Virtual Machine Setup Guide

We’ll be using Arch Linux virtual machines (VMs) in CS 521. Arch Linux is a simple distribution that gives us the opportunity to configure our virtual machines exactly as we want. For your reference, the Arch Linux Wiki has a wealth of information on configuring the system, swapping out components, and installing a wide variety of software, but this guide will get you up and running.

In this lab, you’ll create a virtual machine using Kernel-based Virtual Machine (KVM) virtualization in Linux.

Virtual Machine Setup

One of our goals in this class is to get more familiar with Linux (and Unix) systems, particularly with the command line interface (CLI). Instead of giving each student a Linux workstation to use over the course of the semester, we’ll use virtual machines. After all, virtualized infrastructure has revolutionized the computing landscape; rather than maintaining large datacenters with thousands of power-hungry servers, companies can start and stop virtual machines as needed to scale their infrastructure in or out as required.

KVM is a virtualization module that allows Linux to act as a hypervisor, or software component that supervises virtual machines. In VM terminology, you have two types of systems:

We will use our VM host gojira to create a VM guest for each student in this lab.

Logging into the VM Host

Dust off your USF CS credentials and ssh into our jump host, stargate.cs.usfca.edu. Once logged in you can proceed to ssh to our VM host, gojira:

# Get to the CS network:
$ ssh mmalensek@stargate.cs.usfca.edu

# Log in to the VM host:
$ ssh mmalensek@gojira

# Let's see who else is logged in:
$ finger
Login      Name               Tty      Idle  Login Time   
afedosov   Alex Fedosov       pts/0    4:04  Jan  9 12:20 
mmalensek  Matthew Malensek   pts/1          Jan  9 17:31 
# (This output will probably be a bit more exciting once classes start)

All of our VMs will be hosted on a single server (gojira), which has 64 hardware threads (32 cores) and 128 GB of RAM. You will be able to log into the VM host to see all the VMs running.

Creating a new Virtual Machine

Before you start running commands, take a step back and determine the following:

Virtualization functionality is provided by the libvirt toolkit. We’ll use the virt-install command to set up our VM. Note that in the following example, the backslash (\) denotes a command continuation, a way of breaking one very long command line into multiple lines. You will need to tweak the command a bit to customize it for your own VM; see the explanation below for details.

TIP: if you’re about to paste the following into a text editor to modify, make sure it is in plain text mode! If it isn’t, it’ll make replacements with special characters that look almost exactly like normal characters but won’t work in your terminal.

$ virt-install \
    --name=VMNAME \
    --cpu host --vcpus=4 \
    --memory=2000 \
    --disk=/raid/$(whoami)/VMNAME.qcow2,size=32 \
    --cdrom=/home2/iso/archlinux-????????.iso \
    --net model=virtio,bridge=virbr0,mac='52:54:00:CA:FE:VMIDHEX' \
    --boot useserial=on \
    --console pty,target_type=serial \
    --graphics none \
    --os-variant=archlinux \
    --noautoconsole

Be sure to update:

You can leave the rest of the command line flags as shown above. They do the following:

If you would like to check out all the command line flags available for the virt-install utility, take a look at the man pages: man virt-install.

As long as virt-install succeeded, you should be ready to set up your OS. To verify, run virsh list:

# Note that without the --all flag, only running VMs will be shown.
# If your VM gets shut down later, you'll want to remember to pass
# this flag so you can check its status.
$ virsh list --all
 Id    Name                           State
 ----------------------------------------------------
 1     magical-unicorn                running

Great, it’s running! Let’s log in to the console:

virsh console VMNAME

You will see the boot splash screen (it might be nearly unreadable because we’re using an ancient serial console to view the VM’s screen). Hit enter to start the boot process, and after a few seconds you should see a login: prompt. Enter root as the username and you should be dropped into a root shell, ready to configure the system.

NOTE 1: if you need to exit the console for some reason, you can press Control + ] (control and the right square bracket). If you rerun virsh console VMNAME later, you’ll pick up in the same place – your VM keeps running on gojira even if you move on to doing something else.

NOTE 2: if you don’t see anything when you connect to the console, try hitting enter a couple times and then wait.

Installing the OS

At this point, we’ve booted up a Live CD version of Arch Linux. The live CD contains all the standard Unix utilities we need to bootstrap and install the operating system onto our VM’s hard disk. Your VM should already be connected to the network. We will verify this with the ping command:

root@archiso ~ ＃ ls
vm-setup.md
root@archiso ~ ＃ ping google.com
PING google.com (216.58.194.206): 56 data bytes
64 bytes from 216.58.194.206: icmp_seq=0 ttl=57 time=11.457 ms
64 bytes from 216.58.194.206: icmp_seq=1 ttl=57 time=4.017 ms
^C

# (Ctrl + C quits the program -- standard on Unix systems).

Now we need to verify that the IP address our VM received from the DHCP server is correct. To do this, run:

root@archiso ~ ＃ ip address | grep '192\.168\.122'
# This should output something like:
    inet 192.168.122.105/24 brd 192.168.122.255 scope global ens3
# The last number of the IP address should be your 521 ID.

