OPS235 Lab 2 - CentOS7 - HD2
Contents
LAB PREPARATION
Purpose / Objectives of Lab2
In this lab, you will create 3 virtual machines within your host machine using another virtualization program called KVM. These VMs will be used throughout the remainder of this course to learn how to administer them (installing software, managing services, networking, etc).
While you are performing this lab, it is recommended to generally note the major differences in the different installation methods, and which method you prefer to use if you were a Linux system administrator in charge of installing many Linux distributions for an organization.
Main Objectives
- Installing additional Virtualization Software on your c7host machine (KVM)
- Create 3 separate VMs (virtual machines) using different installation methods:
- centos1: Network Centos Installation (Graphical)
- centos2: Network Centos Installation (minimal install - CLI only)
- centos3: Network Centos Installation with Kickstart configuration file (CLI only)
- Manipulate virtual machines by CLI (virsh)
- Properly backup VM images and backup VM configuration files
- Create and run Bash Shell scripts to automatically create a post-install report for an installed VM.
Minimum Required Materials |
Linux Command Reference | ||||
Virtualization |
Miscellaneous |
Matrix Online Tutorials:
|
INVESTIGATION 1: SETUP FOR VIRTUAL MACHINES
Part 1: Install KVM Virtualization Application
We will now install the KVM package in order to create our VMs. We will also be starting several services (including iptables) and disabling the firewalld service. We will learn more about managing firewalls using iptables in lab6.
- Perform the following steps:
- Log into your c7host machine, and switch to root user.
- perform a software update on your c7host VM by issuing the following command:
yum update
- As root, install the virtualization software by issuing the command:
yum install qemu-kvm qemu-img virt-manager libvirt libvirt-python \
python-virtinst libvirt-client virt-install virt-viewer bridge-utils - Restart your c7host virtual machine. If you fail to do this, you may experience virtualization network problems.
- Start the virtualization service:
systemctl start libvirtd
NOTE: The most recent variants of Centos and Fedora are using a service called firewalld that is intended to replace iptables, however the iptables service is still in relatively common usage. In this course we will concentrate on iptables. - To Disable firewalld issue the following commands:
systemctl disable firewalld
systemctl stop firewalld
- To install and enable the IPTables services, issue the following commands:
yum install iptables-services
systemctl enable iptables
systemctl start iptables
- Start the graphical tool by selecting the menu options Applications>System Tools>Virtual Machine Manager or by typing the command
virt-manager
- You will be learning in the next investigation to perform several different type of CENTOS Linux installs.
Answer the INVESTIGATION 1 observations / questions in your lab log book.
INVESTIGATION 2: INSTALL VIRTUAL MACHINES (KVM)
Part 1: Installing VM from a Network (Graphical)
- VM Details:
- VM Name (and hostname): centos1
- Boot media: Network installation
- Centos Full Network Install URL:
- VM Image Pathname: /var/lib/libvirt/images/centos1.qcow2
- Memory: 2048MB
- Disk space: 15GB
- CPUs: 1
- Perform the following steps:
- Launch the KVM virtual machine manager by clicking Applications -> System Tools -> Virtual Machine Manager.
- When prompted, enter your root password.
- Click the create a new VM icon located near the top left-corner of the application window.
- Select the Network Install option and click Forward.
- Enter (copy and paste) the URL located at the top of this section (depending whether you are at Seneca College or not) and click Forward.
- Set RAM size to 2048 MB and click Forward.
- Set Hard Disk size to 15GB and click Forward.
- Enter the name: centos1, select the option: Customize configuration before install, and click Finish.
- During the install, select Gnome Desktop software selection). For partitioning, select I will configure partition settings, click done, then select Click here to create them automatically. Set the / partition for ext4 file-system type, and click Done.
- Click on Network and Hostname. The network should be turned on. For hostname, enter: centos1 and then click Done.
- Complete the installation. Login to your regular user account, and perform a yum update for the centos2 VM (reboot if required). Make certain to adjust your screen-saver settings if desired.
- Repeat the steps as you did in the previous investigation (Investigation1 Part 1) to stop and disable firewalld, install iptables-services, start and enable iptables for this newly-created VM.
