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Containerization & Orchestration/Kubernetes/workloads/04-Deployment.md

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+# 🚀 Kubernetes Deployment Management
+
+A guide to managing **Deployments** in Kubernetes, including listing, editing, scaling, rollbacks, and version history.
+
+---
+
+## 📋 Listing & Editing Deployments
+
+### 🔹 List Deployments in a Namespace
+
+```bash
+kubectl get deploy -n <namespace>
+```
+
+### 🔹 Edit a Deployment
+
+```bash
+kubectl edit deployment.apps -n <namespace> <deployment-name>
+```
+
+> 🛠️ **Note:**
+> Unlike ReplicaSets, Deployments **automatically update** existing Pods when the image or spec is changed. This makes Deployments ideal for rolling updates and version control.
+
+---
+
+## 📈 Scaling a Deployment
+
+Scale the number of replicas (Pods) for a Deployment:
+
+```bash
+kubectl scale -n <namespace> deployment <deployment-name> --replicas=<number>
+```
+
+---
+
+## 🔁 Rollout Management
+
+### 🔹 View Rollout History
+
+```bash
+kubectl rollout history deployment -n <namespace> <deployment-name>
+```
+
+### 🔹 View Specific Revision
+
+```bash
+kubectl rollout history deployment -n <namespace> <deployment-name> --revision=<revision-number>
+```
+
+### 🔹 Roll Back to a Previous Revision
+
+```bash
+kubectl rollout undo deployment -n <namespace> <deployment-name> --to-revision=<revision-number>
+```
+
+> ✅ **Tip:**
+> Deployments maintain revision history. This allows you to **roll back to a previous working version** in case of failure.
+
+---
+
+## 🧾 Example Deployment YAML
+
+```yaml
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: app-1
+  namespace: dev
+  labels:
+    label1: test1
+    app.kubernetes.io/label2: test2
+spec:
+  replicas: 3
+  selector:
+    matchLabels:
+      app.kubernetes.io/label2: test2
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/label2: test2
+        os: linux
+    spec:
+      containers:
+        - name: nginx
+          image: nginx
+```
+
+> 🎯 **Why use Deployments?**
+> They offer:
+
+* Rolling updates
+* Rollbacks
+* Declarative Pod management
+* History tracking
+
+---
+
+## ✅ Summary
+
+| Feature          | Pod | ReplicaSet | Deployment |
+| ---------------- | --- | ---------- | ---------- |
+| Manual creation  | ✅   | 🚫         | 🚫         |
+| Scales Pods      | ❌   | ✅          | ✅          |
+| Self-healing     | ❌   | ✅          | ✅          |
+| Rolling updates  | ❌   | ❌          | ✅          |
+| Revision history | ❌   | ❌          | ✅          |
+