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What Is Argo CD?
Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. It was originally developed by Intuit and is now a part of the Cloud Native Computing Foundation (CNCF), where it reached the status of a Graduated project in late 2022. The primary aim of Argo CD is to automate the deployment of applications into specified target environments within Kubernetes, using a Git repository as the source of truth for the desired state of applications.
Argo CD operates by continuously monitoring the Git repository and comparing the desired state of the application defined in the repository with the actual state in the Kubernetes environment. If it detects any discrepancies, it triggers an automatic sync to ensure that the actual state matches the desired state. This way, Argo CD provides a level of automation and control that dramatically simplifies management of deployments in Kubernetes.
A key feature of Argo CD is its comprehensive dashboard which provides visual representations of the application’s status, allowing for easy monitoring and management. It also provides robust access control and audit logs, making it a secure option for managing deployments. Argo CD also supports a wide range of configuration management tools including Kustomize, Helm, Jsonnet and more, providing flexibility in how you define your application’s desired state.
What Is Flux?
Flux is another open source tool, also designed specifically to implement GitOps workflows in Kubernetes. It was developed by Weaveworks, which shut down in early 2024. Like Argo CD, Flux is a CNCF project which has achieved Graduated status. Flux works by continuously pulling changes from Git repositories and applying them to the Kubernetes environment.
Flux’s operation is similar to Argo CD in that it continuously monitors a Git repository to ensure the state of the Kubernetes environment matches the desired state defined in the repository. Any detected discrepancies automatically trigger a sync, bringing the actual state in line with the desired state. Flux also provides automated image updates, automatically tracking and deploying new container images, making it useful for continuous delivery.
Flux also supports a range of configuration management tools, including Helm and Kustomize. Its key features include automated software rollouts, rollback capabilities, and multi-environment support. Flux’s primary interface is a command-line interface. You can also visualize deployments using the open source weave-gitops project.
Argo CD vs Flux: Project History and Evolution
Argo CD was launched by Intuit in 2018, emerging as a solution to simplify Kubernetes deployments using the GitOps approach. It quickly gained traction in the Kubernetes community for its efficient handling of deployment workflows. In 2019, Argo CD became a part of the CNCF (Cloud Native Computing Foundation) as an incubating project, reflecting its growing influence and adoption. In December 2022, it achieved Graduated status.
Over the years, Argo CD has evolved significantly, introducing features like a comprehensive web dashboard, robust access controls, and integrations with various configuration management tools. Its development has been marked by a focus on usability, security, and extensibility, catering to a wide range of deployment requirements. It is used by some of the world’s biggest technology companies, including Google, NVIDIA, Tesla, and Red Hat.
Flux was developed by Weaveworks and introduced in 2016. It was one of the pioneering projects to implement GitOps principles for Kubernetes. Flux’s initial focus was on simplifying the continuous delivery pipeline, automating the application of changes from Git repositories to Kubernetes. In 2020, Flux joined the CNCF, and achieved Graduated status in November 2023. Flux v2, released in late 2020, brought significant improvements, including a more modular design, better support for Helm, and a shift to a reconciliation-based operation model.
However, in February 2024, the future of Flux was put in question, with the shut down of Weaveworks, its main corporate sponsor. Although FluxCD is open-source and backed by the CNCF, a lack of dedicated resources and active maintainers may slow down new feature development and maintenance. In addition, due to the uncertainty around future updates and improvements, organizations relying on Flux might face risks related to security vulnerabilities, compatibility issues with new Kubernetes releases, and a decline in community support.
Argo CD vs Flux: Key Differences
1. Synchronization
Both Argo CD and Flux are designed to ensure that the desired state in the Git repository matches the actual state in the Kubernetes environment. However, they handle synchronization differently.
Notable differences are that the sync interval is global in Argo CD, while it can be defined per application in Flux. ArgoCD can optionally perform a diff instead of a full synchronization, while Flux always discards local changes and applies what is in Git. Lastly, Flux can temporarily pause syncs, while Argo CD cannot.