- Repeat the steps as you did with c7host post-install to disable SELinux and perform a yum update.
- Issue the following command to obtain the IPADDR for your centos1 VM to record in your lab2 logbook:
ifconfig eth0
- Record the time taken to install, and compare this to the time taken by the previous installations in your lab2 logbook.
Part 2: Installing from a Network (Minimal Install - CLI)
- VM Details:
- VM Name (and hostname): centos2
- Boot media: Network installation
- Centos Full Network Install URL:
- VM Image Pathname: /var/lib/libvirt/images/centos2.qcow2
- Memory: 2048MB
- Disk space: 20GB
- CPUs: 1
- Perform the following steps:
- Create the VM (called centos2) as you did with the centos1 machine, except for the following difference
When customizing your partitions, do the same operation that you did in centos2 (with Minimal Install software selection), but after automatically creating the partitions, reduce the size of the root LVM partition to 8000 MB and add an LVM partition with a size of 2000 MB (mount point: /home, name: home, and make certain root and /home partitions have ext4 file system). - Complete the installation. Login to your regular user account, and perform a yum update for the centos2 VM (reboot if required). Make certain to adjust your screen-saver settings if desired.
- Repeat the steps as you did in the previous investigation (Investigation 1 Part 1) to stop and disable firewalld, install iptables-services, start and enable iptables for this newly-created VM.
- Repeat the steps as you did with c7host post-install to disable SELinux and perform a yum update.
- The ifconfig command is not available in centos2. Issue the following command to obtain and record your centos2 IPADDR in your lab2 logbook:
ip address
- Record the time taken to install, and compare this to the time taken by the previous installations in your lab2 logbook.
Part 3: Installing from a Network using a Kickstart File
- VM Details:
- VM Name (and hostname): centos3
- Boot media: Network installation
- Centos7 Full Install Network URL:
- Kickstart File URL: http://matrix.senecac.on.ca/~andrew.smith/ops235/centos7-kickstart-v01.cfg
- VM Image Pathname: /var/lib/libvirt/images/centos3.qcow2
- Memory: 2048MB
- Disk space: 15GB
- CPUs: 1
- Perform the following steps:
- During the install, select the network URL, but click options for the network install and enter (copy and paste) the kickstart URL displayed above).
- Observe the installation. How is it different from booting from a downloaded image?
- Record the time taken to install, and compare this to the time taken by the previous installations.
If the during the installation, you see the message at the bottom Pane is Dead, click the Virtual Machine menu at the top, select Shut Down -> Force Off, right-click on centos3 in the virtual manager window and select Delete. Redo the VM setup for a new instance of the centos3 VM. - What happens when the installation is finished?
- Click the kickstart file link in a web-browser, and record the following information to access your centos3 VM:
- Regular-user account name
- Regular-user account password
- Root Password
- Boot the virtual machine and log in (use the user ID and password information from the previous step to gain access to this VM).
- Compare the experience to the first time you booted the other virtual machines.
- Repeat the steps as you did in the previous investigation (Investigation1 Part 2) to stop and disable firewalld, install iptables-services, start and enable iptables for this newly-created VM.
- Repeat the steps as you did with c7host post-install to disable SELinux and perform a yum update.
- Issue the following command to obtain the IPADDR for your centos1 VM to record in your lab2 logbook:
ifconfig eth0
- Remember that centos3 is text-based interface only (no graphics). To recover from a blank screen, press a key (like the SPACE key) to return to the screen display.
- Record the time taken to install, and compare this to the time taken by the previous installations in your lab2 logbook.
Answer the INVESTIGATION 2 observations / questions in your lab log book.
