OPS235 Lab 2 - CentOS7 - SSD

LAB PREPARATION

At the end of lab2, your VMware Workstation application will contain 4 virtual machines. You will now have the option to run one virtual machine at a time, or run all machines simultaneously to learn about networking (covered in later labs)

Purpose / Objectives of Lab2

In this lab, you will create another three virtual machines to learn how to install Centos Linux in different ways including network installs.

Main Objectives

• Installing Virtualization Software on your c7host machine
• Create 3 separate VMs (virtual machines) using different installation methods:

• Centos Live DVD (with Install to Harddisk program)
• Network Centos Installation without configuration file
• Network Centos Installation with configuration file (Kickstart)

• Understand the advantages and disadvantages of each type of installation, and be able to select the best installation method for a particular situation.
• Manipulate virtual machines by CLI (virsh)
• Properly backup VMs and VM configuration in virtual manager application onto home directory and to external source (USB Key)

• Create and run Bash Shell scripts to automatically create a post-install report for an installed VM.

Minimum Required Materials			Linux Command Reference
Solid State Drive	<b>USB key (for backups)	Lab2 Log Book	Virtualization virt-manager virsh Installation Guides Installing & Using KVM on CentOS Using KVM (tutorial) virsh command reference	Miscellaneous gzip, gunzip grep wc pwd ls more file wget chmod vi	Matrix Online Tutorials: Shell Scripting - Part 2 (Logic & Math Expressions): /home/murray.saul/scripting-2 Shell Scripting - Part 3 (Loops) /home/murray.saul/scripting-3

INVESTIGATION 1: USING VIRTUALIZATION SOFTWARE TO CREATE VIRTUAL MACHINES

Part 1: Virtualization Application Setup / Comparison Chart

comparison chart in lab2 logbook.

Record VM Installation in Lab2 (Installation Comparison Chart):

You will be learning to perform several different type of CENTOS Linux installs. Lab2 already has an empty table for comparing various Linux installs. You were required in lab1 to record your observation for your c7host installation.

As you proceed throughout this lab, you will be required to fill in the comparison chart for three of the VMs (virtual machines) that you will be installing.

Complete the following steps to install and run the virtual manager application:

1. Launch the VMware application.
2. Select Open Virtual Machine, and select the VM called c7host on your Solid State Drive.
3. Launch your c7host machine, and login as as a regular user.
4. Open a shell terminal.
   
   WARNING: You must perform a yum update on your c7host machine before proceeding with the next steps. You issue the following command to update your software for this machine:
   yum update
   
   
5. You will need to download an image file for the Centos7 LIVE DVD by issuing the following command (best works while at Seneca):
   wget http://belmont.senecac.on.ca/centos/7/isos/x86_64/CentOS-7-x86_64-LiveGNOME-1511.iso
   
   
6. 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 Host Machine
You must restart your c7host machine after installing the virtualization program above. If you fail to do this, you may experience virtualization network problems!

This will install many applications (including):

• kvm/qemu - the hypervisor and other hardware emulation systems.
• A system service named libvirtd that manages the VMs.
• A graphical tool for managing virtual machines (virt-manager) and the virsh command-line tool.
  
  

7. Start the virtualization service: service libvirtd start
   

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.

8. To Disable firewalld issue the following commands:
   systemctl disable firewalld
systemctl stop firewalld
   
   
   
9. To install and enable the IPTables services, issue the following commands:
   yum install iptables-services
systemctl enable iptables
systemctl start iptables
   
   

Run virt-manager as a regular user, not as root Otherwise all your virtual machines will be owned by root and you won't be able to use them as a regular user.

9. Start the graphical tool by selecting the menu options Applications>System Tools>Virtual Machine Manager or by typing the command virt-manager
   
   
10. You will be learning to perform several different type of CENTOS Linux installs. Lab2 has a comparison chart for comparing various Linux installs. You were required in lab1 to record your observation for your centos1 installation.
    
    
11. As you proceed throughout this lab, you will be required to fill in the comparison chart for the remaining 3 virtual machines that you will be installing.

