Project Structure

KubeZero follows a well-defined directory structure that promotes reusability, maintainability, and scalability. Understanding this structure is crucial for effectively using and extending the platform.

Overview

The KubeZero project is organized into layers of abstraction, from low-level reusable components to high-level deployment packages:

kubezero/
├── bootstrap/          # 🚀 One-time setup
├── controller/         # 🎛️ GitOps controllers  
├── modules/           # 🧩 Reusable components
├── stacks/            # 📦 Environment compositions
├── packages/          # 🎁 Complete solutions
└── registry/          # 📋 Runtime state

Architectural Layers

Directory Breakdown

🚀 `bootstrap/` - One-Time Setup

Purpose: Local K3d-based bootstrapper that initializes the entire KubeZero platform.

bootstrap/
├── k3d-bootstrap-cluster.yaml    # K3d cluster configuration
├── kubezero-bootstrap-manifests.yaml  # Initial manifests
├── kustomization.yaml           # Bootstrap composition
└── README.md                    # Bootstrap instructions

Key Characteristics:

Disposable: Used once, then can be deleted
Self-contained: Everything needed to start the platform
Cloud-agnostic: Works on any machine with Docker

Think of it as: The ignition key that starts your entire platform

# Example: bootstrap/k3d-bootstrap-cluster.yaml
apiVersion: k3d.io/v1alpha4
kind: Simple
metadata:
  name: kubezero-bootstrap
servers: 1
agents: 2
ports:
  - port: 80:80
    nodeFilters: [loadbalancer]
  - port: 443:443
    nodeFilters: [loadbalancer]

🎛️ `controller/` - GitOps Controllers

Purpose: Defines ArgoCD applications that manage the GitOps workflow.

controller/
├── kustomization.yaml
├── argo-cd/
│   ├── application.yaml         # ArgoCD self-management
│   └── kustomization.yaml
├── crossplane/
│   ├── application.yaml         # Infrastructure management
│   └── kustomization.yaml
└── namespace/
    └── namespace.yaml           # Required namespaces

Key Characteristics:

Contains only ArgoCD Applications: No actual workload manifests
Points to other directories: References registry/ or stacks/
GitOps entry points: Where the GitOps loop begins

Think of it as: The conductor's baton that orchestrates everything

# Example: controller/argo-cd/application.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: argocd
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/kubezero/kubezero
    targetRevision: HEAD
    path: registry/management
  destination:
    server: https://kubernetes.default.svc
    namespace: argocd

🧩 `modules/` - Reusable Building Blocks

Purpose: Granular, self-contained components that can be used across different environments.

modules/
├── argo-cd/                     # ArgoCD GitOps platform
│   ├── kustomization.yaml
│   ├── namespace.yaml
│   └── values.yaml
├── cert-manager/                # Certificate management
│   ├── kustomization.yaml
│   ├── cluster-issuer.yaml
│   └── values.yaml
├── crossplane/
│   ├── controller/              # Crossplane controller
│   └── providers/               # Cloud provider configs
├── external-dns/                # DNS automation
├── external-secrets/            # Secrets management
├── ingress-nginx/               # Ingress controller
└── vcluster/                    # Virtual clusters

Key Characteristics:

Self-contained: Each module can be deployed independently
Reusable: Used across multiple stacks and environments
Technology-focused: Each module represents a specific technology
No environment specifics: Generic configurations

Think of it as: LEGO blocks that you combine to build your platform

# Example: modules/cert-manager/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - namespace.yaml
  - cluster-issuer.yaml

helmCharts:
  - name: cert-manager
    repo: https://charts.jetstack.io
    version: v1.13.0
    namespace: cert-manager
    valuesFile: values.yaml

📦 `stacks/` - Environment Compositions

Purpose: Combine multiple modules to create environment-specific configurations.

