Prepare a Red Hat-based virtual machine for Azure

Article
03/20/2023
32 minutes to read

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

In this article, you'll learn how to prepare a Red Hat Enterprise Linux (RHEL) virtual machine for use in Azure. The versions of RHEL that are covered in this article are 6.7+ and 7.1+. The hypervisors for preparation that are covered in this article are Hyper-V, kernel-based virtual machine (KVM), and VMware. For more information about eligibility requirements for participating in Red Hat's Cloud Access program, see Red Hat's Cloud Access website and Running RHEL on Azure. For ways to automate building RHEL images, see Azure Image Builder.

Note

Be aware of versions that are End Of Life (EOL) and no longer supported by Redhat. Uploaded image that are, at or beyond EOL will be supported on a reasonable business effort basis. Link to Redhat's Product Lifecycle

Hyper-V Manager

This section shows you how to prepare a RHEL 6, RHEL 7, or RHEL 8 virtual machine using Hyper-V Manager.

Prerequisites

This section assumes that you've already obtained an ISO file from the Red Hat website and installed the RHEL image to a virtual hard disk (VHD). For more details about how to use Hyper-V Manager to install an operating system image, see Install the Hyper-V Role and Configure a Virtual Machine.

RHEL installation notes

Azure doesn't support the VHDX format. Azure supports only fixed VHD. You can use Hyper-V Manager to convert the disk to VHD format, or you can use the convert-vhd cmdlet. If you use VirtualBox, select Fixed size as opposed to the default dynamically allocated option when you create the disk.
Azure supports Gen1 (BIOS boot) & Gen2 (UEFI boot) Virtual machines.
The maximum size that's allowed for the VHD is 1,023 GB.
The vfat kernel module must be enabled in the kernel.
Logical Volume Manager (LVM) is supported and may be used on the OS disk or data disks in Azure virtual machines. However, in general its recommended to use standard partitions on the OS disk rather than LVM. This practice will avoid LVM name conflicts with cloned virtual machines, particularly if you ever need to attach an operating system disk to another identical virtual machine for troubleshooting. See also LVM and RAID documentation.
Kernel support for mounting Universal Disk Format (UDF) file systems is required. At first boot on Azure, the UDF-formatted media that is attached to the guest passes the provisioning configuration to the Linux virtual machine. The Azure Linux Agent must be able to mount the UDF file system to read its configuration and provision the virtual machine, without this, provisioning will fail!
Don't configure a swap partition on the operating system disk. More information about this can be found in the following steps.
All VHDs on Azure must have a virtual size aligned to 1MB. When converting from a raw disk to VHD you must ensure that the raw disk size is a multiple of 1MB before conversion. More details can be found in the steps below. See also Linux Installation Notes for more information.

Note

(Cloud-init >= 21.2 removes the udf requirement.) however without the udf module enabled the cdrom will not mount during provisioning preventing custom data from being applied. A workaround for this would be to apply custom data using user data however, unlike custom data user data is not encrypted. https://cloudinit.readthedocs.io/en/latest/topics/format.html

RHEL 6 using Hyper-V Manager

In Hyper-V Manager, select the virtual machine.
Click Connect to open a console window for the virtual machine.
In RHEL 6, NetworkManager can interfere with the Azure Linux agent. Uninstall this package by running the following command:
```
# sudo rpm -e --nodeps NetworkManager
```
Create or edit the /etc/sysconfig/network file, and add the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```
Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:
```
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
```
Move (or remove) the udev rules to avoid generating static rules for the Ethernet interface. These rules cause problems when you clone a virtual machine in Microsoft Azure or Hyper-V:
```
# sudo ln -s /dev/null /etc/udev/rules.d/75-persistent-net-generator.rules

# sudo rm -f /etc/udev/rules.d/70-persistent-net.rules
```
Ensure that the network service will start at boot time by running the following command:
```
# sudo chkconfig network on
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# sudo subscription-manager register --auto-attach --username=XXX --password=XXX
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-6-server-extras-rpms
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this modification, open /boot/grub/menu.lst in a text editor, and ensure that the default kernel includes the following parameters:
```
console=ttyS0 earlyprintk=ttyS0 
```
This will also ensure that all console messages are sent to the first serial port, which can assist Azure support with debugging issues.

In addition, we recommended that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more. This configuration might be problematic on smaller virtual machine sizes.
Ensure that the secure shell (SSH) server is installed and configured to start at boot time, which is usually the default. Modify /etc/ssh/sshd_config to include the following line:
```
ClientAliveInterval 180
```
Install the Azure Linux Agent by running the following command:
```
# sudo yum install WALinuxAgent

