined configuration.
Rollouts and Rollbacks: Argo CD supports controlled rollouts and rollbacks of application updates. It allows you to define rollout strategies, such as Blue/Green or Canary deployments, to ensure smooth transitions between different versions of the application. In case of issues, you can easily roll back to a previous known-good state.
Multi-Environment Support: Argo CD facilitates managing applications across multiple environments, such as development, staging, and production. It enables you to define different sets of configurations and deployment policies for each environment, ensuring consistency and isolation.
Multi-Cluster Management: Argo CD can manage applications across multiple Kubernetes clusters. It provides a centralized control plane to deploy and synchronize applications across different clusters, simplifying the management of complex distributed systems.
GitOps Principles: Argo CD embraces the GitOps methodology, which involves using Git as a single source of truth for defining the desired state of applications. It leverages Git's version control capabilities, allowing you to track changes, audit configurations, and collaborate effectively.
Web UI and CLI: Argo CD offers a web-based user interface (UI) that provides a graphical representation of applications and their synchronization status. It also provides a command-line interface (CLI) for automation and scripting purposes, enabling programmatic interactions with Argo CD.
How does Argo CD work?
A developer makes changes to an application, and pushes a new version to a Git repo, along with a revised configuration for the Kubernetes resource definitions.
A continuous integration pipeline is triggered, which results in a new container image being pushed to a registry.
Once the pull request has been reviewed and the changes merged to the main branch, a webhook is triggered which notifies ArgoCD of new changes. ArgoCD clones the repo, compares the desired state of the application with the actual state running in the cluster, and applies the changes.
At this point, Kubernetes takes over to reconcile the workload. The tracked repo might hold the config for an application that runs in the same cluster as ArgoCD, but ArgoCD can also manage applications running in remote clusters. The workflow effectively installs or upgrades an application without a human interacting directly with the cluster.
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