The last number of the IP address MUST be your 521 ID number!. In this case, mine is 105. If this is wrong, then you need to confirm you configured the MAC address correctly in the steps above.

Okay, so our IP is correct and we’re online. We have a live CD running and want to set up a new installation of Linux on our VM’s hard disk. Let’s get started!

Installation Script

We’ll provide a semi-automated script to set up your VM. You can download and run the script directly with the following (make sure you scroll over to see the entire command line):

/bin/bash -c "$(curl -fsSL https://www.cs.usfca.edu/~mmalensek/cs521/schedule/materials/create-vm-1.sh)"

Note that it’s probably never a good idea to do something like this unless you trust the source – the script could contain commands that you don’t want to execute. Do you trust the CS 521 course staff at this point in the semester? Probably not. But at least the commands are running in a VM, not your own development machine.

The script will:

You are responsible for:

Basic Configuration

Once the script finishes, you will see “Preliminary setup complete!” – that’s your cue to start the basic configuration.

First, we need to install some software packages on our new system. Let’s install them with pacman:

[root@archiso /]＃ pacman -Sy \
    base-devel clang gdb git grub inetutils \
    man man-pages nano python rustup vi vim wget

# Note: you can accept the default packages (just press enter) for the
# 'base-devel' meta-package as well as for the 'man' package.

( ... lots of packages install ... )

Make sure you perform this step! Some of the following configuration steps require these packages.

Creating a User Account

# It's a bad idea to always be logged in as root, so let's create our own user
# account with the useradd command. The -m flag creates a home directory for
# the user (/home/<username>).
# *** Remember: replace VMUSERNAME with your usual CS username!! ***
[root@archiso /]＃ useradd -m VMUSERNAME -g wheel

# Set the password for our new user
[root@archiso /]＃ passwd VMUSERNAME
(enter whatever your VMPASSWORD is at the prompt)

# Let's test out the account. Since we're root, we can actually use the
# substitute user (su) command to switch over:
[root@archiso /]＃ su - VMUSERNAME
[VMUSERNAME@archiso ~]$ 

# Now let's make sure we can use sudo:
[VMUSERNAME@archiso ~]$ sudo ls /root
# (Nothing should display. If you get a permission denied error,
# something went wrong and you probably need to retrace your steps.)

# Great, it worked. Let's switch back to root. To do this, we exit from our
# current session back to the original login session.
[VMUSERNAME@archiso ~]$ exit

Setting the Hostname

There are two hard problems in computer science: cache invalidation, naming things, and off-by-one errors. We have to tackle one of these here: naming your VM. The /etc/hostname file contains the hostname of the machine, so let’s create this file from our shell.

[root@archiso /]＃ echo "VMNAME" > /etc/hostname

# When I executed this command, I did the following:
# *** You should come up with your own name, though!!! ***
[root@archiso /]＃ echo "magical-unicorn" > /etc/hostname

Network Configuration

One of the last things we need to do is set up the network so we (1) assign an IP address to the VM on boot, and (2) access our VM remotely with ssh so we don’t need to use the console.

[root@archiso /]＃ systemctl enable dhcpcd
Created symlink /etc/systemd/system/multi-user.target.wants/dhcpcd.service → /usr/lib/systemd/system/dhcpcd.service.

[root@archiso /]＃ systemctl enable sshd
Created symlink /etc/systemd/system/multi-user.target.wants/sshd.service → /usr/lib/systemd/system/sshd.service.

Alright, we should be all set with the network now.

Finishing Up

Once you’ve created a user account, set the hostname, and configured the network, you are done! Run the exit command to finish the installation process.

Once the installation is over your VM will shut down, so the first thing you’ll want to do is start it back up. To do this, use virsh start:

[gojira:~]$ virsh list --all
 Id    Name                           State
 ----------------------------------------------------
  8     magical-unicorn               shut off

[gojira:~]$ virsh start magical-unicorn
Domain magical-unicorn started

If you have issues connecting to your VM, a good first step is to check to make sure it’s running.

If everything went well, you should be able to ssh to the VM’s IP address from gojira. For instance, if my CS 521 ID is 105, I would do the following:

[mmalensek@gojira ~]$ ssh mmalensek@192.168.122.105

If you can log in, congratulations! You’ve brought a brand new VM into the world! Feel free to explore and exit when you are ready to log off.

If the ssh command did not work, double check that your IP address is correct. If it is, you can try running virsh console VMNAME to see if you can log in to the console directly and then contact the course staff for help.