Linux Templates¶

This section demonstrates Linux-based virtual machine templates and configurations using Fleet Manager application manifests. These examples show how to create, configure, and deploy Linux VMs for various use cases.

Overview¶

These Linux templates provide:

Base images for rapid VM deployment
Template VMs in shutoff state for cloning
Cloud-init integration for automated setup
Package management and service configuration
Multi-distribution support (Ubuntu, CentOS, Fedora)

Linux Template VM¶

This example creates a Linux template VM that can be cloned for production use.

Template Configuration¶

linux-template.yaml

type: Application
version: "1.0.0"
metadata:
  name: "linux-template"
  labels:
    - "type:template"
    - "os:linux"
    - "distro:fedora"
spec:
  assets:
    - name: "fedora-base"
      type: "virtual_disk"
      format: "raw"
      url: "https://your-fedora-base-image-url.img"

  resources:
    - type: "virdomain"
      name: "linux-template"
      spec:
        description: "Fedora-based Linux template for cloning"
        cpu: 2
        memory: "4 GiB"
        machine_type: "uefi"

        storage_devices:
          - name: "template-disk"
            type: "virtio_disk"
            source: "fedora-base"
            boot: 1
            capacity: "50 GB"

        network_devices:
          - name: "eth0"
            type: "virtio"

        tags:
          - "template"
          - "linux"
          - "fedora"

        state: "shutoff"  # Template state for cloning

Key Features¶

Template State: shutoff state makes it ready for cloning
UEFI Boot: Modern boot system for Linux
VirtIO Devices: High-performance storage and network
Fedora Base: Enterprise-ready Linux distribution
50GB Storage: Adequate space for OS and applications

Ubuntu Server¶

Production-ready Ubuntu server configuration with cloud-init.

Ubuntu Server Manifest¶

ubuntu-server.yaml

type: Application
version: "1.0.0"
metadata:
  name: "ubuntu-server"
  labels:
    - "os:ubuntu"
spec:
  assets:
    - name: "ubuntu-server"
      type: "virtual_disk"
      format: "raw"
      url: "https://cloud-images.ubuntu.com/releases/22.04/release/ubuntu-22.04-server-cloudimg-amd64.img"

  resources:
    - type: "virdomain"
      name: "ubuntu-server"
      spec:
        description: "Ubuntu 22.04 LTS server"
        cpu: 2
        memory: "4 GiB"
        machine_type: "uefi"

        storage_devices:
          - name: "root-disk"
            type: "virtio_disk"
            source: "ubuntu-server"
            boot: 1
            capacity: "40 GB"

        network_devices:
          - name: "eth0"
            type: "virtio"

        tags:
          - "ubuntu"
          - "server"
          - "production"

        state: "running"

        cloud_init_data:
          user_data: |
            #cloud-config
            package_update: true
            package_upgrade: true

            packages:
              - htop
              - curl
              - wget
              - git
              - unzip
              - software-properties-common
              - apt-transport-https
              - ca-certificates
              - gnupg
              - lsb-release

            # Create admin user
            users:
              - name: admin
                primary_group: admin
                shell: /bin/bash
                sudo: ALL=(ALL) NOPASSWD:ALL
                groups: sudo, adm
                lock_passwd: false
                ssh_authorized_keys:
                  - ssh-rsa AAAAB3NzaC1yc2E... # Add your SSH key

            # Basic security setup
            runcmd:
              - ufw --force enable
              - ufw default deny incoming
              - ufw default allow outgoing
              - ufw allow ssh
              - systemctl enable ssh
              - systemctl start ssh

          meta_data: |
            instance-id: ubuntu-server
            local-hostname: ubuntu-server

CentOS Stream¶

Enterprise Linux configuration with Red Hat ecosystem tools.

CentOS Stream Manifest (Note: QCOW2 support is coming in a later HyperCore release. For now, swap in an ISO or rw format centos image)¶

centos-stream.yaml

type: Application
version: "1.0.0"
metadata:
  name: "centos-stream"
  labels:
    - "os:centos"
    - "type:enterprise"
spec:
  assets:
    - name: "centos-stream"
      type: "virtual_disk"
      format: "qcow2"
      url: "https://cloud.centos.org/centos/9-stream/x86_64/images/CentOS-Stream-GenericCloud-9-latest.x86_64.qcow2"

  resources:
    - type: "virdomain"
      name: "centos-stream"
      spec:
        description: "CentOS Stream 9 enterprise server"
        cpu: 4
        memory: "8 GiB"
        machine_type: "uefi"

        storage_devices:
          - name: "root-disk"
            type: "virtio_disk"
            source: "centos-stream"
            boot: 1
            capacity: "80 GB"

        network_devices:
          - name: "eth0"
            type: "virtio"

        tags:
          - "centos"
          - "enterprise"
          - "rhel-ecosystem"

        state: "running"

        cloud_init_data:
          user_data: |
            #cloud-config
            package_update: true

            packages:
              - epel-release
              - htop
              - curl
              - wget
              - git
              - vim
              - bind-utils
              - net-tools
              - firewalld

            # Configure firewall
            runcmd:
              - systemctl enable firewalld
              - systemctl start firewalld
              - firewall-cmd --permanent --add-service=ssh
              - firewall-cmd --reload

              # SELinux configuration
              - setsebool -P httpd_can_network_connect on
              - semanage fcontext -a -t httpd_exec_t "/var/www/html(/.*)?"
              - restorecon -R /var/www/html

          meta_data: |
            instance-id: centos-stream
            local-hostname: centos-stream

Development Environment¶

Linux development environment with common tools and IDEs.