# sudo chkconfig waagent on
```
Installing the WALinuxAgent package removes the NetworkManager and NetworkManager-gnome packages if they weren't already removed in step 3.
Don't create swap space on the operating system disk.

The Azure Linux Agent can automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. Note that the local resource disk is a temporary disk and that it might be emptied if the virtual machine is deprovisioned. After you install the Azure Linux Agent in the previous step, modify the following parameters in /etc/waagent.conf appropriately:
```
ResourceDisk.Format=y
ResourceDisk.Filesystem=ext4
ResourceDisk.MountPoint=/mnt/resource
ResourceDisk.EnableSwap=y
ResourceDisk.SwapSizeMB=2048    ## NOTE: set this to whatever you need it to be.
```
Unregister the subscription (if necessary) by running the following command:
```
# sudo subscription-manager unregister
```

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

# Note: if you're migrating a specific virtual machine and don't wish to create a generalized image,
# skip the deprovision step
# sudo waagent -force -deprovision

# export HISTSIZE=0

# logout

Click Action > Shut Down in Hyper-V Manager. Your Linux VHD is now ready to be uploaded to Azure.

RHEL 7 using Hyper-V Manager

In Hyper-V Manager, select the virtual machine.
Click Connect to open a console window for the virtual machine.
Create or edit the /etc/sysconfig/network file, and add the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```

Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
PERSISTENT_DHCLIENT=yes
NM_CONTROLLED=yes

Ensure that the network service will start at boot time by running the following command:
```
# sudo systemctl enable network
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# sudo subscription-manager register --auto-attach --username=XXX --password=XXX
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this modification, open /etc/default/grub in a text editor, and edit the GRUB_CMDLINE_LINUX parameter. For example:
```
GRUB_CMDLINE_LINUX="console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 earlyprintk=ttyS0 net.ifnames=0"
GRUB_TERMINAL_OUTPUT="serial console"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
```
This will also ensure that all console messages are sent to the first serial port and enable interaction with the serial console, which can assist Azure support with debugging issues. This configuration also turns off the new RHEL 7 naming conventions for NICs.
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
After you're done editing /etc/default/grub, run the following command to rebuild the grub configuration:
```
# sudo grub2-mkconfig -o /boot/grub2/grub.cfg
```
Note

If uploading an UEFI enabled VM, the command to update grub is grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg.
Ensure that the SSH server is installed and configured to start at boot time, which is usually the default. Modify /etc/ssh/sshd_config to include the following line:
```
ClientAliveInterval 180
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-7-server-extras-rpms
```

Install the Azure Linux Agent, cloud-init and other necessary utilities by running the following command:

# sudo yum install -y WALinuxAgent cloud-init cloud-utils-growpart gdisk hyperv-daemons

# sudo systemctl enable waagent.service
# sudo systemctl enable cloud-init.service

Configure cloud-init to handle the provisioning:

Configure waagent for cloud-init:

sed -i 's/Provisioning.Agent=auto/Provisioning.Agent=auto/g' /etc/waagent.conf
sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf

Note

If you are migrating a specific virtual machine and don't wish to create a generalized image, set Provisioning.Agent=disabled on the /etc/waagent.conf config.

Configure mounts:

echo "Adding mounts and disk_setup to init stage"
sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg

Configure Azure datasource:

echo "Allow only Azure datasource, disable fetching network setting via IMDS"
cat > /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg <<EOF
datasource_list: [ Azure ]
datasource:
    Azure:
        apply_network_config: False
EOF

If configured, remove existing swapfile:

if [[ -f /mnt/resource/swapfile ]]; then
echo "Removing swapfile" #RHEL uses a swapfile by defaul
swapoff /mnt/resource/swapfile
rm /mnt/resource/swapfile -f
fi

Configure cloud-init logging:

echo "Add console log file"
cat >> /etc/cloud/cloud.cfg.d/05_logging.cfg <<EOF

# 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

Swap configuration Don't create swap space on the operating system disk.

Previously, the Azure Linux Agent was used automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. However this is now handled by cloud-init, you must not use the Linux Agent to format the resource disk create the swap file, modify the following parameters in /etc/waagent.conf appropriately:
```
ResourceDisk.Format=n
ResourceDisk.EnableSwap=n
```
If you want mount, format and create swap you can either:
- Pass this in as a cloud-init config every time you create a VM through customdata. This is the recommended method.
- Use a cloud-init directive baked into the image that will do this every time the VM is created.
```
echo 'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"' >> /etc/systemd/system.conf
cat > /etc/cloud/cloud.cfg.d/00-azure-swap.cfg << EOF
#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
```
If you want to unregister the subscription, run the following command:
```
# sudo subscription-manager unregister
```
Deprovision

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

Caution

If you are migrating a specific virtual machine and don't wish to create a generalized image, skip the deprovision step. Running the command waagent -force -deprovision+user will render the source machine unusable, this step is intended only to create a generalized image.
```
 # sudo rm -f /var/log/waagent.log
 # sudo cloud-init clean
 # waagent -force -deprovision+user
 # rm -f ~/.bash_history
 # export HISTSIZE=0
 # logout
```
Click Action > Shut Down in Hyper-V Manager. Your Linux VHD is now ready to be uploaded to Azure.