Part 2: Installing from a Downloaded Image (Centos7 LIVE CD)

Perform Downloads and Network installs at Seneca It is recommended to perform this lab in one of Seneca College's labs. This lab uses servers which are on the Seneca network and which are not available from other locations (such as your home). If you attempt this lab from another location, adjust the belmont.senecac.on.ca URLs to point to another mirror server -- note that you may need to change the directory name as well as the server name. The installation of the centos3 virtual machine must be done at Seneca.

VM Details:

VM Name (and hostname): centos1

Boot media: LIVE CD Image (downloaded iso file)

Installation source: Downloaded Centos7 LIVE CD image (http://belmont.senecac.on.ca/centos/7/isos/x86_64/CentOS-7-x86_64-LiveGNOME-1511.iso)

VM Image Pathname: /var/lib/libvirt/images/centos1.img

Memory: 2GB

Disk space: 10GB

File System (root partition): ext4

CPUs: 1

You do not need to burn a DVD for the Centos7 install image. You can simply download an image file (.iso), and refer to this downloaded image in order to install the Linux OS. This is the second method of installation that we will now investigate.

1. Open a web-browser, click on the link below to save on your Windows machine in your Seneca Lab (Downloads section).
   
   http://belmont.senecac.on.ca/centos/7/isos/x86_64/CentOS-7-x86_64-LiveGNOME-1511.iso
   
   
2. Launch the VMWare Workstation application.
3. Click on the icon to Create a New Virtual Machine and select Custom (Advanced).

When your centos1 LIVE machine boots-up, immediately double-click on the Install to Hard Disk icon to run the installation program.

4. The virtual machine will now start.
5. Immediately double-click on the icon called Install to Hard Disk.
6. Start timing your installation and making notes for centos1 virtual machine in the installation comparison chart in lab2 logbook.
7. Select your downloaded iso Centos7 Gnome LIVE image (under Downloads folder) and click Next. Basically, you perform the same steps is in lab1 (i.e. select Custom (Advanced) with 2 GB of RAM, the VM name will be called centos1 and the Hard Disk size will be 10 GB (not 20GB).
8. When your VM boots-up, Double-click Install to Hard Drive. The installation program, similar to the one used when installing CentOS in Lab 1, will appear. You basically perform the same installation operations for this VM including for Date & Time, Network & Hostname, and Installation Destination. Make certain to use the hostname: centos1 as opposed to c7host) for this installation. (with a few slight differences).
9. For Installation Destination, select the destination option: I will configure partitioning and then click Done. Make certain that the Partition Scheme is set to LVM and then click on the link: Click to Create Automatically. Done. Check to make certain that the root partition has file system type: ext4.
10. Accept the changes and then click Begin Installation.
    1. You will be required to make selections very similar to what you did in lab1.
    2. While the system is installing, take a few minutes to record your observations (including slight differences with centos1 install as opposed to c7host install).
    3. When the installation process is complete, note the time required to install this system and record in the installation comparison chart of your lab2 logbook.
       
       
11. Power-off your Centos7 LIVE system.
12. Restart your centos1 VM, and enter 1, 2, c, c, like you did in lab1.
13. Finish the final steps in the setup process (like you did in lab1).
14. It is recommended that you turn off the screen-saver (like you did in Lab1: Turn-off Screen Saver Lock).

Important Network Service Tasks Please perform the tasks below in order allow these CentOS systems to be able to communicate with each other. Failure to properly perform these operations can cause problems in future labs.

20. Make certain to disable SELinux for centos1 (refer to lab1)
21. Start and enable the SSH server to allow access to your virtual machine with these commands (semi-colon allows commands to be run in sequence):
    systemctl start sshd; systemctl enable sshd
22. Find out the IP address of your virtual machine and the name of your Ethernet network adaptor: ifconfig
23. Enter the following command on your virtual machine to create a firewall exception to allow ssh traffic into the machine:
    iptables -I INPUT -p tcp -s0/0 -d0/0 --dport 22 -j ACCEPT
24. If you are logged in as root, logout to your regular user account.
25. Confirm that you can ssh to your virtual machine from the host (your main CentOS installation): ssh regularuserid@IPaddress (where regularuserid is your regular user login id, and IPaddress is the IP_ADDRESS of your centos1 VM!).

Remember to Backup your VM to USB Key!
Remember that you need to backup your centos1 VM to your USB key before you leave your Seneca lab, or you will lose your work!

Part 2: Installing from a Network

Authenticate to the network The rest of this lab uses network access. Be sure to authenticate to the network using your browser before proceeding.

