Prepare a SLES or openSUSE Leap virtual machine for Azure

บทความ
08/22/2024

Applies to: ✔️ Linux VMs ✔️ Flexible scale sets Applies to: ✔️ Uniform scale sets

In some cases, you might want to use customized SUSE Linux Enterprise Server (SLES) or openSUSE Leap Linux virtual machines (VMs) in your Azure environment and be able to build these types of VMs through automation. This article demonstrates how to create and upload a custom Azure virtual hard disk (VHD) that contains a SUSE Linux operating system.

Prerequisites

This article assumes that you already installed a SLES or openSUSE Leap Linux operating system on a virtual hard disk. Multiple tools exist to create .vhd files. For example, you can use a virtualization solution such as Hyper-V. For instructions, see Install Hyper-V and create a virtual machine.

SLES/openSUSE Leap installation notes

For more tips on preparing Linux images for Azure, see General Linux installation notes.
Azure doesn't support Windows Hard Disk Image (.vhdx) files. Only VHD (.vhd) files are supported outside virtual machines. You can convert the disk to VHD format by using Hyper-V Manager or the Convert-VHD cmdlet.
Azure supports Gen1 (BIOS boot) and Gen2 (UEFI boot) virtual machines.
The virtual file allocation table (VFAT) kernel module must be enabled in the kernel.
Don't configure a swap partition on the OS disk. You can configure the Linux agent to create a swap file on the temporary resource disk. Steps later in this article give more information about configuring swap space.
All VHDs on Azure must have a virtual size aligned to 1 MB. When you're converting from a raw disk to VHD, ensure that the raw disk size is a multiple of 1 MB before conversion. For more information, see General Linux installation notes.

Note

Cloud-init version 21.2 or later removes the user-defined function (UDF) requirement. But without the udf module enabled, the CD-ROM won't mount during provisioning, which prevents the custom data from being applied. A workaround is to apply user data. However, unlike custom data, user data isn't encrypted. For more information, see User data formats in the cloud-init documentation.

Use SUSE Studio

SUSE Studio can easily create and manage your SLES and openSUSE Leap images for Azure and Hyper-V. SUSE Studio is the recommended approach for customizing your own SLES and openSUSE Leap images.

As an alternative to building your own VHD, SUSE also publishes BYOS (bring your own subscription) images for SLES at VM Depot.

Prepare SLES for Azure

Configure the Azure and Hyper-V modules if required.

If your software hypervisor is not Hyper-V, other modules need to be added into the initial RAM disk (initramfs) to successfully boot in Azure.

Edit the /etc/dracut.conf file and add the following line to the file:
```
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
```
Run the dracut command to rebuild the initramfs file:
```
sudo dracut --verbose --force
```

Set up the serial console.

To successfully work with the serial console, you must set up several variables in the /etc/defaults/grub file and re-create GRUB on the server:

# Add console=ttyS0 and earlyprintk=ttS0 to the variable.
# Remove "splash=silent" and "quiet" options.
GRUB_CMDLINE_LINUX_DEFAULT="audit=1 no-scroll fbcon=scrollback:0 mitigations=auto security=apparmor crashkernel=228M,high crashkernel=72M,low console=ttyS0 earlyprintk=ttyS0"

# Add "console serial" to GRUB_TERMINAL.
GRUB_TERMINAL="console serial"

# Set the GRUB_SERIAL_COMMAND variable.

GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

/usr/sbin/grub2-mkconfig -o /boot/grub2/grub.cfg

Register your SUSE Linux Enterprise system to allow it to download updates and install packages.
Update the system with the latest patches:
```
sudo zypper update
```

Install the Azure Linux VM Agent (waagent) and cloud-init:

sudo SUSEConnect -p sle-module-public-cloud/15.2/x86_64  (SLES 15 SP2)
sudo zypper refresh
sudo zypper install python-azure-agent
sudo zypper install cloud-init

Enable waagent and cloud-init to start on boot:

sudo systemctl enable  waagent
sudo systemctl enable cloud-init-local.service
sudo systemctl enable cloud-init.service
sudo systemctl enable cloud-config.service
sudo systemctl enable cloud-final.service
sudo systemctl daemon-reload
sudo cloud-init clean