RHEL 8 using Hyper-V Manager

In Hyper-V Manager, select the virtual machine.
Click Connect to open a console window for the virtual machine.
Ensure that the Network Manager service will start at boot time by running the following command:
```
# sudo systemctl enable NetworkManager.service
```
Configure the network interface to automatically start at boot and use DHCP:
```
# nmcli con mod eth0 connection.autoconnect yes ipv4.method auto
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# sudo subscription-manager register --auto-attach --username=XXX --password=XXX
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure and enable the serial console.
1. Remove current GRUB parameters:
```
# grub2-editenv - unset kernelopts
```
1. Edit /etc/default/grub in a text editor, and add the following parameters:
```
GRUB_CMDLINE_LINUX="console=tty1 console=ttyS0,115200n8 earlyprintk=ttyS0,115200 earlyprintk=ttyS0 net.ifnames=0"
GRUB_TERMINAL_OUTPUT="serial console"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
```
This will also ensure that all console messages are sent to the first serial port and enable interaction with the serial console, which can assist Azure support with debugging issues. This configuration also turns off the new naming conventions for NICs.
1. Additionally, we recommend that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
After you are done editing /etc/default/grub, run the following command to rebuild the grub configuration:
```
# sudo grub2-mkconfig -o /boot/grub2/grub.cfg
```
And for an UEFI enabled VM, run the following command:
```
# sudo grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
```
Ensure that the SSH server is installed and configured to start at boot time, which is usually the default. Modify /etc/ssh/sshd_config to include the following line:
```
ClientAliveInterval 180
```

Install the Azure Linux Agent, cloud-init and other necessary utilities by running the following command:

# sudo yum install -y WALinuxAgent cloud-init cloud-utils-growpart gdisk hyperv-daemons

# sudo systemctl enable waagent.service
# sudo systemctl enable cloud-init.service

Configure cloud-init to handle the provisioning:

Configure waagent for cloud-init:

sed -i 's/Provisioning.Agent=auto/Provisioning.Agent=cloud-init/g' /etc/waagent.conf
sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf

Note

If you are migrating a specific virtual machine and don't wish to create a generalized image, set Provisioning.Agent=disabled on the /etc/waagent.conf config.

Configure mounts:

echo "Adding mounts and disk_setup to init stage"
sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg

Configure Azure datasource:

echo "Allow only Azure datasource, disable fetching network setting via IMDS"
cat > /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg <<EOF
datasource_list: [ Azure ]
datasource:
    Azure:
        apply_network_config: False
EOF

If configured, remove existing swapfile:

if [[ -f /mnt/resource/swapfile ]]; then
echo "Removing swapfile" #RHEL uses a swapfile by defaul
swapoff /mnt/resource/swapfile
rm /mnt/resource/swapfile -f
fi

Configure cloud-init logging:

echo "Add console log file"
cat >> /etc/cloud/cloud.cfg.d/05_logging.cfg <<EOF

# 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

Swap configuration Don't create swap space on the operating system disk.

Previously, the Azure Linux Agent was used automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. However this is now handled by cloud-init, you must not use the Linux Agent to format the resource disk create the swap file, modify the following parameters in /etc/waagent.conf appropriately:
```
ResourceDisk.Format=n
ResourceDisk.EnableSwap=n
```
- Pass this in as a cloud-init config every time you create a VM through customdata. This is the recommended method.
- Use a cloud-init directive baked into the image that will do this every time the VM is created.
```
echo 'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"' >> /etc/systemd/system.conf
cat > /etc/cloud/cloud.cfg.d/00-azure-swap.cfg << EOF
#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.device-timeout=2,x-systemd.requires=cloud-init.service", "0", "0"]
EOF
```
If you want to unregister the subscription, run the following command:
```
# sudo subscription-manager unregister
```
Deprovision

Run the following commands to deprovision the virtual machine and prepare it for provisioning on Azure:
```
 # sudo cloud-init clean
 # waagent -force -deprovision+user
 # rm -f ~/.bash_history
 # sudo rm -f /var/log/waagent.log
 # export HISTSIZE=0
 # logout
```
Caution

If you are migrating a specific virtual machine and don't wish to create a generalized image, skip the deprovision step. Running the command waagent -force -deprovision+user will render the source machine unusable, this step is intended only to create a generalized image.
Click Action > Shut Down in Hyper-V Manager. Your Linux VHD is now ready to be uploaded to Azure.

KVM

This section shows you how to use KVM to prepare a RHEL 6 or RHEL 7 distro to upload to Azure.

RHEL 6 using KVM

Download the KVM image of RHEL 6 from the Red Hat website.
Set a root password.

Generate an encrypted password, and copy the output of the command:
```
# openssl passwd -1 changeme
```
Set a root password with guestfish:
```
# guestfish --rw -a <image-name>
> <fs> run
> <fs> list-filesystems
> <fs> mount /dev/sda1 /
> <fs> vi /etc/shadow
> <fs> exit
```
Change the second field of the root user from "!!" to the encrypted password.
Create a virtual machine in KVM from the qcow2 image. Set the disk type to qcow2, and set the virtual network interface device model to virtio. Then, start the virtual machine, and sign in as root.
Create or edit the /etc/sysconfig/network file, and add the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```
Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:
```
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
```
Move (or remove) the udev rules to avoid generating static rules for the Ethernet interface. These rules cause problems when you clone a virtual machine in Azure or Hyper-V:
```
# sudo ln -s /dev/null /etc/udev/rules.d/75-persistent-net-generator.rules

