Add basic custom ubuntu image guide

2025-02-21 01:41:12 -08:00 · 2025-02-21 01:41:12 -08:00 · 18b84313d4
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+# Creating a Custom Ubuntu Server Installation Image
+
+This guide walks through the process of creating a customized Ubuntu Server installation image with automated setup.
+
+## Prerequisites
+
+Install the required tools:
+
+```bash
+sudo apt install xorriso
+```
+
+## Step 1: Extract the Original ISO Contents
+
+```bash
+# Create working directory
+mkdir -p ubuntu-custom/{extract,iso}
+
+# Enter the working directory
+cd ubuntu-custom
+
+# Download the iso file if we don't have it already
+test -e ubuntu-24.04.2-live-server-amd64.iso || curl -O https://releases.ubuntu.com/24.04.2/ubuntu-24.04.2-live-server-amd64.iso
+
+# Mount the original ISO
+sudo mount -o loop ubuntu-24.04.2-live-server-amd64.iso iso
+
+# Copy all contents
+rsync -av iso/ extract/
+
+# Unmount when done
+sudo umount iso/
+```
+
+## Step 2: Create Autoinstall Configuration
+
+```bash
+# Create directory for autoinstall files
+chmod u+w extract/casper/
+mkdir -p extract/casper/autoinstall/
+
+# Create user-data file with your configuration
+cat > extract/casper/autoinstall/user-data << 'EOF'
+#cloud-config
+autoinstall:
+  version: 1
+  locale: en_US
+  keyboard:
+    layout: us
+  storage:
+    layout:
+      name: direct
+  identity:
+    hostname: myserver
+    username: user
+    # Generate with: mkpasswd --method=SHA-512
+    password: $6$rounds=4096$....
+  ssh:
+    install-server: yes
+    authorized-keys:
+      - ssh-rsa AAAAB3N....
+  packages:
+    - openssh-server
+    - fail2ban
+    - ufw
+  user-data:
+    disable_root: true
+  late-commands:
+    - echo 'user ALL=(ALL) NOPASSWD:ALL' > /target/etc/sudoers.d/user
+    - curtin in-target -- ufw allow OpenSSH
+    - curtin in-target -- ufw --force enable
+EOF
+
+# Create empty meta-data file (required)
+touch extract/casper/autoinstall/meta-data
+```
+
+## Step 3: Modify Boot Configuration
+
+Edit the GRUB configuration to enable autoinstall:
+
+```bash
+# Backup original config
+chmod u+w extract/boot/grub/
+cp extract/boot/grub/grub.cfg extract/boot/grub/grub.cfg.backup
+
+# Edit the grub.cfg file
+nano extract/boot/grub/grub.cfg
+```
+
+Replace or modify the first menuentry to:
+
+```
+menuentry "Automated Ubuntu Server Install" {
+    set gfxpayload=keep
+    linux /casper/vmlinuz autoinstall ds=nocloud\;s=/cdrom/casper/autoinstall/ quiet ---
+    initrd /casper/initrd
+}
+```
+
+## Step 4: Create the Custom ISO
+
+```bash
+xorriso -as mkisofs -r \
+  -V "Ubuntu Custom" \
+  -o custom-ubuntu.iso \
+  -J -joliet-long \
+  -b boot/grub/i386-pc/eltorito.img \
+  -no-emul-boot -boot-load-size 4 -boot-info-table \
+  -eltorito-alt-boot -e EFI/boot/bootx64.efi \
+  -no-emul-boot \
+  extract/
+```
+
+## Step 5: Test the ISO
+
+Test the ISO using a virtual machine:
+
+```bash
+# With QEMU
+qemu-img create -f qcow2 test-disk.qcow2 20G
+qemu-system-x86_64 -cdrom custom-ubuntu.iso \
+  -drive file=test-disk.qcow2,format=qcow2,if=virtio \
+  -m 2048
+```
+
+## Additional Customization Options
+
+You can expand the `user-data` file to include:
+
+1. Additional packages
+2. Custom scripts to run during installation
+3. Network configuration
+4. More complex storage layouts with custom partitioning
+5. Time zone and locale settings
+
+## Troubleshooting
+
+If the installer doesn't automate:
+- Check that the paths in the kernel parameters match where you placed the autoinstall files
+- Verify the syntax of your user-data file
+- Ensure both user-data and meta-data files exist