Declarative Object Configs

Declarative config means you describe the desired state in files and manage everything through kubectl apply.

Why it works

• Changes are reviewable in git
• Rollbacks are simple by reapplying history
• Reapplying the same file is safe

Multi-object example

apiVersion: v1
kind: Namespace
metadata:
  name: demo
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: api
  namespace: demo
spec:
  replicas: 2
  selector:
    matchLabels:
      app: api
  template:
    metadata:
      labels:
        app: api
    spec:
      containers:
        - name: api
          image: nginx:1.25

Common flow

kubectl apply -f app.yaml
kubectl diff -f app.yaml
kubectl delete -f app.yaml

Tips

• Standardize labels and selectors
• Run kubectl diff before apply

Practical notes

• Start with a quick inventory: kubectl get nodes, kubectl get pods -A, and kubectl get events -A.
• Compare desired vs. observed state; kubectl describe usually explains drift or failed controllers.
• Keep names, labels, and selectors consistent so Services and controllers can find Pods.

Quick checklist

• The resource matches the intent you described in YAML.
• Namespaces, RBAC, and images are correct for the target environment.
• Health checks and logs are in place before promotion.

References

• Declarative Management
• Kubernetes Objects
• kubectl apply