# sudo rm -f /etc/udev/rules.d/70-persistent-net.rules
```
Ensure that the network service will start at boot time by running the following command:
```
# chkconfig network on
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# subscription-manager register --auto-attach --username=XXX --password=XXX
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this configuration, open /boot/grub/menu.lst in a text editor, and ensure that the default kernel includes the following parameters:
```
console=ttyS0 earlyprintk=ttyS0 
```
This will also ensure that all console messages are sent to the first serial port, which can assist Azure support with debugging issues.

In addition, we recommend that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
Add Hyper-V modules to initramfs:

Edit /etc/dracut.conf, and add the following content:
```
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
```
Rebuild initramfs:
```
# dracut -f -v
```
Uninstall cloud-init:
```
# yum remove cloud-init
```
Ensure that the SSH server is installed and configured to start at boot time:
```
# chkconfig sshd on
```
Modify /etc/ssh/sshd_config to include the following lines:
```
PasswordAuthentication yes
ClientAliveInterval 180
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-6-server-extras-rpms
```
Install the Azure Linux Agent by running the following command:
```
# yum install WALinuxAgent

# chkconfig waagent on
```
The Azure Linux Agent can automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. Note that the local resource disk is a temporary disk, and it might be emptied if the virtual machine is deprovisioned. After you install the Azure Linux Agent in the previous step, modify the following parameters in /etc/waagent.conf appropriately:
```
ResourceDisk.Format=y
ResourceDisk.Filesystem=ext4
ResourceDisk.MountPoint=/mnt/resource
ResourceDisk.EnableSwap=y
ResourceDisk.SwapSizeMB=2048    ## NOTE: set this to whatever you need it to be.
```
Unregister the subscription (if necessary) by running the following command:
```
# subscription-manager unregister
```

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

# Note: if you are migrating a specific virtual machine and don't wish to create a generalized image,
# skip the deprovision step
# sudo rm -rf /var/lib/waagent/
# sudo rm -f /var/log/waagent.log

# waagent -force -deprovision+user
# rm -f ~/.bash_history


# export HISTSIZE=0

# logout

Shut down the virtual machine in KVM.
Convert the qcow2 image to the VHD format.

Note

There is a known bug in qemu-img versions >=2.2.1 that results in an improperly formatted VHD. The issue has been fixed in QEMU 2.6. It is recommended to use either qemu-img 2.2.0 or lower, or update to 2.6 or higher. Reference: https://bugs.launchpad.net/qemu/+bug/1490611.

First convert the image to raw format:
```
# qemu-img convert -f qcow2 -O raw rhel-6.9.qcow2 rhel-6.9.raw
```
Make sure that the size of the raw image is aligned with 1 MB. Otherwise, round up the size to align with 1 MB:
```
# MB=$((1024*1024))
# size=$(qemu-img info -f raw --output json "rhel-6.9.raw" | \
  gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')

# rounded_size=$((($size/$MB + 1)*$MB))
# qemu-img resize rhel-6.9.raw $rounded_size
```
Convert the raw disk to a fixed-sized VHD:
```
# qemu-img convert -f raw -o subformat=fixed -O vpc rhel-6.9.raw rhel-6.9.vhd
```
Or, with qemu version 2.6+ include the force_size option:
```
# qemu-img convert -f raw -o subformat=fixed,force_size -O vpc rhel-6.9.raw rhel-6.9.vhd
```

RHEL 7 using KVM

Download the KVM image of RHEL 7 from the Red Hat website. This procedure uses RHEL 7 as the example.
Set a root password.

