305-300 Exam Dumps : LPIC-3: Virtualization and Containerization - Exam 305, version 3.0

The lxc-attach command allows the user to start a new process within a running LXC container12. It takes the name of the container as an argument and optionally a command to execute inside the container. If no command is specified, it creates a new shell inside the container1. For example, to list all the files in the home directory of a container named myContainer, one can use:

lxc-attach -n myContainer – ls -lh /home

References:

1: Executing a command inside a running LXC - Unix & Linux Stack Exchange

 The Linux kernel module that must be loaded in order to use QEMU with hardware virtualization extensions is KVM (Kernel-based Virtual Machine). KVM is a full virtualization solution that allows a user space program (such as QEMU) to utilize the hardware virtualization features of various processors (such as Intel VT or AMD-V). KVM consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, kvm-intel.ko or kvm-amd.ko. KVM must be loaded into the kernel of the host system in order to use the virtualization extensions of the host system’s CPU. This enables QEMU to run multiple virtual machines with unmodified Linux or Windows images, each with private virtualized hardware. KVM is integrated with QEMU, so there is no need to load it into the kernel of each virtual machine or the first virtual machine. KVM also does not require paravirtualization, which is a technique that modifies the guest operating system to communicate directly with the hypervisor, bypassing the emulation layer. References:

Features/KVM - QEMU

Kernel-based Virtual Machine

KVM virtualization on Red Hat Enterprise Linux 8 (2023)

Cloud-init is a tool that processes configurations and runs through five stages during the initial boot of Linux VMs in a cloud. It allows users to customize a Linux VM as it boots for the first time, by applying user data to the instance. User data can include scripts, commands, packages, files, users, groups, SSH keys, and more. Cloud-init can also interact with various cloud platforms and services, such as Azure, AWS, OpenStack, and others. The purpose of cloud-init is to prepare the generic image of an laaS instance to fit a specific instance’s configuration, such as hostname, network, security, and application settings. References:

Cloud-init - The standard for customising cloud instances

Understanding cloud-init - Azure Virtual Machines

Tutorial - Customize a Linux VM with cloud-init in Azure - Azure Virtual Machines