INVESTIGATION 2: MANAGING VIRTUAL MACHINES (KVM)
Part 1: Backing Up Virtual Machines
- Perform the following steps:
- Shut down your centos1, centos2, and centos3 VMs. For centos2 and centos3, which are CLI-only, you can issue the following command as root to shutdown:
shutdown -h
. Please be patient, the VMs will shut down! - In your c7host VM, change to the images directory by issuing the command:
cd /var/lib/libvirt/images/
Note the size of the files in this directory. What do these files contain? - Make a compressed backup of your centos1.qcow2 centos2.qcow2, and centos3.qcow2 files to your regular user's home directory by issuing each command (one at a time):
gzip < centos1.qcow2 > ~YourRegularUsername/centos1.qcow2.backup.gz
gzip < centos2.qcow2 > ~YourRegularUsername/centos2.qcow2.backup.gz
gzip < centos3.qcow2 > ~YourRegularUsername/centos3.qcow2.backup.gz
(NOTE: Make certain to use the redirection signs "<" and ">" properly in the command!) - Compare the size of the compressed and original files (hint: use ls -lh). If file is very large (like 15GB), you didn't compress it and you need to remove that file and perform the previous step until you get it right!
- Start the centos3 VM.
- Make certain that you are in your VM and not in your main system!
- Wreck only your centos3 system! Try this command inside the centos3 virtual machine:
rm -rf /*
(ignore error messages). - Shut down the centos3 VM. If you tried to start the centos3 VM, it would not boot since all system files have been removed!
- Restore the original image from the backup in your home directory by typing this command:
gunzip < ~YourUserId/centos3.qcow2.backup.gz > centos3.qcow2
- Restart the VM. Is it working normally?
- Create compressed backups of your other virtual machines (ie. centos1 and centos2).
- You should make a copy of the xml configuration file in case you "wipe" and re-install the host machine, and want to add a restored VM backups to the virtual machine manager list. We will demonstrate using the centos3 xml configuration file, and prove that a "clone" can be added to your list.Please perform the following step:
- Execute the following command:
virsh dumpxml centos3 > centos3.xml
- Examine the file
centos3.xml
. What does it contain? What format is it in? - We will now learn how to download a compressed image file and xml configuration file and add it as a VM to the virtual manager menu.
- Issue the following commands:
- The downloaded file "practical1.img.gz" is a "raw image compressed VM file", but will work the same for a Virtual Machine as the qcow2 file format.Copy these files to the /var/lib/libvirt/images directory and decompress that raw image file.
- Make certain your present working directory is: /var/lib/libvirt/images
- Issue the command:
virsh define practical1.xml
- What happened in the virtual manager window? To remove a VM entry in the Virtual Manager window, simply issue the command: virsh undefine vm_name (without the .xml file extension)
- Launch the VM to see if it boots-up
- Can you log into this VM? Perhaps your instructor will give you a clue in week #7... >;p
- For the remainder of these labs, it is assumed that you will backup both the images and xml configuration files for all Virtual machines, when asked to backup your virtual machines. It is also highly recommended to backup these files to an external storage device (eg. USB key) in case the host machine gets "wiped" and you need to rebuild your HOST machine and then restore your Virtual Machines...
- Answer this question in your log book:
- In order to fully back up a virtual machine, what information should be saved in addition to the virtual machine image?
Part 2: Using Shell Scripts for VM Backup & Management
You will continue our use of Bash Shell scripting by first creating a Bash Shell script that will allow the Linux sysadmin to select their created VMs for backup to root's home directory. Afterwards you will download, view and run a couple Bash Shell scripts that use the virsh command to start and stop your virtual machines.
- Perform the following steps:
- Start the centos1 virtual machine, and stop the centos2 and centos3 virtual machines.
- Switch to the c7host machine, and open a shell terminal.
- Enter these admin commands into your c7host machine and note the result:
-
virsh list
-
virsh list --all
-
virsh list --inactive
-
- Now, shut-down your centos1 VM normally, and close the centos1 VM window.
- Switch to your terminal and issue the command:
virsh start centos1
- Using the appropriate command check to see if your centos1 VM is now running.
- There are other commands that can be used (such as suspend, or shutdown). The "shutdown" command may not always work since it relies on the guest handling a particular ACPI event. Why do you think it is useful to have commands to manipulate VMs?
- Since this is a text-based version of Linux, you do not need to turn off the screen-saver.
- Open a Bash shell terminal and login as root.
- Use a text editor (such as
vi
ornano
) to create a Bash Shell script called:backupVM.bash
in /root's home directory. - Enter the following text content into your text-editing session:
#!/bin/bash
# backupVM.bash
# Purpose: Creates system info report
#
# USAGE: ./report.bash
#
# Author: *** INSERT YOUR NAME ***
# Date: *** CURRENT DATE ***
if [ $PWD != "/root" ] # only runs if in root's directory
then
echo "You must be located in /root" >&2
exit 1
fi
- Save your editing session, but remain in the text editor.