Generate an encrypted password, and copy the output of the command:
```
# openssl passwd -1 changeme
```
Set a root password with guestfish:
```
# guestfish --rw -a <image-name>
> <fs> run
> <fs> list-filesystems
> <fs> mount /dev/sda1 /
> <fs> vi /etc/shadow
> <fs> exit
```
Change the second field of root user from "!!" to the encrypted password.
Create a virtual machine in KVM from the qcow2 image. Set the disk type to qcow2, and set the virtual network interface device model to virtio. Then, start the virtual machine, and sign in as root.
Create or edit the /etc/sysconfig/network file, and add the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```

Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
PERSISTENT_DHCLIENT=yes
NM_CONTROLLED=yes

Ensure that the network service will start at boot time by running the following command:
```
# sudo systemctl enable network
```
Register your Red Hat subscription to enable installation of packages from the RHEL repository by running the following command:
```
# subscription-manager register --auto-attach --username=XXX --password=XXX
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this configuration, open /etc/default/grub in a text editor, and edit the GRUB_CMDLINE_LINUX parameter. For example:
```
GRUB_CMDLINE_LINUX="console=ttyS0 earlyprintk=ttyS0 net.ifnames=0"
```
This command also ensures that all console messages are sent to the first serial port, which can assist Azure support with debugging issues. The command also turns off the new RHEL 7 naming conventions for NICs. In addition, we recommend that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
After you are done editing /etc/default/grub, run the following command to rebuild the grub configuration:
```
# grub2-mkconfig -o /boot/grub2/grub.cfg
```
Add Hyper-V modules into initramfs.

Edit /etc/dracut.conf and add content:
```
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
```
Rebuild initramfs:
```
# dracut -f -v
```
Uninstall cloud-init:
```
# yum remove cloud-init
```
Ensure that the SSH server is installed and configured to start at boot time:
```
# systemctl enable sshd
```
Modify /etc/ssh/sshd_config to include the following lines:
```
PasswordAuthentication yes
ClientAliveInterval 180
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-7-server-extras-rpms
```
Install the Azure Linux Agent by running the following command:
```
# yum install WALinuxAgent
```
Enable the waagent service:
```
# systemctl enable waagent.service
```
Install cloud-init Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 12, 'Install cloud-init to handle the provisioning.'
Swap configuration

Don't create swap space on the operating system disk. Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 13, 'Swap configuration'
Unregister the subscription (if necessary) by running the following command:
```
# subscription-manager unregister
```
Deprovision

Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 15, 'Deprovision'
Shut down the virtual machine in KVM.
Convert the qcow2 image to the VHD format.

Note

There is a known bug in qemu-img versions >=2.2.1 that results in an improperly formatted VHD. The issue has been fixed in QEMU 2.6. It is recommended to use either qemu-img 2.2.0 or lower, or update to 2.6 or higher. Reference: https://bugs.launchpad.net/qemu/+bug/1490611.

First convert the image to raw format:
```
# qemu-img convert -f qcow2 -O raw rhel-7.4.qcow2 rhel-7.4.raw
```
Make sure that the size of the raw image is aligned with 1 MB. Otherwise, round up the size to align with 1 MB:
```
# MB=$((1024*1024))
# size=$(qemu-img info -f raw --output json "rhel-7.4.raw" | \
  gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')

# rounded_size=$((($size/$MB + 1)*$MB))
# qemu-img resize rhel-7.4.raw $rounded_size
```
Convert the raw disk to a fixed-sized VHD:
```
# qemu-img convert -f raw -o subformat=fixed -O vpc rhel-7.4.raw rhel-7.4.vhd
```
Or, with qemu version 2.6+ include the force_size option:
```
# qemu-img convert -f raw -o subformat=fixed,force_size -O vpc rhel-7.4.raw rhel-7.4.vhd
```

VMware

This section shows you how to prepare a RHEL 6 or RHEL 7 distro from VMware.

Prerequisites

This section assumes that you have already installed a RHEL virtual machine in VMware. For details about how to install an operating system in VMware, see VMware Guest Operating System Installation Guide.

When you install the Linux operating system, we recommend that you use standard partitions rather than LVM, which is often the default for many installations. This will avoid LVM name conflicts with cloned virtual machine, particularly if an operating system disk ever needs to be attached to another virtual machine for troubleshooting. LVM or RAID can be used on data disks if preferred.
Don't configure a swap partition on the operating system disk. You can configure the Linux agent to create a swap file on the temporary resource disk. You can find more information about this in the steps that follow.
When you create the virtual hard disk, select Store virtual disk as a single file.

RHEL 6 using VMware

In RHEL 6, NetworkManager can interfere with the Azure Linux agent. Uninstall this package by running the following command:
```
# sudo rpm -e --nodeps NetworkManager
```
Create a file named network in the /etc/sysconfig/ directory that contains the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```
Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:
```
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
```
Move (or remove) the udev rules to avoid generating static rules for the Ethernet interface. These rules cause problems when you clone a virtual machine in Azure or Hyper-V:
```
# sudo ln -s /dev/null /etc/udev/rules.d/75-persistent-net-generator.rules