Update the cloud-init configuration:

cat <<EOF | sudo tee /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg
datasource_list: [ Azure ]
datasource:
    Azure:
        apply_network_config: False

EOF

sudo cat <<EOF | sudo tee  /etc/cloud/cloud.cfg.d/05_logging.cfg
# This tells cloud-init to redirect its stdout and stderr to
# 'tee -a /var/log/cloud-init-output.log' so the user can see output
# there without needing to look on the console.
output: {all: '| tee -a /var/log/cloud-init-output.log'}
EOF

# Make sure mounts and disk_setup are in the init stage:
echo "Adding mounts and disk_setup to init stage"
sudo sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
sudo sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
sudo sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
sudo sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg

If you want to mount, format, and create a swap partition, one option is to pass in a cloud-init configuration every time you create a VM.

Another option is to use a cloud-init directive in the image to configure swap space every time the VM is created:

cat  <<EOF | sudo tee -a /etc/systemd/system.conf
'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"'
EOF

cat <<EOF | sudo tee /etc/cloud/cloud.cfg.d/00-azure-swap.cfg
#cloud-config
# Generated by Azure cloud image build
disk_setup:
  ephemeral0:
    table_type: mbr
    layout: [66, [33, 82]]
    overwrite: True
fs_setup:
  - device: ephemeral0.1
    filesystem: ext4
  - device: ephemeral0.2
    filesystem: swap
mounts:
  - ["ephemeral0.1", "/mnt"]
  - ["ephemeral0.2", "none", "swap", "sw,nofail,x-systemd.requires=cloud-init.service,x-systemd.device-timeout=2", "0", "0"]
EOF

Previously, the Azure Linux Agent was used to automatically configure swap space by using the local resource disk that's attached to the virtual machine after the virtual machine is provisioned on Azure. Because cloud-init now handles this step, you must not use the Azure Linux Agent to format the resource disk or create the swap file. Use these commands to modify /etc/waagent.conf appropriately:
```
sudo sed -i 's/Provisioning.UseCloudInit=n/Provisioning.UseCloudInit=auto/g' /etc/waagent.conf
sudo sed -i 's/Provisioning.Enabled=y/Provisioning.Enabled=n/g' /etc/waagent.conf
sudo sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
sudo sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf
```
Note

If you're using a cloud-init version earlier than 21.2, make sure the udf module is enabled. Removing or disabling it will cause a provisioning or boot failure. Cloud-init version 21.2 or later removes the UDF requirement.
Ensure that the /etc/fstab file references the disk by using its UUID (by-uuid).
Remove udev rules and network adapter configuration files to avoid generating static rules for the Ethernet interfaces. These rules can cause problems when you're cloning a virtual machine in Microsoft Azure or Hyper-V.
```
sudo rm -f /etc/udev/rules.d/70-persistent-net.rules
sudo rm -f /etc/udev/rules.d/85-persistent-net-cloud-init.rules
sudo rm -f /etc/sysconfig/network/ifcfg-eth*
```
We recommend that you edit the /etc/sysconfig/network/dhcp file and change the DHCLIENT_SET_HOSTNAME parameter to the following:
```
DHCLIENT_SET_HOSTNAME="no"
```

In the /etc/sudoers file, comment out or remove the following lines if they exist:

Defaults targetpw   # Ask for the password of the target user i.e. root
ALL    ALL=(ALL) ALL   # WARNING! Only use this setting together with 'Defaults targetpw'!

Ensure that the Secure Shell (SSH) server is installed and configured to start at boot time:
```
sudo systemctl enable sshd
```
Clean the cloud-init stage:
```
sudo cloud-init clean --seed --logs
```
Run the following commands to deprovision the virtual machine and prepare it for provisioning on Azure.

If you're migrating a specific virtual machine and don't want to create a generalized image, skip the deprovisioning step.
```
sudo rm -f /var/log/waagent.log
sudo waagent -force -deprovision+user
sudo export HISTSIZE=0
sudo rm -f ~/.bash_history
```

Prepare openSUSE 15.4+

On the center pane of Hyper-V Manager, select the virtual machine.
Select Connect to open the window for the virtual machine.

