3.7. Preparing a virtual machine for Azure deployment

Procedure

1. Log in and register the VM to enable the Red Hat Enterprise Linux (RHEL) repository:

   # subscription-manager register
   
   Installed Product Current Status:
   Product Name: Red Hat Enterprise Linux for x86_64
   Status: Subscribed

2. Install the cloud-init and hyperv-daemons packages:

   # dnf install cloud-init hyperv-daemons -y

3. Create the cloud-init configuration files and edit them to offer integration with Azure services:

   1. To enable logging to the Hyper-V Data Exchange Service (KVP), edit the /etc/cloud/cloud.cfg.d/10-azure-kvp.cfg file and append the following lines:

      reporting:
          logging:
              type: log
          telemetry:
              type: hyperv

   2. To add the Azure datasource, edit the /etc/cloud/cloud.cfg.d/91-azure_datasource.cfg file and append the following lines:

      datasource_list: [ Azure ]
      datasource:
          Azure:
              apply_network_config: False

   3. To configure swap space on the ephemeral disk, create the /etc/cloud/cloud.cfg.d/00-azure-swap.cfg configuration file and add the following lines to that file.

      重要

      The ephemeral disk is temporary storage. Therefore, data stored on it, including swap space, is lost when the VM is deallocated or moved. Use the ephemeral disk only for temporary data such as swap space.

      #cloud-config
      disk_setup:
        ephemeral0:
          table_type: gpt
          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", "0", "0"]

4. To block automatic loading of specific kernel modules, edit the /etc/modprobe.d/blocklist.conf file and append the following lines:

   blacklist nouveau
   blacklist lbm-nouveau
   blacklist floppy
   blacklist amdgpu
   blacklist skx_edac
   blacklist intel_cstate

5. Modify udev network device rules:

   1. If present, remove the following persistent network device rules:

      # rm -f /etc/udev/rules.d/70-persistent-net.rules
      # rm -f /etc/udev/rules.d/75-persistent-net-generator.rules
      # rm -f /etc/udev/rules.d/80-net-name-slot-rules

   2. To ensure working of accelerated networking on Azure, edit the /etc/udev/rules.d/68-azure-sriov-nm-unmanaged.rules new network device rule and append the following line:

      SUBSYSTEM=="net", DRIVERS=="hv_pci", ACTION=="add", ENV{NM_UNMANAGED}="1"

6. Set the sshd service to start automatically:

   # systemctl enable sshd
   # systemctl is-enabled sshd

7. Modify kernel boot parameters:

   1. Update the GRUB_TIMEOUT parameter value in the /etc/default/grub file:

      GRUB_TIMEOUT=10

   2. Remove the following option from the end of the GRUB_CMDLINE_LINUX line, if present:

      rhgb quiet

   3. Update the /etc/default/grub file with the following configuration details:

      GRUB_CMDLINE_LINUX="loglevel=3 crashkernel=auto console=tty1 console=ttyS0 earlyprintk=ttyS0 rootdelay=300"
      GRUB_TIMEOUT_STYLE=countdown
      GRUB_TERMINAL="serial console"
      GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

      注意

      By adding the elevator=none option to the end of the GRUB_CMDLINE_LINUX line disables the I/O scheduler entirely. This option processes I/O requests according to the order of execution, without optimizing disk performance. With elevator=none on:

      • Hard disk drive (HDD): Performance and throughput decreases, therefore not suitable for running workloads.
      • Solid state drive (SSD): High performance and low latency, therefore suitable for running workloads.

   4. Regenerate the grub.cfg file:

      • On a BIOS-based machine:

        # grub2-mkconfig -o /boot/grub2/grub.cfg --update-bls-cmdline

      • On a UEFI-based machine:

        # grub2-mkconfig -o /boot/grub2/grub.cfg --update-bls-cmdline

        警告

        The path to rebuild grub.cfg is same for both BIOS and UEFI based machines. Original grub.cfg is present at BIOS path only. The UEFI path has a stub file that must not be modified or recreated using grub2-mkconfig command.

        If your system uses a non-default location for grub.cfg, adjust the command accordingly.

8. Configure the Windows Azure Linux Agent (WALinuxAgent):

   1. Install and enable the WALinuxAgent package:

      # dnf install WALinuxAgent -y
      # systemctl enable waagent

   2. To disable swap configuration in WALinuxAgent (required when using cloud-init to manage swap), edit the following lines in the /etc/waagent.conf file:

      Provisioning.DeleteRootPassword=y
      ResourceDisk.Format=n
      ResourceDisk.EnableSwap=n
      ResourceDisk.SwapSizeMB=0

      注意

      By disabling swap in WALinuxAgent, you enable cloud-init to manage the swap configuration on the ephemeral disk.

9. Prepare the VM for Azure provisioning:

   1. Unregister the VM from Red Hat Subscription Manager:

      # subscription-manager unregister

   2. Clean up the existing provisioning details:

      # waagent -force -deprovision

      注意

      This command generates warnings as Azure automatically handles the VM provisioning.

   3. Clear the shell history and shut down the VM:

      # export HISTSIZE=0
      # poweroff