# sudo rm -f /etc/udev/rules.d/70-persistent-net.rules
```
Ensure that the network service will start at boot time by running the following command:
```
# sudo chkconfig network on
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# sudo subscription-manager register --auto-attach --username=XXX --password=XXX
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-6-server-extras-rpms
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this, open /etc/default/grub in a text editor, and edit the GRUB_CMDLINE_LINUX parameter. For example:
```
GRUB_CMDLINE_LINUX="console=ttyS0 earlyprintk=ttyS0"
```
This will also ensure that all console messages are sent to the first serial port, which can assist Azure support with debugging issues. In addition, we recommend that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
Add Hyper-V modules to initramfs:

Edit /etc/dracut.conf, and add the following content:
```
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
```
Rebuild initramfs:
```
# dracut -f -v
```
Ensure that the SSH server is installed and configured to start at boot time, which is usually the default. Modify /etc/ssh/sshd_config to include the following line:
```
ClientAliveInterval 180
```
Install the Azure Linux Agent by running the following command:
```
# sudo yum install WALinuxAgent

# sudo chkconfig waagent on
```
Don't create swap space on the operating system disk.

The Azure Linux Agent can automatically configure swap space by using the local resource disk that is attached to the virtual machine after the virtual machine is provisioned on Azure. Note that the local resource disk is a temporary disk, and it might be emptied if the virtual machine is deprovisioned. After you install the Azure Linux Agent in the previous step, modify the following parameters in /etc/waagent.conf appropriately:
```
ResourceDisk.Format=y
ResourceDisk.Filesystem=ext4
ResourceDisk.MountPoint=/mnt/resource
ResourceDisk.EnableSwap=y
ResourceDisk.SwapSizeMB=2048    ## NOTE: set this to whatever you need it to be.
```
Unregister the subscription (if necessary) by running the following command:
```
# sudo subscription-manager unregister
```

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

# Note: if you are migrating a specific virtual machine and don't wish to create a generalized image,
# skip the deprovision step
# sudo rm -rf /var/lib/waagent/
# sudo rm -f /var/log/waagent.log

# waagent -force -deprovision+user
# rm -f ~/.bash_history


# export HISTSIZE=0

# logout

Shut down the virtual machine, and convert the VMDK file to a .vhd file.

Note

There is a known bug in qemu-img versions >=2.2.1 that results in an improperly formatted VHD. The issue has been fixed in QEMU 2.6. It is recommended to use either qemu-img 2.2.0 or lower, or update to 2.6 or higher. Reference: https://bugs.launchpad.net/qemu/+bug/1490611.

First convert the image to raw format:
```
# qemu-img convert -f vmdk -O raw rhel-6.9.vmdk rhel-6.9.raw
```
Make sure that the size of the raw image is aligned with 1 MB. Otherwise, round up the size to align with 1 MB:
```
# MB=$((1024*1024))
# size=$(qemu-img info -f raw --output json "rhel-6.9.raw" | \
  gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')

# rounded_size=$((($size/$MB + 1)*$MB))
# qemu-img resize rhel-6.9.raw $rounded_size
```
Convert the raw disk to a fixed-sized VHD:
```
# qemu-img convert -f raw -o subformat=fixed -O vpc rhel-6.9.raw rhel-6.9.vhd
```
Or, with qemu version 2.6+ include the force_size option:
```
# qemu-img convert -f raw -o subformat=fixed,force_size -O vpc rhel-6.9.raw rhel-6.9.vhd
```

RHEL 7 using VMware

Create or edit the /etc/sysconfig/network file, and add the following text:
```
NETWORKING=yes
HOSTNAME=localhost.localdomain
```

Create or edit the /etc/sysconfig/network-scripts/ifcfg-eth0 file, and add the following text:

DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
PERSISTENT_DHCLIENT=yes
NM_CONTROLLED=yes

Ensure that the network service will start at boot time by running the following command:
```
# sudo systemctl enable network
```
Register your Red Hat subscription to enable the installation of packages from the RHEL repository by running the following command:
```
# sudo subscription-manager register --auto-attach --username=XXX --password=XXX
```
Modify the kernel boot line in your grub configuration to include additional kernel parameters for Azure. To do this modification, open /etc/default/grub in a text editor, and edit the GRUB_CMDLINE_LINUX parameter. For example:
```
GRUB_CMDLINE_LINUX="console=ttyS0 earlyprintk=ttyS0 net.ifnames=0"
```
This configuration also ensures that all console messages are sent to the first serial port, which can assist Azure support with debugging issues. It also turns off the new RHEL 7 naming conventions for NICs. In addition, we recommend that you remove the following parameters:
```
rhgb quiet crashkernel=auto
```
Graphical and quiet boot aren't useful in a cloud environment where we want all the logs to be sent to the serial port. You can leave the crashkernel option configured if desired. Note that this parameter reduces the amount of available memory in the virtual machine by 128 MB or more, which might be problematic on smaller virtual machine sizes.
After you are done editing /etc/default/grub, run the following command to rebuild the grub configuration:
```
# sudo grub2-mkconfig -o /boot/grub2/grub.cfg
```
Add Hyper-V modules to initramfs.