- This shell script is designed particularly for your centos1, centos2, and centos3 VMS.
- The code displayed below will prompt the user if they wish for all VMs to be backed-up; otherwise, allow the user the option of specifying which VMs to be backed-up. Add the following code
read -p "Backup all VMs? (y|n):" answer # prompt if all VMs to be backed-up
if [ "$answer" = "y" ] # Backup all VMs if answer is yes
then
for num in 1 2 3 # Determinant loop for 3 arguments: 1, 2, and 3
do
echo "Backing up VM #$num"
gzip < /var/lib/libvirt/images/centos$num.qcow2 > /root/centos$num.qcow2.backup.gz
echo "VM #$num BACKUP DONE"
done
elif [ "$answer" = "n" ]
then
read -p "Which VM should be backed up? (1/2/3): " numanswer
until echo $numanswer | grep "^[123]$" >> /dev/null # Look for match of single digit: 1,2, or 3
do
read -p "Invalid Selection. Select 1, 2, or 3: " numanswer
done
echo "Backing up VM #$numanswer"
gzip < /var/lib/libvirt/images/centos$numanswer.qcow2 > /root/centos$numanswer.qcow2.backup.gz
echo "VM #$numanswer BACKUP DONE":
else
echo "Invalid Selection... Aborting program"
exit 2
fi
- Save, set permissions, and then run that shell script to backup centos1. Confirm that this script did backup this image to root's home directory
- Use the
wget
command to download, study, and run the following shell scripts on-line:https://scs.senecac.on.ca/~murray.saul/vm-start-text.bash
https://scs.senecac.on.ca/~murray.saul/vm-stop-text.bashhttps://scs.senecac.on.ca/~murray.saul/vm-start.bash
https://scs.senecac.on.ca/~murray.saul/vm-stop.bash - Try to understand what these Bash Shell scripts do.
- You have completed lab2. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".
Answer INVESTIGATION 2 observations / questions in your lab log book.
LAB 2 SIGN-OFF (SHOW INSTRUCTOR)
- Perform the Following Steps:
- Use the virsh start command to launch all the VMs (centos1, centos2, and centos3).
- Switch to your c7host VM, open a terminal, login as root, and change directory to /root/bin.
- Issue the Linux command:
wget http://matrix.senecac.on.ca/~murray.saul/ops235/lab2-check.bash
- Give the lab2-check.bash file execute permissions (for the file owner).
- Run the shell script and if any warnings, make fixes and re-run shell script until you receive "congratulations" message.
- Arrange proof of the following on the screen:
- ✓ All VMs:
- All 4 VMs created and running
- Proof of yum updates on ALL VMs (i.e. results from yum update command)
- ✓centos2 VM:
- Run the lab2-check.bash script in front of your instructor (must have all
OK
messages)
- Run the lab2-check.bash script in front of your instructor (must have all
- ✓ Lab2 logbook notes completed.
- ✓ All VMs:
Practice For Quizzes, Tests, Midterm & Final Exam
- What is the name of the CentOS installation program?
- What is the name of the file created by the CentOS installation program?
- Which type of installation works best for confirming compatibility with hardware before installation? Why?
- Which type of installation works best for installing large numbers of computers? Why?
- How can you reduce the number of software updates required immediately after installation?
- How do you start and stop virtual machines?
- How do you SSH into your virtual machines?
- List the steps to install a VM from:
- Downloaded iso file
- Network install (without kickstart file)
- Network install (with kickstart file)
- What is the purpose of the virsh command?
- How to start and stop VMs using the virsh command?
- List the steps to correctly backup your VMs to a USB disk
- List the steps to correctly restore your VMs from a USB disk to your c7host VM.
- How can you prompt the user for data and store into a variable?
- How do you perform mathematical operations in the Bash shell and within a Bash shell script?
- What is the difference between a determinant loop and an in-determinant loop?
- Show a few examples how loops can be used to error-check when prompting the user for data.
- What is the purpose of the && and || symbols when used with logic?