VM Details:

VM Name (and hostname): centos2

Boot media: Network installation

Installation source URL: http://belmont.senecac.on.ca/centos/7/os/x86_64/

VM Image Pathname: /var/lib/libvirt/images/centos2.img

Memory: 2048MB

Disk space: 20GB

CPUs: 1

1. Create the VM (called centos2) as you did with the centos1 machine, except for the following differences:
   
   
   1. Select Network Installation using the installation source URL displayed above.
   2. When customizing your partitions, do the same operation that you did in centos2, 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).
   3. Don't forget to install the GNOME desktop here as you will need a GUI for Centos2
      
      
2. 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.
3. Repeat the steps as you did to start the SSH service, set iptables to accept connections via ssh, test connections between centos2 and centos1, and disable SELinux (refer to lab1).
4. Record the time taken to install, and compare this to the time taken by the previous installations. Record your findings in the Installation Comparison chart in lab2 logbook.

Remember to Backup your VM to USB Key!
Remember that you need to backup your centos2 VM to your USB key before you leave your Seneca lab, or you will lose your work!

Part 3: Installing from a Network using a Kickstart File

VM Details:

VM Name (and hostname): centos3

Boot media: Network installation

Installation source URL: http://belmont.senecac.on.ca/centos/7/os/x86_64/

Kickstart File URL: http://matrix.senecac.on.ca/~andrew.smith/ops235/centos7-kickstart-v01.cfg

VM Image Pathname: /var/lib/libvirt/images/centos3.img

Memory: 2048MB

Disk space: 15GB

CPUs: 1

1. Create the VM as you did with the centos2 virtual machine, specifying a network install as before, but specify the kickstart location under the "options section" for network install. What do you think is the purpose of this kickstart file?
2. Observe the installation. How is it different from booting from a downloaded image?
3. Complete the installation. 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.
4. What happens when the installation is finished?
5. Take a look at the kickstart file (eg. view url in a webj-browser) to determine the root password as well as the name and password for the first user account!
6. Boot the virtual machine and log in (use the user ID and password information from the previous step). Compare the experience to the first time you booted the other virtual machines. Record this information in the table contained in Investigation 4.
7. Repeat the steps as you did to start the SSH service, set iptables to accept connections via ssh, test connections between centos3 and centos1, and disable SELinux (refer to lab1).
8. 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.
9. Record the time taken to install, and compare this to the time taken by the previous installations. Record your findings in the Installation Comparison chart in lab2 logbook.

Answer the Investigation 1 observations / questions in your lab log book.

Remember to Backup your VM to USB Key!
Remember that you need to backup your centos2 VM to your USB key before you leave your Seneca lab, or you will lose your work!

INVESTIGATION 2: COMMON POST-INSTALL TASKS

Part 1: Perform Software Updates

Allow Time to Perform Yum Updates Allow sufficient time in order to perform updates prior to the end of the lab. Since you will be updating ALL of your VMs, allow 15-20 "lead-time" to start your updates and to backup your VMs prior to the end of the lab. NEVER force a shut-down of your VM while updates are running, since this will ruin your VM, and you will have to restore from a backup, or redo your labs for that VM!

It is important as a Linux System Administrator to update software on your Linux system periodically. Performing periodic updates will fix software bugs and inefficiencies as well as apply security patches in order to better secure your Linux server.

You are required to perform the following command for ALL of your 4 VMs:

yum update

This will download and install all of the packages that have been updated since the installation DVD image was created. If you complete this command at Seneca, it should run quite fast as Seneca College hosts a CentOS Repository mirror (a copy of all of the current CentOS packages, on a local web server). You will be reminded at the end of each of the remaining labs to perform software updates on ALL of your VMs.

Part 2: Managing Virtual Machines from the Command Line

Manage virtual machines from the host The commands used to manage virtual machines must be executed on the host (your disk pack) and not inside a virtual machine.

1. Start the centos1 virtual machine, and stop the centos2 and centos3 virtual machines.
2. Switch to the c7host machine, and open a shell terminal.
3. Enter these admin commands into your c7host machine and note the result:

virsh list

virsh list --all

virsh list --inactive

Virtual Machine Does not Shutdown from Command If the Virtual machine fails to shutdown from the virsh shutdown command, then you can go to the Virtual Machine manager and halt or shutdown within the VM itself, then you can click the PowerOff button in the VM window. You'll want to avoid a forced shutdown since those are equivalent to yanking the power cord out of the wall on a physical machine!

