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OPS245 Lab 2

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{{Admon/caution|DO NOT USE THIS VERSION OF THE COURSE. This page will no longer be updated.|'''Debian version here:''' https://seneca-ictoer.github.io/OPS245

'''CentOS version here:''' https://seneca-ictoer.github.io/OPS245-C7 '''Andrew's version here:''' http://wiki.littlesvr.ca/wiki/OPS245_Lab_2}}

= LAB PREPARATION =

[[Image:vmware-1a.png|thumb|right|400px|At the end of lab2, your VMware Workstation application will contain '''4 virtual machines''' ('''c7host''' in your '''VMware Workstation''' application, and '''centos1, centos2, centos3 VMs''' in your '''KVM''' application). 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) ]]

# Enter the name: '''centos1''', AND then select the option: '''Customize configuration before install''', and click '''Finish'''.

# Another dialog will appear. Click '''CPUs''' (or "processors") and on right-side under Configuration select '''Copy Host CPU Configuration''', click '''Apply''', and then click '''Begin Installation''' at the top left-hand side.

#During the install, select '''Gnome Desktop''' (software selection). For partitioning, select '''I will configure ~~partition settings~~partitions'''settings, click done, then select '''Click here to create them automatically'''. Set the / partition for '''ext4''' file-system type, and click '''Done'''.

#Set the correct '''Date and Time Zone''', and then click on '''Network and Hostname'''. The network should be turned '''ON'''. For hostname, enter: '''centos1''' and then click '''Done'''.

# Make sure that when you create your regular user account you check the box to make them an administrator.

#When selecting the install options for centos2, do the same operation that you did in centos1 (but with '''Minimal Install''' software selection instead), but after '''automatically creating the partitions''', reduce the size of the root logical volume to '''8 GiB''' and add a logical volume with a size of '''2 GiB''' (mount point: '''/home''', name: '''home''', and make certain root and /home logical volumes have '''ext4''' file system).

# Complete the installation. Login to your regular user account.

# Repeat the steps as you did in the previous investigation ([https://wiki.cdot.senecacollege.ca/wiki/~~OPS235_Lab_2~~OPS245_Lab_2#Part_1:_Install_KVM_Virtualization_Application 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 '''turn off (permissive) SELinux''' (using the command 'vi' instead of 'vim') and perform a '''yum update'''.

# Issue the following command to obtain and record your centos2 IPADDR in your lab2 logbook: <code>ip address show</code>

{| width="40%" align="right" cellpadding="10"

|- valign="top"

|colspan="2"|{{Admon/important|Using a Kickstart file with a local install|Under most circumstances, a network install would be drawing the installation data from a server in the local network, allowing it to transmit data at higher speeds than we can achieve over the internet. If your download speed is slow enough that network installs are failing, it is acceptable to install these VMs from local media. However, you will still need to provide a kickstart file to Centos3. To do so, start the install process as normal for an installation from an iso file, but when presented with the menu giving you the option to 'Install CentOS 7' or 'Test this media & install CentOS 7', ~~highlite~~ highlight 'Install CentOS7' and press '''<tab>'''. This will open a prompt at the bottom of the window for you to enter grub configuration options. Type '''inst.ks=https://~~ict~~raw.~~senecacollege~~githubusercontent.cacom/~~~ops245~~OPS245/labs/main/centos7-kickstart~~-local~~.cfg''' ~~andf~~ and hit '''<enter>'''.}}

|}

:::*Home: http://mirror.netflash.net/centos/7/os/x86_64/

:: '''Kickstart File URL (Kernel options): '''

:::* Home:''' ks=https://~~ict~~raw.~~senecacollege~~githubusercontent.cacom/~~~ops245~~OPS245/labs/main/centos7-kickstart.cfg

:: '''VM Image Pathname:''' /var/lib/libvirt/images/centos3.qcow2

:: '''Memory:''' 2048MB ('''IMPORTANT''' Do not use less than 2048MB during installation.)

# Create the VM (called '''centos3''')

# During the install, copy the network URL, then click the '''URL options''' to expand the '''kernel options''' input textbox. Type the following in the kernel options textbox: <ul><li>ks=https://~~ict~~raw.~~senecacollege~~githubusercontent.cacom/~~~ops245~~OPS245/labs/main/centos7-kickstart.cfg</li></ul>

# Then click the '''forward''' button to proceed. Make certain to select the correct Memory Size and Disk Space size shown in the VM Details above

# Make certain to enter the name: '''centos3''', AND then select the option: '''Customize configuration before install''', and select '''Copy Host CPU Configuration''', click '''Apply''', and then click '''Begin Installation'''.

