Virtualization (Part 2)

On my host machine, I'm using KVM for AMD:

$ lsmod | grep -i kvm

kvm_amd 200704 0

kvm 1343488 1 kvm_amd

irqbypass 12288 1 kvm

ccp 159744 2 i2c_designware_platform,kvm_amd

Check the CPU extensions on your host system:

$ grep ^flags /proc/cpuinfo | grep vmx

If you get a response, then you are most likely running on a host system that will support virtualization and has an Intel chip.

Perform another check of the CPU extensions on your system:

$ grep ^flags /proc/cpuinfo | grep svm

If you get a response, then you are most likely running on a host system that will support virtualization and has an AMD chip.

Perform one more check of the CPU extensions:

$ grep ^flags /proc/cpuinfo | grep -i hypervisor

If you get a response, then most likely you are running your Linux system as a guest VM.

You may find the following two types of files for your VM: Open Virtualization Format (OVF) file or Open Virtualization Application (OVA) file.

You can create a clone of the VM or a template, however, the template is not bootable.

Items to check after cloning a VM

• Remove and regenerate the D-BUS Machine ID from /var/lib/dbus/machine-id and the Machine ID from /etc/machine-id. /var/lib/dbus/machine-id is actually supposed to be a symbolic link to /etc/machine-id. This ensures the system has one single "source of truth" for its identity. /var/lib/dbus/machine-id may not be found in every system. Determine if you could regenerate an ID number to use as the D-bus machine's ID, by typing which dbus-uuidgen.

• Host name

• NIC MAC addresses

• NIC static IP addresses, if any

• Universally Unique Identifiers (UUID)

• Regenerate SSH Host Keys: If you don't do this, every clone will share the same "fingerprint," which is a security risk. sudo rm -f /etc/ssh/ssh_host_* ; sudo ssh-keygen -A ; sudo systemctl restart ssh . Once you do this, the next time you try to SSH into this VM from, let's say, your physical computer, you will see a WARNING:

  @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  @ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

  This is normal. Your computer remembers the old key associated with that IP address. You need to clear that old entry on your local machine (not the cloned VM) with:

  ssh-keygen -R [IP_ADDRESS_OF_VM]

Cloud-init

It is the industry-standard open-source tool for initializing and customizing Linux/Unix virtual machines (VMs) in cloud computing. You can use it to automatically generate all the items after cloning a VM. When you launch a VM, Cloud-init looks for a special file called user-data (usually a YAML file). Every clone gets a unique UUID, unique SSH keys, and a unique hostname automatically.

For more information on Virtualization, check Part 1.