4. Now, shut-down your centos1 VM normally, and close the centos1 VM window.
5. Switch to your terminal and issue the command: virsh start centos1
6. Using the appropriate command check to see if your centos1 VM is now running.
7. 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?
8. Since this is a text-based version of Linux, you do not need to turn off the screen-saver.

Part 3: Backing Up Virtual Machines

Backing up VMs There are two general processes in order to back up your images: Compressing your images (also recommended to backup up to external storage USB Key) using the gzip command. Backup the VM xml configuration file (preferably to USB key) using virsh shell command to add VM to virtual machine manager list (in the event that the HOST machine is "wiped" and re-installed, but VM images and xml configuration files have been backed up external storage). Taking the time to backup the image of the Operating System's file system allows the user to return to a "restoration point" using the gunzip command in case something bad occurs to the OS during a lab. Failure to take the time to make and confirm backups can result in loss of lab work for the student!

1. Shut down all of the virtual machines.
2. Change to the directory /var/lib/libvirt/images/. Note the size of the files in this directory. What do these files contain?
3. Make a compressed backup of the centos3.img file to your home directory with this command: gzip < centos3.img > ~YourUserId/centos3.img.backup.gz
   (Note: Make certain to use the redirection signs "<" and ">" properly in the command!)
4. 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!
5. Start the centos3 VM.
6. Make certain that you are in your VM and not in your main system!
7. Wreck only your centos3 system! Try this command inside the centos3 virtual machine:rm -rf /* (ignore error messages).
8. Shut down the centos3 VM. If you tried to start the centos3 VM, it would not boot since all system files have been removed!
9. Restore the original image from the backup in your home directory by typing this command: gunzip < ~YourUserId/centos3.img.backup.gz > centos3.img
10. Restart the VM. Is it working normally?
11. Create compressed backups of your other virtual machines (ie. centos1 and centos2).
12. 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:
13. Execute the following command: virsh dumpxml centos3 > centos3.xml
14. Examine the file centos3.xml. What does it contain? What format is it in?
    
    
15. 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.
16. Issue the following commands:
    • wget http://cs.senecac.on.ca/~murray.saul/ops235/practical1.img.gz
    • wget https://scs.senecac.on.ca/~murray.saul/ops235/practical1.xml
      
      

17. Copy these files to the /var/lib/libvirt/images directory and decompress the image
18. Make certain your present working directory is: /var/lib/libvirt/images
19. Issue the command: virsh define practical1.xml
20. 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)
21. Launch the VM to see if it boots-up
22. Can you log into this VM? Perhaps your instructor will give you a clue in week #7... >;p
    
    

Shutting Down the Host while Virtual Machines are Running If you shut down your host system while virtual machines are running, they will be suspended, and will resume the next time you boot your host system.

22. 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...
23. 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?

24. A previous OPS235 student graciously created a shell script that you can download and run to check to see how you performed this lab (to see if you are on the right track).
    Simply issue the command: wget http://matrix.senecac.on.ca/~murray.saul/ops235/lab2check2.bash and run on your c7host machine.
    
    If the shell script indicates any major errors, please inform your OPS235 instructor or lab assistant to advise what to do.
    
    

Part 4: Automating Routine Tasks (Shell Scripting)