Edit /etc/dracut.conf, add content:
```
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "
```
Rebuild initramfs:
```
# dracut -f -v
```
Ensure that the SSH server is installed and configured to start at boot time. This setting is usually the default. Modify /etc/ssh/sshd_config to include the following line:
```
ClientAliveInterval 180
```
The WALinuxAgent package, WALinuxAgent-<version>, has been pushed to the Red Hat extras repository. Enable the extras repository by running the following command:
```
# subscription-manager repos --enable=rhel-7-server-extras-rpms
```

Install the Azure Linux Agent by running the following command:

# sudo yum install WALinuxAgent

# sudo systemctl enable waagent.service

Install cloud-init

Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 12, 'Install cloud-init to handle the provisioning.'
Swap configuration

Don't create swap space on the operating system disk. Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 13, 'Swap configuration'
If you want to unregister the subscription, run the following command:
```
# sudo subscription-manager unregister
```
Deprovision

Follow the steps in 'Prepare a RHEL 7 virtual machine from Hyper-V Manager', step 15, 'Deprovision'
Shut down the virtual machine, and convert the VMDK file to the VHD format.

Note

There is a known bug in qemu-img versions >=2.2.1 that results in an improperly formatted VHD. The issue has been fixed in QEMU 2.6. It is recommended to use either qemu-img 2.2.0 or lower, or update to 2.6 or higher. Reference: https://bugs.launchpad.net/qemu/+bug/1490611.

First convert the image to raw format:
```
# qemu-img convert -f vmdk -O raw rhel-7.4.vmdk rhel-7.4.raw
```
Make sure that the size of the raw image is aligned with 1 MB. Otherwise, round up the size to align with 1 MB:
```
# MB=$((1024*1024))
# size=$(qemu-img info -f raw --output json "rhel-7.4.raw" | \
  gawk 'match($0, /"virtual-size": ([0-9]+),/, val) {print val[1]}')

# rounded_size=$((($size/$MB + 1)*$MB))
# qemu-img resize rhel-7.4.raw $rounded_size
```
Convert the raw disk to a fixed-sized VHD:
```
# qemu-img convert -f raw -o subformat=fixed -O vpc rhel-7.4.raw rhel-7.4.vhd
```
Or, with qemu version 2.6+ include the force_size option:
```
# qemu-img convert -f raw -o subformat=fixed,force_size -O vpc rhel-7.4.raw rhel-7.4.vhd
```

Kickstart file

This section shows you how to prepare a RHEL 7 distro from an ISO using a kickstart file.

RHEL 7 from a kickstart file

Create a kickstart file that includes the following content, and save the file. For details about kickstart installation, see the Kickstart Installation Guide.

# Kickstart for provisioning a RHEL 7 Azure VM

# System authorization information
  auth --enableshadow --passalgo=sha512

# Use graphical install
text

# Don't run the Setup Agent on first boot
firstboot --disable

# Keyboard layouts
keyboard --vckeymap=us --xlayouts='us'

# System language
lang en_US.UTF-8

# Network information
network  --bootproto=dhcp

# Root password
rootpw --plaintext "to_be_disabled"

# System services
services --enabled="sshd,waagent,NetworkManager"

# System timezone
timezone Etc/UTC --isUtc --ntpservers 0.rhel.pool.ntp.org,1.rhel.pool.ntp.org,2.rhel.pool.ntp.org,3.rhel.pool.ntp.org

# Partition clearing information
clearpart --all --initlabel

# Clear the MBR
zerombr

# Disk partitioning information
part /boot --fstype="xfs" --size=500
part / --fstyp="xfs" --size=1 --grow --asprimary

# System bootloader configuration
bootloader --location=mbr

# Firewall configuration
firewall --disabled

# Enable SELinux
selinux --enforcing

# Don't configure X
skipx

# Power down the machine after install
poweroff

%packages
@base
@console-internet
chrony
sudo
parted
-dracut-config-rescue

%end

%post --log=/var/log/anaconda/post-install.log

#!/bin/bash

# Register Red Hat Subscription
subscription-manager register --username=XXX --password=XXX --auto-attach --force

# Install latest repo update
yum update -y

# Enable extras repo
subscription-manager repos --enable=rhel-7-server-extras-rpms

# Install WALinuxAgent
yum install -y WALinuxAgent

# Unregister Red Hat subscription
subscription-manager unregister

# Enable waaagent at boot-up
systemctl enable waagent

# Install cloud-init
yum install -y cloud-init cloud-utils-growpart gdisk hyperv-daemons

# Configure waagent for cloud-init
sed -i 's/Provisioning.Agent=auto/Provisioning.Agent=cloud-init/g' /etc/waagent.conf
sed -i 's/ResourceDisk.Format=y/ResourceDisk.Format=n/g' /etc/waagent.conf
sed -i 's/ResourceDisk.EnableSwap=y/ResourceDisk.EnableSwap=n/g' /etc/waagent.conf

echo "Adding mounts and disk_setup to init stage"
sed -i '/ - mounts/d' /etc/cloud/cloud.cfg
sed -i '/ - disk_setup/d' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - mounts' /etc/cloud/cloud.cfg
sed -i '/cloud_init_modules/a\\ - disk_setup' /etc/cloud/cloud.cfg