2. Architecture
Argo CD and Flux differ significantly in their architectural approaches. Argo CD is a standalone application with a built-in UI and comprehensive dashboard, which provides a holistic view of the application states and deployments. It also offers a robust API for integrations.
Flux is designed as a set of controllers that run within Kubernetes, relying heavily on Kubernetes-native resources and APIs. This modular approach allows for more granular control and flexibility but requires additional setup for a complete overview, often involving external tools like Weave GitOps for visualization.
3. ApplicationSets
Argo CD’s ApplicationSets feature provides advanced capabilities for managing multiple applications at scale. This feature enables users to create and manage multiple Argo CD applications from a single ApplicationSet, making it easier to handle complex deployments across multiple environments.
Flux does not have an equivalent built-in feature. Instead, it leverages its native support for Helm and Kustomize to manage complex deployments, often requiring additional scripting and tooling to achieve similar functionality.
4. Sync Windows
Argo CD has a Sync Windows feature, which is not supported by Flux. Sync windows are windows of time where synchronizations will either be blocked or allowed. They are defined by a kind, which can be either allow or deny, a cron-based schedule, a duration, and a relation to applications, namespaces and clusters.
Sync Windows typically operate automatically, but allow an override for manual syncs, which makes it possible to prevent an automated sync or override a window for operational reasons.
5. Web UI
Argo CD has a comprehensive web UI that allows users to visualize application states, manage deployments, and access detailed logs. This UI-centric design enhances user experience, making it easier for teams to monitor and manage applications without deep command-line expertise.
Flux is primarily CLI-based and does not have an official web UI. Users who require visualization typically turn to Weave GitOps, an additional layer built on top of Flux, which offers a UI for deployment management, but is quite limited compared to the Argo CD UI.
6. RBAC
Argo CD implements its own RBAC system independent of Kubernetes, providing granular control over user permissions within the Argo CD environment. This setup can integrate with external identity providers via OIDC.
Flux relies on Kubernetes-native RBAC, adhering to the least privilege principle for its service accounts. This approach ensures tight integration with Kubernetes security policies but lacks the granularity offered by Argo CD.
7. Installation
Argo CD’s installation involves deploying its components via YAML manifests, with configuration left to the user, making it less opinionated and more flexible in setup. Flux provides a streamlined installation process that includes bootstrapping, where it creates a repository, populates it with manifests, and configures the system to manage syncing automatically. This makes Flux easier to get started with for users new to GitOps.
Argo CD vs. Flux: How to Choose?
When deciding between Argo CD and Flux, consider the following key factors:
| Criteria | ArgoCD | Flux |
| Synchronization | Global sync interval. Can optionally just diff. Supports flexible Sync Windows. | Per app sync interval. Always discards cluster changes. No support for Sync windows |
| Architecture | Standalone application with built-in UI | Modular set of controllers within Kubernetes |
| Application Management | Supports ApplicationSets for managing multiple apps | Utilizes Helm and Kustomize, requires extra tooling |
| Web UI | Comprehensive and user-friendly | Primarily CLI-based; limited visualization via Weave GitOps |
| RBAC | Custom RBAC system with granular controls | Relies on Kubernetes-native RBAC |
| Installation | Flexible, YAML-based configuration | Streamlined with automated bootstrapping |
| Corporate support and community | Strong community and corporate backing | Uncertain future post-Weaveworks shutdown |
Here are a few key considerations when making the choice between Argo CD and Flux:
- User interface: Teams preferring a visual interface should lean towards Argo CD for its robust web UI.
- Scalability and complexity: For managing complex deployments, Argo CD’s ApplicationSets provide a streamlined approach, whereas Flux requires additional scripting.
- Security requirements: If granular control over permissions is critical, Argo CD’s custom RBAC offers more flexibility.
- Ease of setup: Beginners might find Flux easier to start with due to its automated bootstrapping.
- Future stability: Consider the potential impact of Weaveworks’ shutdown on Flux’s future updates and community support.
Related content: Read our guide to Argo Kubernetes
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