Linode Image Builder

This project builds a bootable Ubuntu Server image from scratch using debootstrap, preconfigured for deployment on Linode as a custom image. It allows you to create a lightweight, reproducible, and portable system with preinstalled tools and custom files.

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💡 Purpose

This project was built to solve a real-world cost and upload limitation:

• Linode only allows custom images up to 6GB.
• Attempting to create an image from an existing VM (e.g. 20GB backups) fails.

We built this repo to:

• ✅ Reduce monthly VM costs by avoiding the snapshot/image storage model.
• ✅ Bypass Linode’s 6GB image size limit using a minimal debootstrap build.
• ✅ Include SSH access, preinstalled tools, user, and personal files inside the image.

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✅ Successful Boot on Linode Console

This image was tested successfully on a Linode VM using the LISH console:

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✅ Features

• Ubuntu 22.04 LTS (Jammy Jellyfish) base
• systemd and openssh-server pre-installed
• Netplan configured for DHCP (default interface: eth0)
• Root login via password enabled
• Optional non-root user with password
• Python 3, Git, Vim, Curl, Nano, Htop installed
• File injection into /root/ from the host system
• Gzipped image ready for Linode upload

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📦 Requirements

• Ubuntu or Debian host system
• Root access
• debootstrap, rsync, gzip, mount

Install dependencies (if missing):

sudo apt install debootstrap rsync gzip

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🛠️ Usage

1. Run the builder script

sudo ./build-image.sh

This script automates the creation of a bootable image. It:

• Creates a 6GB raw image file
• Mounts and bootstraps Ubuntu with debootstrap
• Installs system packages, configures hostname, fstab, netplan, and SSH
• Adds a non-root user and root password
• Injects files from your /root/ directory into the image
• Compresses the image to linode-fixed.img.gz

2. Upload to Linode

Go to the Linode Cloud Manager → Images and upload linode-fixed.img.gz.

3. Deploy VM using the custom image

• Create a new Linode
• Choose "Custom Image"
• Select linode-fixed.img.gz
• Deploy the instance

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📖 Included Files

build-image.sh

A complete bash script that builds and configures the bootable image automatically. You can run it directly or use it as a base for your own variations.

manual-steps.md

An alternative to the script above — a detailed step-by-step manual guide with command-by-command instructions. Ideal if you want to learn the process or debug.

post-boot-setup.md

A quick reference for what to do after booting your image on Linode, especially if:

• Networking is not working
• You get Permission denied with SSH

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🖥️ Post-boot setup (via LISH Console)

If networking doesn't come up:

ip a     # Identify interface (e.g. enp0s4)

cat <<EOF > /etc/netplan/01-netcfg.yaml
network:
  version: 2
  ethernets:
    enp0s4:
      dhcp4: true
EOF

netplan generate
netplan apply
ip link set enp0s4 up

If SSH login fails with “Permission denied”:

sed -i 's/#\?PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config
sed -i 's/#\?PasswordAuthentication.*/PasswordAuthentication yes/' /etc/ssh/sshd_config

# Add them manually if they don't exist
echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
echo "PasswordAuthentication yes" >> /etc/ssh/sshd_config

systemctl restart ssh

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📁 File structure

linode-image-builder/
├── build-image.sh       # Automated image creation script (raw image → debootstrap → compressed .gz)
├── manual-steps.md      # Manual step-by-step breakdown (every command in order, with comments)
├── post-boot.md         # What to do after you boot the image on Linode
├── images/              # Screenshots and documentation images
│   └── boot-success.png
├── LICENSE              # MIT License
├── README.md            # Project description, usage, and structure

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⚠️ Notes

• This image does not include a bootloader (GRUB). Linode uses its own kernel.
• Make sure your root password and SSH config allow login after boot.
• Test everything via LISH before relying on SSH access.

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🧑‍💻 Author

Made with ❤️ by Athanasios Sersemis MIT License