stacks/
├── k8s-essentials/              # Essential platform services
│   └── manifests/
│       └── kustomization.yaml   # References multiple modules
├── virtual-cluster/             # vCluster configuration
│   └── manifests/
│       └── kustomization.yaml
├── eks-cluster/                 # AWS EKS-specific stack
│   └── manifests/
│       └── kustomization.yaml
└── gke-cluster/                 # GCP GKE-specific stack
    └── manifests/
        └── kustomization.yaml

Key Characteristics:

Environment-specific: Tailored for specific deployment scenarios
Aggregates modules: Combines multiple modules with customizations
Contains no raw manifests: Always references modules
Represents logical environments: Like "production platform" or "development setup"

Think of it as: Architectural blueprints that combine LEGO blocks into buildings

# Example: stacks/k8s-essentials/manifests/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../../modules/ingress-nginx
  - ../../../modules/cert-manager
  - ../../../modules/external-dns
  - ../../../modules/external-secrets

patches:
  - target:
      kind: Service
      name: ingress-nginx-controller
    patch: |-
      - op: replace
        path: /spec/type
        value: LoadBalancer

🎁 `packages/` - Complete Solutions

Purpose: High-level bundles that group stacks for specific platforms, customers, or use cases.

packages/
├── README.md
├── aws-management/              # AWS management cluster
│   └── kustomization.yaml       # References AWS-specific stacks
├── aws-worker/                  # AWS worker cluster
│   └── kustomization.yaml
├── gcp-management/              # GCP management cluster
│   └── kustomization.yaml
├── virtual-management/          # Virtual cluster management
│   └── kustomization.yaml
└── virtual-worker/              # Virtual worker setup
    └── kustomization.yaml

Key Characteristics:

Complete solutions: Everything needed for a specific use case
Customer/platform-specific: Tailored for specific scenarios
References stacks: Never contains raw manifests
Deployment units: What you actually deploy to production

Think of it as: Complete building projects that combine multiple blueprints

# Example: packages/aws-management/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../stacks/k8s-essentials/manifests
  - ../../stacks/eks-cluster/manifests

patches:
  - target:
      kind: Deployment
      name: crossplane-provider-aws
    patch: |-
      - op: add
        path: /spec/template/metadata/annotations
        value:
          iam.amazonaws.com/role: arn:aws:iam::123456789:role/crossplane-aws

📋 `registry/` - Runtime GitOps State

Purpose: Reflects what is actually deployed and tracked by ArgoCD in production.

registry/
└── management/                  # Management cluster registry
    ├── _gitops.yaml            # ArgoCD applications list
    └── _kustomization.yaml     # ArgoCD configuration

Key Characteristics:

Runtime state: What's actually running in production
ArgoCD-managed: Automatically updated by GitOps processes
Environment mapping: Maps logical environments to deployments
References only: Points to packages or stacks

Think of it as: The inventory system that tracks what's actually deployed

# Example: registry/management/_gitops.yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: management-platform
  namespace: argocd
spec:
  project: default
  source:
    repoURL: https://github.com/kubezero/kubezero
    targetRevision: HEAD
    path: packages/aws-management
  destination:
    server: https://kubernetes.default.svc
    namespace: default
  syncPolicy:
    automated:
      prune: true
      selfHeal: true

Design Principles

1. 🔄 No Duplication (DRY Principle)

❌ Don't do this:

stacks/management/manifests/argocd/
stacks/production/manifests/argocd/
stacks/staging/manifests/argocd/

✅ Do this instead:

# In each stack's kustomization.yaml
resources:
  - ../../../modules/argo-cd

2. 📚 Layered Abstraction

Each layer builds on the previous one:

Modules → Building blocks
Stacks → Combine modules for environments
Packages → Combine stacks for complete solutions
Registry → Track what's deployed

3. 🎯 Single Responsibility

Each directory has a clear, single purpose:

Bootstrap: Start the platform
Controller: Manage GitOps
Modules: Provide technology components
Stacks: Define environments
Packages: Deliver solutions
Registry: Track deployments

4. 🔌 Loose Coupling

Components can be:

Mixed and matched: Different combinations for different needs
Replaced independently: Swap out modules without affecting others
Extended easily: Add new modules or stacks without changing existing ones

