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Cloud-Init Documentation

File: docs/hosts-cloud-init-readme.md Purpose: Cloud-init configuration and templates for automated host provisioning Target Audience: Infrastructure engineers working with cloud-init deployments Last Updated: September 22, 2024

📋 Overview​

Cloud-init is a critical component for automated host provisioning across different environments in the Urbalurba infrastructure. It provides a standardized way to configure hosts during their initial boot process, ensuring consistent setup across various deployment scenarios. In addition to basic system configuration, cloud-init also handles:

  • Connection to the Tailscale network for secure remote management
  • Standardized Kubernetes (MicroK8s) installation and configuration
  • Consistent security hardening across all environments

This ensures that all hosts, regardless of their deployment environment, are:

  • Securely accessible for management
  • Properly configured for their intended role
  • Integrated into the infrastructure's network
  • Ready for service deployment

🔑 Prerequisites​

IMPORTANT: Before using cloud-init templates, you must set up SSH keys for Ansible authentication:

👉 SSH Key Setup Guide - Create the required SSH keys for cloud-init deployments

The SSH keys created in this prerequisite step are essential for:

  • Ansible automation and host management
  • Secure SSH access to provisioned hosts
  • Cloud-init user authentication setup

Cloud-Init Templates​

Located in cloud-init/:

  • azure-cloud-init-template.yml - Azure VM configuration
  • gcp-cloud-init-template.yml - Google Cloud Platform configuration
  • oci-cloud-init-template.yml - Oracle Cloud Infrastructure configuration
  • multipass-cloud-init-template.yml - Multipass VM configuration
  • raspberry-cloud-init-template.yml - Raspberry Pi configuration
  • provision-cloud-init-template.yml - Generic provisioning configuration

Cloud-Init Generation​

The create-cloud-init.sh script generates cloud-init configurations by:

  1. Reading template files
  2. Extracting secrets from Kubernetes secrets file
  3. Replacing placeholders with actual values
  4. Generating environment-specific cloud-init files

Usage​

./create-cloud-init.sh <hostname> <template-name>

Where:

  • hostname: The name of the host to be configured
  • template-name: The name of the cloud-init template to use (e.g., azure, gcp, multipass)

Common Cloud-Init Features​

All cloud-init configurations include:

1. System Configuration​

  • Hostname setting
  • Timezone configuration
  • System updates
  • Package management

2. User Management​

  • Ansible user creation
  • SSH key configuration
  • Sudo privileges
  • User groups

3. Security Setup​

  • SSH hardening
  • Firewall configuration
  • Security updates
  • Access control

4. Kubernetes Setup​

  • MicroK8s installation
  • Cluster configuration
  • Network plugin setup
  • Storage configuration

5. Network Configuration​

  • Tailscale VPN setup
  • Network interface configuration
  • DNS settings
  • Proxy configuration (if needed)

6. Environment Setup​

  • Path configuration
  • Environment variables
  • System limits
  • Resource allocation

Template Structure​

Each cloud-init template follows a standard structure:

#cloud-config
users:
  - name: ansible
    # User configuration

write_files:
  # System configuration files

package_update: true
package_upgrade: true
packages:
  # Required packages

runcmd:
  # Post-installation commands