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Kustomize Cheatsheet

Installazione

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Comandi di base

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ConfigMap e gestione segreta

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Image Management

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Uso avanzato

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Configurazione

Kustomization Basic. Ciao. Struttura

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

# Resources to include
resources:
  - deployment.yaml
  - service.yaml
  - configmap.yaml

# Namespace for all resources
namespace: production

# Common labels applied to all resources
commonLabels:
  app: myapp
  environment: prod

# Common annotations applied to all resources
commonAnnotations:
  managed-by: kustomize
  version: "1.0.0"

# Name prefix/suffix
namePrefix: prod-
nameSuffix: -v1

# Images to replace
images:
  - name: myapp
    newName: gcr.io/myproject/myapp
    newTag: v2.0.0

# Replica counts
replicas:
  - name: myapp-deployment
    count: 3

Overlay Structure with Base

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

# Reference to base
bases:
  - ../../base

# Production-specific namespace
namespace: production

# Production-specific patches
patchesStrategicMerge:
  - deployment-patch.yaml
  - service-patch.yaml

# Production replicas
replicas:
  - name: myapp
    count: 5

# Production images
images:
  - name: myapp
    newTag: v2.0.0

Strategic Merge Patch Esempio

# deployment-patch.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
        - name: myapp
          resources:
            limits:
              memory: "2Gi"
              cpu: "1000m"
            requests:
              memory: "1Gi"
              cpu: "500m"
          env:
            - name: ENVIRONMENT
              value: "production"

JSON Patch Esempio

# kustomization.yaml with JSON patches
patchesJson6902:
  - target:
      group: apps
      version: v1
      kind: Deployment
      name: myapp
    patch: |-
      - op: replace
        path: /spec/replicas
        value: 5
      - op: add
        path: /spec/template/spec/containers/0/env/-
        value:
          name: NEW_VAR
          value: "new_value"

ConfigMap Generator

configMapGenerator:
  - name: app-config
    files:
      - application.properties
      - config.json
    literals:
      - ENVIRONMENT=production
      - LOG_LEVEL=info
    behavior: create  # create, replace, or merge
    options:
      disableNameSuffixHash: false
      labels:
        app: myapp
      annotations:
        config-version: "1.0"

Secret Generator

secretGenerator:
  - name: db-credentials
    literals:
      - username=admin
      - password=secretpassword
    type: Opaque
  - name: tls-secret
    files:
      - tls.crt=cert.pem
      - tls.key=key.pem
    type: kubernetes.io/tls

Sostituzioni (sostituzioni variabili)

replacements:
  - source:
      kind: ConfigMap
      name: app-config
      fieldPath: data.app_version
    targets:
      - select:
          kind: Deployment
        fieldPaths:
          - spec.template.metadata.labels.version
      - select:
          kind: Service
        fieldPaths:
          - metadata.annotations.[app.version]

Components (Configurazione riutilizzabile)

# components/monitoring/kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1alpha1
kind: Component

resources:
  - servicemonitor.yaml
  - prometheusrule.yaml

labels:
  - pairs:
      monitoring: enabled

# Using component in overlay
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

resources:
  - ../../base

components:
  - ../../components/monitoring
  - ../../components/logging

Common Use Cases

Use Case 1: Multi-Environment Deployment

# Directory structure
# .
# ├── base/
# │   ├── kustomization.yaml
# │   ├── deployment.yaml
# │   └── service.yaml
# ├── overlays/
# │   ├── dev/
# │   │   └── kustomization.yaml
# │   ├── staging/
# │   │   └── kustomization.yaml
# │   └── production/
# │       └── kustomization.yaml

# Create base
cd base
kustomize create --autodetect
kustomize edit add label app:myapp

# Create dev overlay
cd ../overlays/dev
kustomize create
kustomize edit add base ../../base
kustomize edit set namespace dev
kustomize edit set replicas deployment/myapp=1
kustomize edit set image myapp=myapp:dev

# Create production overlay
cd ../production
kustomize create
kustomize edit add base ../../base
kustomize edit set namespace production
kustomize edit set replicas deployment/myapp=5
kustomize edit set image myapp=myapp:v1.0.0

# Deploy to different environments
kubectl apply -k overlays/dev
kubectl apply -k overlays/staging
kubectl apply -k overlays/production

Use Case 2: Aggiungere segreti e conflitti

# Create base configuration
kustomize create --resources deployment.yaml,service.yaml

# Add ConfigMap from file
kustomize edit add configmap app-config \
  --from-file=application.properties \
  --from-literal=LOG_LEVEL=info

# Add Secret from literals
kustomize edit add secret db-credentials \
  --from-literal=username=admin \
  --from-literal=password=changeme

# Add Secret from files
kustomize edit add secret tls-certs \
  --from-file=tls.crt=./certs/server.crt \
  --from-file=tls.key=./certs/server.key

