GitOps Workflows with Flux and Kustomize

GitOps is a set of practices that combines Git version control with Kubernetes cluster management to automate and streamline the deployment of applications. Two popular tools for implementing GitOps workflows are Flux and Kustomize. This article will delve into the technical details of using Flux and Kustomize to manage Kubernetes clusters efficiently.

Flux: A GitOps Tool

Flux is a GitOps tool designed to automate the deployment of Kubernetes resources. It works by continuously monitoring a Git repository for changes and applying those changes to the cluster. This ensures that the cluster state is always in sync with the desired state defined in the Git repository.

Kustomize: A Configuration Management Tool

Kustomize is a configuration management tool that allows users to define and manage Kubernetes resources using a declarative configuration file. It provides a flexible way to customize and generate Kubernetes configurations based on a set of base configurations.

Integrating Flux and Kustomize

To integrate Flux and Kustomize, you can use Flux to manage the deployment of Kustomize configurations. This involves creating a Git repository that contains the Kustomize configuration files and then configuring Flux to monitor this repository for changes.

Here is an example of how you can use Flux to deploy a Kustomize configuration:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
metadata:
  name: example
spec:
  configMapGenerator:
  - name: example-config
    literals:
    - FOO=bar
  configMapGenerator:
  - name: example-config-2
    literals:
    - BAR=baz

In this example, the Kustomize configuration defines two config maps, example-config and example-config-2, with specific literals. Flux can then be configured to deploy this configuration to a Kubernetes cluster.

Flux Configuration

To configure Flux to deploy the Kustomize configuration, you need to create a Flux configuration file that specifies the Git repository and the Kustomize configuration to deploy. Here is an example of a Flux configuration file:

apiVersion: flux.weave.works/v1alpha1
kind: GitRepository
metadata:
  name: example
spec:
  url: https://github.com/example/example.git
  ref:
    branch: main
  interval: 1m

---
apiVersion: flux.weave.works/v1alpha1
kind: Kustomization
metadata:
  name: example
spec:
  interval: 1m
  path: ./kustomize
  prune: true
  sourceRef:
    kind: GitRepository
    name: example

In this example, the Flux configuration specifies a Git repository with a URL and a branch to monitor. It also specifies a Kustomization resource that points to the Kustomize configuration file in the Git repository.

Workflow Example

Here is an example of a complete workflow using Flux and Kustomize:

1. Create a Git Repository: Create a Git repository that contains the Kustomize configuration files.

2. Configure Flux: Configure Flux to monitor the Git repository for changes and deploy the Kustomize configuration to a Kubernetes cluster.

3. Make Changes to the Configuration: Make changes to the Kustomize configuration files in the Git repository.

4. Flux Deploys the Changes: Flux detects the changes and deploys the updated Kustomize configuration to the Kubernetes cluster.

Conclusion

In conclusion, Flux and Kustomize provide a powerful combination for managing Kubernetes clusters using GitOps workflows. By integrating these tools, you can automate the deployment of Kubernetes resources and ensure that your cluster state is always in sync with the desired state defined in your Git repository.

Platform engineering is the discipline of designing and building toolchains and workflows that enable self-service capabilities for software engineering organizations in the cloud-native era. The use of Flux and Kustomize in GitOps workflows is an example of platform engineering in action, as it provides an integrated product that covers the operational necessities of the entire lifecycle of an application.