Best Practices

Creating New Modules

# 1. Create module directory
mkdir -p modules/my-new-service

# 2. Add kustomization.yaml
cat > modules/my-new-service/kustomization.yaml <<EOF
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - namespace.yaml
  - deployment.yaml
  - service.yaml

commonLabels:
  app.kubernetes.io/name: my-new-service
  app.kubernetes.io/managed-by: kubezero
EOF

# 3. Add your Kubernetes manifests
# 4. Reference from stacks

Creating New Stacks

# 1. Create stack directory
mkdir -p stacks/my-environment/manifests

# 2. Add kustomization.yaml that references modules
cat > stacks/my-environment/manifests/kustomization.yaml <<EOF
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../../modules/ingress-nginx
  - ../../../modules/my-new-service

patches:
  # Environment-specific customizations
EOF

Creating New Packages

# 1. Create package directory
mkdir -p packages/my-platform

# 2. Add kustomization.yaml that references stacks
cat > packages/my-platform/kustomization.yaml <<EOF
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../stacks/k8s-essentials/manifests
  - ../stacks/my-environment/manifests
EOF

Common Patterns

Module Customization in Stacks

# stacks/production/manifests/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../../modules/cert-manager

patches:
  - target:
      kind: ClusterIssuer
      name: letsencrypt-prod
    patch: |-
      - op: replace
        path: /spec/acme/email
        value: [email protected]

Multi-Environment Stacks

# stacks/multi-env/base/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../../modules/my-app

# stacks/multi-env/overlays/production/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../base

patches:
  - target:
      kind: Deployment
      name: my-app
    patch: |-
      - op: replace
        path: /spec/replicas
        value: 5

Summary Table

Directory	Purpose	Contains	Think of it as
`bootstrap/`	One-time cluster initialization	K3d config + initial manifests	Ignition key
`controller/`	GitOps orchestration	ArgoCD Applications only	Conductor's baton
`modules/`	Reusable technology components	Helm/Kustomize bundles	LEGO blocks
`stacks/`	Environment-specific compositions	Module references + customizations	Blueprints
`packages/`	Complete platform solutions	Stack references + config	Building projects
`registry/`	Runtime deployment state	GitOps application definitions	Inventory system

Next Steps

Components Deep Dive - Learn about individual KubeZero components
Working with Modules - How to create and customize modules
Managing Environments - Environment management best practices

Understanding this structure is key to effectively using and extending KubeZero. Each layer serves a specific purpose and follows clear patterns that make the platform scalable and maintainable.

Overview​

Architectural Layers​

Directory Breakdown​

🚀 bootstrap/ - One-Time Setup​

🎛️ controller/ - GitOps Controllers​

🧩 modules/ - Reusable Building Blocks​

📦 stacks/ - Environment Compositions​

🎁 packages/ - Complete Solutions​

📋 registry/ - Runtime GitOps State​

Design Principles​

1. 🔄 No Duplication (DRY Principle)​

2. 📚 Layered Abstraction​

3. 🎯 Single Responsibility​

4. 🔌 Loose Coupling​

Best Practices​

Creating New Modules​

Creating New Stacks​

Creating New Packages​

Common Patterns​

Module Customization in Stacks​

Multi-Environment Stacks​

Summary Table​

Next Steps​

Overview

Architectural Layers

Directory Breakdown

🚀 `bootstrap/` - One-Time Setup

🎛️ `controller/` - GitOps Controllers

🧩 `modules/` - Reusable Building Blocks

📦 `stacks/` - Environment Compositions

🎁 `packages/` - Complete Solutions

📋 `registry/` - Runtime GitOps State

Design Principles

1. 🔄 No Duplication (DRY Principle)

2. 📚 Layered Abstraction

3. 🎯 Single Responsibility

4. 🔌 Loose Coupling

Best Practices

Creating New Modules

Creating New Stacks

Creating New Packages

Common Patterns

Module Customization in Stacks

Multi-Environment Stacks

Summary Table

Next Steps