Preparing your disk image

You can use your own file with a Linux-based VM disk image. Once your image is prepared, upload it to Compute Cloud.

If you made software that might be helpful to other others, offer it on Yandex Cloud Marketplace.

Configure the OS to meet the requirementsConfigure the OS to meet the requirements

Boot disk images must meet the following requirements:

• The virtio-net, virtio-blk, and virtio-pci drivers are installed. If you are going to attach file storages to your VM, you also need to install the virtiofs driver. For more information, refer to this guide.
• The ttyS0 terminal (COM1 port) is set up as a serial console. For more information, refer to this guide.
• The network interface runs correctly when starting a VM and obtains the IP address via DHCP.
• The cloud-init package is installed and configured to work with our metadata service. To install the package for CentOS, run the sudo yum install cloud-init command. To install it for Debian or Ubuntu, run sudo apt update && sudo apt install -y cloud-init.
• If you created an image based on an Amazon Machine Image (AMI), verification of the cloud platform where the VM instance is run is disabled in the cloud-init settings. For more information, refer to this guide.
• In the system firewall settings, the minimum required set of ports for running your applications and a port for SSH access (by default, 22 TCP) are open.
• The SSH server starts automatically at VM startup.
• Services running your application are resistant to VM reboots.
• The boot disk uses MBR partitioning.
• The disk is mounted by its UUID rather than by name.
• The file system is not encrypted.

Install the virtio driversInstall the virtio drivers

To successfully upload your image, make sure to install the virtio-blk, virtio-net, and virtio-pci drivers. To use Compute Cloud file storage, install virtiofs drivers.

Most modern distributions contain the virtio drivers by default. They can be compiled as separate .ko files or be part of the kernel itself.

Follow the guide below to check if the drivers are installed; if they are not, add them.

1. Find out whether the drivers are included in the kernel configuration:

   How do I find out?

   Run this command:

   grep -E -i "VIRTIO_(BLK|NET|PCI|FS)" /boot/config-$(uname -r)
   

   If no lines starting with CONFIG_VIRTIO_BLK=, CONFIG_VIRTIO_NET=, CONFIG_VIRTIO_PCI=, and CONFIG_VIRTIO_FS= are displayed, you should recompile the Linux kernel with the virtio drivers. Otherwise, proceed to the next steps.

2. If the CONFIG_VIRTIO_BLK=y, CONFIG_VIRTIO_NET=y, CONFIG_VIRTIO_PCI=y, and CONFIG_VIRTIO_FS=y lines are returned in step 1, check whether the drivers are included in the kernel:

   How to check if drivers are included in a kernel

   Run this command:

   grep -E "virtio(_blk|_net|_pci|fs)" /lib/modules/"$(uname -r)"/modules.builtin
   

   • If the lines with the virtio_net.ko, virtio_blk.ko, virtio_pci.ko, and virtiofs.ko filenames are returned, the drivers are part of the kernel and you do not need to install them.
   • If not, recompile the Linux kernel with the virtio drivers.

3. If the CONFIG_VIRTIO_BLK=m, CONFIG_VIRTIO_NET=m, CONFIG_VIRTIO_PCI=m, and CONFIG_VIRTIO_FS=m lines are returned in step 1, check whether the drivers are installed as kernel modules:

   How to check if drivers belong to a module

   CentOS/Fedora

   Debian/Ubuntu

   Run the following command:

   sudo lsinitrd /boot/initramfs-$(uname -r).img | grep -E "virtio(_blk|_net|_pci|fs)"
   

   • If the lines with the virtio_net.ko.xz, virtio_blk.ko.xz, virtio_pci.ko.xz, and virtiofs.ko.xz filenames are returned, the drivers are installed as kernel modules.

   • If not, create a backup of the initramfs file and install the drivers:

     sudo cp /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r).img.bak
     sudo mkinitrd -f --with=virtio_blk --with=virtio_net --with=virtio_pci --with=virtiofs /boot/initramfs-$(uname -r).img $(uname -r)
     

     If you receive an error saying Command 'mkinitrd' not found, use dracut to install the drivers:

     sudo dracut -f --add-drivers "virtio_blk virtio_net virtio_pci virtiofs" /boot/initramfs-$(uname -r).img $(uname -r)
     

     Then restart the OS and check that the drivers appear in the initramfs file and are loaded:

     sudo lsinitrd /boot/initramfs-$(uname -r).img | grep -E "virtio(_blk|_net|_pci|fs)"
     find /lib/modules/"$(uname -r)"/ -name "virtio*" | grep -E "(blk|net|pci|fs)"
     

     After running each of the commands, the lines with the virtio_net.ko.xz, virtio_blk.ko.xz, virtio_pci.ko.xz, and virtiofs.ko.xz filenames should be returned.