In a terminal, run the command zypper lr. If this command returns output similar to the following example, the repositories are configured as expected and no adjustments are necessary. (Version numbers might vary.)

#	Alias	Name	Enabled	GPG Check	Refresh
1	Cloud:Tools_15.4	Cloud:Tools->	Yes	(r ) Yes	Yes
2	openSUSE_stable_OSS	openSUSE_st->	Yes	(r ) Yes	Yes
3	openSUSE_stable_Updates	openSUSE_st->	Yes	(r ) Yes	Yes

If the the message "No repositories defined" appears from the zypper lr the repositories must be added manually.

Below are examples of commands for adding these repositories (versions and links may vary):

sudo zypper ar -f https://download.opensuse.org/update/openSUSE-stable openSUSE_stable_Updates
sudo zypper ar -f https://download.opensuse.org/repositories/Cloud:/Tools/15.4 Cloud:Tools_15.4
sudo zypper ar -f https://download.opensuse.org/distribution/openSUSE-stable/repo/oss openSUSE_stable_OSS

You can then verify that the repositories have been added by running the command zypper lr again. If one of the relevant update repositories isn't enabled, enable it by using the following command:

sudo zypper mr -e [NUMBER OF REPOSITORY]

Update the kernel to the latest available version:
```
sudo zypper up kernel-default
```
Or update the operating system with all the latest patches:
```
sudo zypper update
```
Install the Azure Linux Agent:
```
sudo zypper install WALinuxAgent
```
Modify the kernel boot line in your GRUB configuration to include other kernel parameters for Azure. To do this, open /boot/grub/menu.lst in a text editor and ensure that the default kernel includes the following parameters:
```
console=ttyS0 earlyprintk=ttyS0
```
This option ensures that all console messages are sent to the first serial port, which can assist Azure support with debugging issues. In addition, remove the following parameters from the kernel boot line if they exist:
```
 libata.atapi_enabled=0 reserve=0x1f0,0x8
```
We recommend that you edit the /etc/sysconfig/network/dhcp file and change the DHCLIENT_SET_HOSTNAME parameter to the following setting:
```
 DHCLIENT_SET_HOSTNAME="no"
```

In the /etc/sudoers file, comment out or remove the following lines if they exist. This is an important step.

Defaults targetpw   # ask for the password of the target user i.e. root
ALL    ALL=(ALL) ALL   # WARNING! Only use this together with 'Defaults targetpw'!

Ensure that the SSH server is installed and configured to start at boot time.
Don't create swap space on the OS disk.

The Azure Linux Agent can automatically configure swap space by using the local resource disk that's attached to the VM after provisioning on Azure. The local resource disk is a temporary disk and will be emptied when the VM is deprovisioned.

After you install the Azure Linux Agent, modify the parameters in /etc/waagent.conf as follows:
```
ResourceDisk.Format=n
ResourceDisk.Filesystem=ext4
ResourceDisk.MountPoint=/mnt/resource
ResourceDisk.EnableSwap=n
ResourceDisk.SwapSizeMB=2048    ## NOTE: set the size to whatever you need it to be.
```
Ensure that the Azure Linux Agent runs at startup:
```
sudo systemctl enable waagent.service
```

Run the following commands to deprovision the virtual machine and prepare it for provisioning on Azure.

If you're migrating a specific virtual machine and don't want to create a generalized image, skip the deprovisioning step.

sudo rm -f ~/.bash_history # Remove current user history
sudo rm -rf /var/lib/waagent/
sudo rm -f /var/log/waagent.log
sudo waagent -force -deprovision+user
sudo rm -f ~/.bash_history # Remove root user history
sudo export HISTSIZE=0

Select Action > Shut Down in Hyper-V Manager.

Next steps

You're now ready to use your SUSE Linux VHD to create new virtual machines in Azure. If this is the first time that you're uploading the .vhd file to Azure, see Create a Linux VM from a custom disk.

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