# Disable the root account
usermod root -p '!!'

# Configure swap using cloud-init
echo 'DefaultEnvironment="CLOUD_CFG=/etc/cloud/cloud.cfg.d/00-azure-swap.cfg"' >> /etc/systemd/system.conf
cat > /etc/cloud/cloud.cfg.d/00-azure-swap.cfg << EOF
#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.device-timeout=2,x-systemd.requires=cloud-init.service", "0", "0"]
EOF

# Set the cmdline
sed -i 's/^\(GRUB_CMDLINE_LINUX\)=".*"$/\1="console=tty1 console=ttyS0 earlyprintk=ttyS0"/g' /etc/default/grub

# Enable SSH keepalive
sed -i 's/^#\(ClientAliveInterval\).*$/\1 180/g' /etc/ssh/sshd_config

# Build the grub cfg
grub2-mkconfig -o /boot/grub2/grub.cfg

# Configure network
cat << EOF > /etc/sysconfig/network-scripts/ifcfg-eth0
DEVICE=eth0
ONBOOT=yes
BOOTPROTO=dhcp
TYPE=Ethernet
USERCTL=no
PEERDNS=yes
IPV6INIT=no
PERSISTENT_DHCLIENT=yes
NM_CONTROLLED=yes
EOF

# Deprovision and prepare for Azure if you are creating a generalized image
sudo cloud-init clean --logs --seed
sudo rm -rf /var/lib/cloud/
sudo rm -rf /var/lib/waagent/
sudo rm -f /var/log/waagent.log

sudo waagent -force -deprovision+user
rm -f ~/.bash_history
export HISTSIZE=0

%end

Place the kickstart file where the installation system can access it.
In Hyper-V Manager, create a new virtual machine. On the Connect Virtual Hard Disk page, select Attach a virtual hard disk later, and complete the New Virtual Machine Wizard.
Open the virtual machine settings:

a. Attach a new virtual hard disk to the virtual machine. Make sure to select VHD Format and Fixed Size.

b. Attach the installation ISO to the DVD drive.

c. Set the BIOS to boot from CD.
Start the virtual machine. When the installation guide appears, press Tab to configure the boot options.
Enter inst.ks=<the location of the kickstart file> at the end of the boot options, and press Enter.
Wait for the installation to finish. When it's finished, the virtual machine will be shut down automatically. Your Linux VHD is now ready to be uploaded to Azure.

Known issues

The Hyper-V driver couldn't be included in the initial RAM disk when using a non-Hyper-V hypervisor

In some cases, Linux installers might not include the drivers for Hyper-V in the initial RAM disk (initrd or initramfs) unless Linux detects that it is running in a Hyper-V environment.

When you're using a different virtualization system (that is, VirtualBox, Xen, etc.) to prepare your Linux image, you might need to rebuild initrd to ensure that at least the hv_vmbus and hv_storvsc kernel modules are available on the initial RAM disk. This is a known issue at least on systems that are based on the upstream Red Hat distribution.

To resolve this issue, add Hyper-V modules to initramfs and rebuild it:

Edit /etc/dracut.conf, and add the following content:

add_drivers+=" hv_vmbus hv_netvsc hv_storvsc "

Rebuild initramfs:

# dracut -f -v

For more details, see the information about rebuilding initramfs.

Next steps

You're now ready to use your Red Hat Enterprise Linux virtual hard disk 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.
For more details about the hypervisors that are certified to run Red Hat Enterprise Linux, see the Red Hat website.
To learn more about using production-ready RHEL BYOS images, go to the documentation page for BYOS.

Prepare a Red Hat-based virtual machine for Azure

Hyper-V Manager

Prerequisites

RHEL 6 using Hyper-V Manager

RHEL 7 using Hyper-V Manager

RHEL 8 using Hyper-V Manager

KVM

RHEL 6 using KVM

RHEL 7 using KVM

VMware

Prerequisites

RHEL 6 using VMware

RHEL 7 using VMware

Kickstart file

RHEL 7 from a kickstart file

Known issues

The Hyper-V driver couldn't be included in the initial RAM disk when using a non-Hyper-V hypervisor

Next steps

Feedback

Additional resources

Additional resources