   Run the following command:

   lsinitramfs /boot/initrd.img-$(uname -r) | grep -E "virtio(_blk|_net|_pci|fs)"
   

   • If the lines with the virtio_net.ko, virtio_blk.ko, virtio_pci.ko, and virtiofs.ko filenames are returned, the drivers are installed as kernel modules.

   • If not, install the drivers:

     echo -e "virtio_blk\nvirtio_net\nvirtio_pci\nvirtiofs" | sudo tee -a /etc/initramfs-tools/modules
     sudo update-initramfs -u
     

     Then restart the OS and check that the drivers appear in the initrd file and are loaded:

     lsinitramfs /boot/initrd.img-$(uname -r) | grep -E "virtio(_blk|_net|_pci|fs)"
     find /lib/modules/"$(uname -r)"/ -name "virtio*" | grep -E "(blk|net|pci|fs)"
     

     After running each of the commands, the lines with the virtio_net.ko, virtio_blk.ko, virtio_pci.ko, and virtiofs.ko filenames should be returned.

Configure the serial consoleConfigure the serial console

The serial console allows you to access your VM regardless of the network or OS status. Use the serial console to troubleshoot your VM or when you have issues with SSH access. For more information, see Getting started with the serial console.

To connect to your VM using the serial console, set up the ttyS0 terminal (COM1 port) as a system console for your image:

1. In the /etc/default/grub file with GRUB settings, add console=ttyS0 to the GRUB_CMDLINE_LINUX parameter value. The line with this parameter should look like this:

   GRUB_CMDLINE_LINUX="foo=bar baz console=ttyS0"
   

2. Check that the /etc/securetty file with a list of terminals, through which the root user can log in to the OS, contains the ttyS0 line. If there is no such file, create one.

   Note

   In some operating systems, the /etc/securetty file is disabled and the root user is allowed to access all terminals by default. To configure access using this file, add to the /etc/pam.d/login file a pointer to the pam_securetty.so module. For more information, see man pam_securetty and man pam.d.

3. Run the following commands:

   CentOS/Fedora

   Debian/Ubuntu

   sudo stty -F /dev/ttyS0 9600 # Sets the recommended baud rate for the ttyS0 terminal at 9600.
   sudo grub2-mkconfig -o /boot/grub2/grub.cfg # Generates a configuration file for GRUB.
   sudo systemctl start getty@ttyS0 # Starts getty on the ttyS0 terminal.
   sudo systemctl enable getty@ttyS0 # Specifies that getty should be run every time the OS is started.
   

   sudo stty -F /dev/ttyS0 9600 # Sets the recommended baud rate for the ttyS0 terminal at 9600.
   sudo update-grub # Generates a configuration file for GRUB.
   sudo systemctl start getty@ttyS0 # Starts getty on the ttyS0 terminal.
   sudo systemctl enable getty@ttyS0 # Specifies that getty should be run every time the OS is started.
   

4. Restart the OS.

After creating a VM from your image, you should additionally configure it to work with the serial console.

Disable verification of the cloud platform when creating an image in Amazon EC2Disable verification of the cloud platform when creating an image in Amazon EC2

If you are creating an image in Amazon EC2 based on an Amazon Machine Image, cloud-init checks that the VM can be run in Amazon EC2. VMs in Yandex Compute Cloud will fail the check and may run incorrectly.

To avoid this, disable metadata verification on your VMs. To do this, in the /etc/cloud/cloud.cfg.d directory, create a configuration file, e.g., 99-ec2-datasource.cfg, and add the following code to it:

#cloud-config
datasource:
  Ec2:
    strict_id: false

Install drivers to enable compatibility with GPUsInstall drivers to enable compatibility with GPUs

If working with a VM requires a GPU, install NVIDIA drivers while preparing the image.

Create an image fileCreate an image file

The supported formats include Qcow2, VMDK, RAW, and VHD.

We recommend that you use Qcow2 format with an optimized cluster size for faster import. To convert your image from other formats, use the qemu-img utility:

qemu-img convert -p -O qcow2 -o cluster_size=2M <your_image_file_name> <new_image_file_name>