Development VM Manifest¶

dev-environment.yaml

type: Application
version: "1.0.0"
metadata:
  name: "dev-environment"
  labels:
    - "purpose:development"
    - "team:engineering"
spec:
  assets:
    - name: "ubuntu-dev"
      type: "virtual_disk"
      format: "raw"
      url: "https://your-dev-image-url.img"

  resources:
    - type: "virdomain"
      name: "dev-env"
      spec:
        description: "Linux development environment"
        cpu: 4
        memory: "8 GiB"
        machine_type: "uefi"

        storage_devices:
          - name: "system-disk"
            type: "virtio_disk"
            source: "ubuntu-dev"
            boot: 1
            capacity: "100 GB"
          - name: "projects-disk"
            type: "virtio_disk"
            capacity: "200 GB"

        network_devices:
          - name: "eth0"
            type: "virtio"

        tags:
          - "development"
          - "engineering"
          - "ide"

        state: "running"

        cloud_init_data:
          user_data: |
            #cloud-config
            package_update: true

            packages:
              # Development tools
              - build-essential
              - cmake
              - git
              - curl
              - wget
              - vim
              - nano
              - htop
              - tree
              - jq

              # Programming languages
              - python3
              - python3-pip
              - python3-venv
              - nodejs
              - npm
              - default-jdk

              # Container tools
              - docker.io
              - docker-compose

              # IDE and editors
              - code
              - vim
              - emacs

            # Create developer user
            users:
              - name: developer
                primary_group: developer
                shell: /bin/bash
                sudo: ALL=(ALL) NOPASSWD:ALL
                groups: sudo, docker, adm
                lock_passwd: false

            # Setup development directories
            runcmd:
              - mkdir -p /home/developer/projects
              - mkdir -p /home/developer/workspace
              - chown -R developer:developer /home/developer

              # Mount projects disk
              - mkfs.ext4 /dev/vdb
              - mount /dev/vdb /home/developer/projects
              - echo "/dev/vdb /home/developer/projects ext4 defaults 0 0" >> /etc/fstab

              # Docker setup
              - systemctl enable docker
              - systemctl start docker
              - usermod -aG docker developer

              # Install additional tools
              - snap install code --classic
              - snap install postman

          meta_data: |
            instance-id: dev-env
            local-hostname: dev-env

Common Linux Patterns¶

Package Management¶

# Ubuntu/Debian
packages:
  - apt-transport-https
  - software-properties-common
  - ca-certificates

# CentOS/RHEL
packages:
  - epel-release
  - yum-utils
  - device-mapper-persistent-data

User Management¶

users:
  - name: serviceuser
    system: true
    shell: /bin/false
    home: /var/lib/serviceuser
    create_home: true

  - name: developer
    groups: sudo, docker
    ssh_authorized_keys:
      - ssh-rsa AAAAB3NzaC1yc2E...

Service Configuration¶

runcmd:
  - systemctl enable myservice
  - systemctl start myservice
  - systemctl status myservice

  # Firewall rules
  - ufw allow 8080/tcp
  - firewall-cmd --permanent --add-port=8080/tcp

Storage Setup¶

# Format and mount additional storage
runcmd:
  - mkfs.ext4 /dev/vdb
  - mkdir -p /data
  - mount /dev/vdb /data
  - echo "/dev/vdb /data ext4 defaults 0 0" >> /etc/fstab

Best Practices¶

1. Template Management¶

Use shutoff state for template VMs
Set CPU to 0 prevents accidental bootup of templates
Minimize template size for faster cloning
Include essential packages only
Document template contents

2. Security Configuration¶

# Security hardening
runcmd:
  - ufw --force enable
  - fail2ban-server start
  - chmod 700 /home/user/.ssh
  - chmod 600 /home/user/.ssh/authorized_keys

3. Resource Optimization¶

# Appropriate sizing
cpu: 2              # For web servers
memory: "4294967296"  # 4GB for moderate workloads
capacity: 42949672960 # 40GB for OS + applications

4. Cloud-Init Best Practices¶

Test cloud-init configurations before deployment
Use package managers for software installation
Handle errors gracefully with proper scripting
Log activities for troubleshooting

Troubleshooting¶

Common Issues¶

Boot failures: Check UEFI vs BIOS settings
Package installation failures: Verify repository access
SSH access issues: Check firewall and SSH key configuration
Storage mounting failures: Validate disk device paths

Debug Commands¶

# Check cloud-init status
sudo cloud-init status

# View initialization logs
sudo cat /var/log/cloud-init-output.log

# Check system services
sudo systemctl status

Multi-VM Applications - Multiple Linux VMs
Kubernetes - Linux-based K8s clusters
Basic Examples - Fundamental configurations
GPU Applications - GPU-enabled Linux VMs

Next Steps¶

Customize templates for your specific needs
Add monitoring and logging configuration
Implement backup strategies
Scale to multi-VM deployments