# Build and verify
kustomize build . | grep -A 10 "kind: ConfigMap"
kustomize build . | grep -A 10 "kind: Secret"

# Apply to cluster
kubectl apply -k .

Use Case 3: Patching Resources for Different Environments

# Create production overlay
mkdir -p overlays/production
cd overlays/production

# Create kustomization
kustomize create
kustomize edit add base ../../base
kustomize edit set namespace production

# Create patch file for resource limits
cat <<EOF > deployment-patch.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
        - name: myapp
          resources:
            limits:
              memory: "4Gi"
              cpu: "2000m"
            requests:
              memory: "2Gi"
              cpu: "1000m"
EOF

# Add patch to kustomization
kustomize edit add patch --path deployment-patch.yaml

# Add production-specific environment variables
cat <<EOF > env-patch.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp
spec:
  template:
    spec:
      containers:
        - name: myapp
          env:
            - name: ENVIRONMENT
              value: "production"
            - name: DB_HOST
              value: "prod-db.example.com"
EOF

kustomize edit add patch --path env-patch.yaml

# Build and apply
kustomize build . | kubectl apply -f -

Use Case 4: Utilizzo di componenti per funzioni opzionali

# Create monitoring component
mkdir -p components/monitoring
cd components/monitoring

# Create component kustomization
cat <<EOF > kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1alpha1
kind: Component

resources:
  - servicemonitor.yaml

labels:
  - pairs:
      monitoring.enabled: "true"
EOF

# Create ServiceMonitor resource
cat <<EOF > servicemonitor.yaml
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: myapp
spec:
  selector:
    matchLabels:
      app: myapp
  endpoints:
    - port: metrics
      interval: 30s
EOF

# Use component in production overlay
cd ../../overlays/production
kustomize edit add component ../../components/monitoring

# Build with monitoring enabled
kustomize build .

# Deploy
kubectl apply -k .

Use Case 5: Gestione delle applicazioni multiple

# Directory structure for multiple apps
# .
# ├── apps/
# │   ├── frontend/
# │   │   ├── base/
# │   │   └── overlays/
# │   ├── backend/
# │   │   ├── base/
# │   │   └── overlays/
# │   └── database/
# │       ├── base/
# │       └── overlays/
# └── clusters/
#     ├── dev/
#     └── production/

# Create cluster-level kustomization for production
cd clusters/production
cat <<EOF > kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

namespace: production

resources:
  - ../../apps/frontend/overlays/production
  - ../../apps/backend/overlays/production
  - ../../apps/database/overlays/production

commonLabels:
  environment: production
  cluster: production-us-east-1
EOF

# Deploy entire production cluster
kubectl apply -k clusters/production

# Deploy only frontend
kubectl apply -k apps/frontend/overlays/production

# Build and review all production resources
kustomize build clusters/production > production-manifests.yaml

Migliori Pratiche

• ** Utilizzare la base e sovrapposizioni modello**: Mantenere configurazioni comuni in base e cambiamenti specifici per l'ambiente in sovrapposizioni per seguire i principi DRY e mantenere la coerenza in ambienti

• Abilitare il suffisso del nome per ConfigMaps/Secrets: Questo trigger pod riavvia quando la configurazione cambia, assicurando che le applicazioni prelevano automaticamente nuove configurazioni (INLINE_CODE_63_)

• Organizzare la struttura della directory logicamente: Utilizzare una gerarchia chiara come base/, overlays/dev/, overlays/production/, e components/ per rendere il repository facile da navigare e capire

• Utilizzare le patch strategiche per semplici modifiche: Preferire patchesStrategicMerge su patch JSON per la leggibilità e la manutenbilità quando si effettuano modifiche semplici alle risorse

• Controllo delle vibrazioni. Commettere tutti i file di kustomization, patch e si manifesta a Git per la tracciabilità completa, capacità di rollback e flussi di lavoro GitOps

• Validate prima di applicare Eseguire sempre kustomize build . | kubectl apply --dry-run=server -f - per catturare gli errori e convalidare le risorse dallo schema OpenAPI del cluster prima dell'implementazione effettiva

• Utilizza componenti per caratteristiche facoltative: Crea componenti riutilizzabili per problemi di taglio incrociato come monitoraggio, registrazione o politiche di sicurezza che possono essere eventualmente incluse in diversi sovrapposizioni

• Keep patch concentrati e minimi: Creare piccole patch mirate che modificano solo ciò che è necessario piuttosto che duplicare intere definizioni delle risorse

• ** Utilizzare sostituzioni al posto dei vars**: Preferire il nuovo campo replacements_ sopra deprecato vars per sostituzioni variabili e riferimenti cross-resource

• ** Documenta la tua struttura di kustomization**: Aggiungi commenti in kustomization. file yaml e mantenere un README spiegando la strategia di sovrapposizione e come distribuire in ambienti diversi

Risoluzione dei problemi

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Quick Reference Tips:

• Usa kubectl apply -k . invece di kustomize build . | kubectl apply -f - per implementazioni più semplici
• Aggiungi --dry-run=client -o yaml per visualizzare in anteprima le modifiche senza accesso a cluster
• Usa kustomize cfg tree per visualizzare le relazioni e le dipendenze delle risorse
• Set KUSTOMIZE_PLUGIN_HOME variabili di ambiente per posizioni di plugin personalizzate
• Controllare la documentazione del trasformatore incorporato: ______________