Bash Shell Scripting Tips: Data Input: A shell script can obtain data from a number of methods: reading input files, using arguments when issuing command (positional parameters), or prompting for data to store in a variable. The later method can be accomplished by using the read command, for example: read -p "Enter your name: " userName. Mathematical Expressions: In shell scripting, data is stored in variable as text, not other data types (ints, floats, chars, etc) like in compiled programs like C or Java. In order to have a shell script perform mathematical operations, number or variable need to be surrounded by two sets of parenthesis ((..)) in order to convert a number stored as text to a binary number. Examples var1=5;var2=10 echo "$var1 + $var2 = $((var1+var2))" Note: shell does not perform floating point calculations (like 5/10). Instead, other commands like awk or bc would be required for floating point calculations (decimals) Loops (iteration): Loops and logic are a very important elements of shell scripting (not to mention programming as well). Determinant loops (such as for loops) usually repeat for a preset number of times (eg. counts, positional parameters stored). In-determinant loops (such as while or until loops) may repeat based on unknown conditions (like waiting for user to enter correct data). Test conditions can be used with in-determinant loops, or even commands! If a command runs successfully (eg ls, cd, grep matching a pattern), zero (true) value is returned, otherwise a non-zero (false) value is returned. Command options or redirection to /dev/null can be used to just test if command runs, but not display stdout or stderr. Conditional statements "and" (&&) / "or" (||) can also be used when testing multiple conditions. Examples (try in a shell script) set ops235 is fun for x do  echo "argument is $x" done for x in $(ls) do  echo "Filename: $x" done read -p "enter a whole number: " num until echo $num | grep -q "^[0-9][0-9]*$" do  read -p "Incorrect. Please enter WHOLE NUMBER: " num done read -p "pick a number between 1 and 10: " num while [ $num -lt 1 ] || [ $num -gt 10 ] do  read -p "Incorrect. Please pick number between 1 and 10: " num done

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.

If you require additional practice in creating shell scripts using logic, loops and mathematical operations, run the commands in your Matrix account:

• /home/murray.saul/scripting-2
• /home/murray.saul/scripting-3

Perform the following steps in your c7host machine:

1. Open a Bash shell terminal and login as root.
2. Use a text editor (such as vi or nano) to create a Bash Shell script called: backupVM.bash in /root's home directory.
3. 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

4. Save your editing session, but remain in the text editor.
5. This shell script is designed particularly for your centos1, centos2, and centos3 VMS.
6. 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$num.img > /root/centos$num.img.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.img > /root/centos$numanswer.img.backup.gz

 echo "VM #$numanswer BACKUP DONE":
else
 echo "Invalid Selection... Aborting program"
 exit 2
fi

7. 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
8. 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.bash
https://scs.senecac.on.ca/~murray.saul/vm-start.bash
https://scs.senecac.on.ca/~murray.saul/vm-stop.bash

9. Try to understand what these Bash Shell scripts do.
10. You have completed lab2. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".

Answer all observations / questions in your lab log book.

LAB 2 SIGN-OFF (SHOW INSTRUCTOR)

Backup ALL of your VMs!
If you have successfully completed this lab, make a new backup of all of your virtual machines onto your UBS Key.

Download and Run Lab2 Checking Script & Show Lab2 Work

Perform the Following Steps:

1. Make certain ALL of your VMs are running.
2. Switch to your centos2 VM, open a terminal, login as root, and change directory to /root/bin.
3. Issue the Linux command: wget http://matrix.senecac.on.ca/~murray.saul/ops235/lab2-check-vm.bash
4. Give the lab2-check.bash file execute permissions (for the file owner).
5. Run the shell script and if any warnings, make fixes and re-run shell script until you receive "congratulations" message.
6. Arrange proof of the following on the screen:

✓ All VMs:

• All 4 VMs created and running
• Disk layout and size correct on ALL virtual machines
• Proof of yum updates on ALL VMs

✓centos2 VM:

• Creation of your bash shell script called myreport.bash
• A list of your iptables rules (command: iptables -L)
• Output from running the lab2-check.bash script with all OK messages

✓ Lab2 logbook notes and Installation Comparison chart completed.

Practice For Quizzes, Tests, Midterm & Final Exam

1. What is the name of the CentOS installation program?
2. What is the name of the file created by the CentOS installation program?
3. Which type of installation works best for confirming compatibility with hardware before installation? Why?
4. Which type of installation works best for installing large numbers of computers? Why?
5. How can you reduce the number of software updates required immediately after installation?
6. How do you start and stop virtual machines?
7. How do you SSH into your virtual machines?
8. List 2 ways that you can access your root account
9. What is the difference between the commands su and su -  ?
10. What is the home directory for the user "root"?
11. How do you determine the host name of your GNU/Linux workstation?
12. What command can display the NIC's MAC address?
13. What command is used to get a list of running processes on your newly-installed system?
14. How create in a shell script to force the user to run shell script as root?
15. How to store each file-name in your current directory as separate positional parameters? How to list all of the positional parameters? How to display the number of positional parameters?