5.3.2. Cloud Platforms and Hybrid Infrastructure

Cloud Concepts for XK0-006:

The exam tests cloud-aware Linux administration, not deep AWS/Azure/GCP expertise. Key concepts:

# cloud-init — configures a new VM on first boot
# /etc/cloud/cloud.cfg — configuration
# /var/log/cloud-init.log — initialization log
# Status check
cloud-init status               # show status of initialization

# Instance metadata (AWS example)
curl http://169.254.169.254/latest/meta-data/instance-id
curl http://169.254.169.254/latest/meta-data/public-ipv4

Terraform — Infrastructure Provisioning:

# main.tf — declarative infrastructure
provider "aws" {
  region = "us-east-1"
}

resource "aws_instance" "web" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"
  key_name      = "my-key"

  tags = {
    Name = "webserver"
    Env  = "production"
  }
}

terraform init                 # Initialize providers
terraform plan                 # Preview changes
terraform apply                # Apply changes
terraform destroy              # Tear down infrastructure

Terraform vs. Ansible:

⚠️ Exam Trap: Cloud-init user data scripts run once at first boot, not on every reboot. If you need to reconfigure a VM, you cannot rely on user data — you need Ansible, Puppet, or manual intervention. Also, the metadata endpoint 169.254.169.254 is a link-local address reachable only from within the instance — it's not a general network address.

Reflection Question: You provision a cloud VM using Terraform and configure it with an Ansible playbook. Two weeks later, a developer manually edits /etc/nginx/nginx.conf on the VM. How does each tool handle this configuration drift, and what would you run to restore the desired state?