Added Vagrant doc

Vagrant/Vagrantfile.md

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+
+# **Vagrant Configuration Reference for DevOps Engineers**
+
+This document provides a practical collection of Vagrant configurations commonly used in DevOps workflows. Each example includes explanations and recommended usage patterns.
+
+---
+
+# **1. Basic Ubuntu VM**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/focal64"
+
+  config.vm.network "private_network", ip: "192.168.56.10"
+
+  config.vm.provider "virtualbox" do |vb|
+    vb.memory = "1024"
+    vb.cpus = 1
+  end
+end
+```
+
+### **Summary**
+
+* Defines a simple Ubuntu VM.
+* Adds private network access.
+* Sets CPU and memory limits for VirtualBox.
+
+---
+
+# **2. VM with Shell Provisioning**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/jammy64"
+
+  config.vm.provision "shell", inline: <<-SHELL
+    apt update
+    apt install -y nginx
+    systemctl enable nginx
+  SHELL
+end
+```
+
+### **Summary**
+
+* Runs a shell script automatically on VM boot.
+* Installs and enables Nginx.
+
+---
+
+# **3. Multi-Machine Environment (Web + Database)**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+
+  config.vm.define "web" do |web|
+    web.vm.box = "ubuntu/focal64"
+    web.vm.hostname = "web"
+    web.vm.network "private_network", ip: "192.168.56.11"
+
+    web.vm.provision "shell", inline: <<-SHELL
+      apt update
+      apt install -y apache2
+    SHELL
+  end
+
+  config.vm.define "db" do |db|
+    db.vm.box = "ubuntu/focal64"
+    db.vm.hostname = "db"
+    db.vm.network "private_network", ip: "192.168.56.12"
+
+    db.vm.provision "shell", inline: <<-SHELL
+      apt update
+      apt install -y mysql-server
+    SHELL
+  end
+
+end
+```
+
+### **Summary**
+
+* Creates two VMs.
+* Web VM runs Apache.
+* DB VM runs MySQL.
+* Local network enables app-to-database communication.
+
+---
+
+# **4. Using Ansible for Provisioning**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/focal64"
+
+  config.vm.provision "ansible" do |ansible|
+    ansible.playbook = "playbook.yml"
+    ansible.inventory_path = "hosts"
+  end
+end
+```
+
+### **Summary**
+
+* Leverages Ansible for idempotent provisioning.
+* Requires a playbook and inventory file.
+
+---
+
+# **5. Docker Provider Example**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.provider "docker" do |d|
+    d.image = "nginx:latest"
+    d.remains_running = true
+    d.ports = ["8080:80"]
+  end
+end
+```
+
+### **Summary**
+
+* Uses Docker engine instead of a VM.
+* Runs Nginx container accessible on host port 8080.
+
+---
+
+# **6. Synced Folder Example**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/focal64"
+
+  config.vm.synced_folder "./app", "/var/www/app", type: "virtualbox"
+
+  config.vm.provision "shell", inline: <<-SHELL
+    apt update
+    apt install -y nodejs npm
+  SHELL
+end
+```
+
+### **Summary**
+
+* Syncs host source code into VM.
+* Suitable for development environments where code updates must sync immediately.
+
+---
+
+# **7. Kubernetes Single-Node Cluster (kubeadm)**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/focal64"
+  config.vm.hostname = "k8s-master"
+
+  config.vm.provider "virtualbox" do |vb|
+    vb.cpus = 2
+    vb.memory = 4096
+  end
+
+  config.vm.provision "shell", path: "install-k8s.sh"
+end
+```
+
+### **Summary**
+
+* Boots a VM with enough resources for Kubernetes.
+* Runs external script containing Kubernetes installation steps.
+
+---
+
+# **8. Port Forwarding with Multiple Shell Provisioners and VirtualBox Limits**
+
+### **Vagrantfile**
+
+```ruby
+Vagrant.configure("2") do |config|
+  config.vm.box = "ubuntu/focal64"
+  config.vm.hostname = "webserver"
+
+  # Port forwarding (host 8080 → guest 80)
+  config.vm.network "forwarded_port", guest: 80, host: 8080
+
+  # VirtualBox hardware limits
+  config.vm.provider "virtualbox" do |vb|
+    vb.memory = "2048"
+    vb.cpus = 2
+  end
+
+  # Provisioner 1: package install
+  config.vm.provision "shell", inline: <<-SHELL
+    apt update
+    apt install -y nginx curl
+  SHELL
+
+  # Provisioner 2: configuration and service restart
+  config.vm.provision "shell", inline: <<-SHELL
+    echo "Hello from Vagrant" > /var/www/html/index.html
+    systemctl restart nginx
+  SHELL
+end
+```
+
+### **Summary**
+
+* Demonstrates forwarded ports for local development.
+* Runs two shell provisioners in sequence.
+* Applies VirtualBox memory and CPU constraints.
+
+---
+
+# **Additional Recommendations**
+
+### **General Best Practices**
+
+* Use `config.ssh.insert_key = false` for shared team environments.
+* Install recommended plugins:
+
+  * vagrant-vbguest
+  * vagrant-hostmanager
+* Pin specific box versions for reproducibility.
+* Store provisioning scripts in separate files for maintainability.
+
+### **Resource Allocation Guidelines**
+
+* Web servers: 1–2 GB RAM, 1–2 CPUs
+* Kubernetes nodes: 4 GB+ RAM, 2 CPUs+
+* Database nodes: 2–4 GB RAM minimum