# In your '''c7host''' VM, open a new Terminal window.

# Use elevated privileges to list the size and names of files in<code>/var/lib/libvirt/images/</code><ul><li>What do these files contain?</li></ul>

# Use the command <code>sudo -i</code> and enter your password if prompted. You are now root until you use the command ~~<code>~~'''exit~~</code>~~ ''' to return to your normal user account.

# Change to the images directory by issuing the following command: <code> cd /var/lib/libvirt/images/</code>. Note that you did not need to use sudo, as you are already using elevated permissions.

# 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 (create '''backups''' directory '''within your regular user's home directory''' before running these commands): <code>gzip < centos1.qcow2 > ~YourRegularUsername/backups/centos1.qcow2.gz</code> <code>gzip < centos2.qcow2 > ~YourRegularUsername/backups/centos2.qcow2.gz</code> <code>gzip < centos3.qcow2 > ~YourRegularUsername/backups/centos3.qcow2.gz</code><ul>'''NOTE:''' Make certain to use the redirection signs "<" and ">" properly in the command!</ul>

# We will now learn how to download a compressed image file and XML configuration file and add it as a VM to the Virtual Machine Manager menu.

# Issue the following commands:<ul><li><code>wget https://~~ict~~matrix.senecacollege.ca/~ops245/centos4.qcow2~~.backup~~.gz</code></li><li><code>wget https://~~ict~~matrix.senecacollege.ca/~ops245~~/labs~~/centos4.xml</code></li></ul>

# Use gunzip with elevated privileges to decompress the qcow2 image file into the '''/var/lib/libvirt/images''' directory.

# Issue the command: <code>sudo virsh define centos4.xml</code>

# What happened in the virtual manager window? In order to remove a VM entry in the Virtual Manager window, simply issue the command '''virsh undefine VM_name''' without the '''.xml''' file extension

# Start up your new centos4 VM.

# Click on the user ~~OPS235~~OPS245, and click the cog icon.

# Notice Cinnamon (Software Rendering) is selected. The Cinnamon desktop environment has been installed on this VM. From this menu, you can select other installed desktop environments. This is how you switch between them. Write it down.

# Login with the password ~~ops235~~ops245. Feel free to explore the new environment.

# Prior to your practical test, you will be required to perform a similar operation to download, unzip and run a VM image for your practical test.

{{Admon/important|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. Note that it is better to shut down the VMs prior to shutting down the host}}<ol><li value="12">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...</li>

<ol>

<li>In your '''bin ''' directory, create the file '''backupVM.py''', and populate with our standard beginning

exit()

else:

~~for machine in~~ print('Backing up centos1~~','centos2','centos3~~'):   os.system('gzip < /var/lib/libvirt/images/centos1.qcow2 > ~YourRegularUsername/backups/centos1.qcow2.gz')   print('Backing up centos2' ~~+ machine~~)   os.system('gzip < /var/lib/libvirt/images/centos2.qcow2 > ~YourRegularUsername/backups/centos2.qcow2.gz')   print('Backing up centos3')   os.system('gzip < /var/lib/libvirt/images/~~' + machine + '~~centos3.qcow2 > ~YourRegularUsername/backups/~~' + machine + '~~centos3.qcow2.gz')

</code>

<li>It should print out root, but with an extra new-line. You may have noticed this in your other python scripts so far: the data we get from os.popen() has an extra new-line on the end. We will need to modify the string(s) it gives us a bit. See the side-bar for hints on how to do so.</li>

<li>Modify the if statement so it is just getting the current username, not the username and a newline. You can do this using several steps and several variables, but it can also be done in a single line.</li>

<li>Now that the script recognizes you as being root (or at least running the script with root permissions), it should work. Notice how we've used the + to combine several strings together to pass to the os.system command. We did this because this script needs the python variable to be evaluated before the whole line gets handed over to os.system. If you left the variable names inside the quotes, python will ignore them as just being part of a string. By putting them outside of a string, and concatenating their value to that string, we can evaluate them and feed them into that command.</li><li>Test your script to make sure it works. If it doesn't, go back and fix it. '''Do not continue until it successfully makes backups of your VMs'''.</li>

<li>There is a weakness to this script as written. Every time you run it, it will make a backup of all three VMs. But what if you only made a change to one of them? Do we really need to wait through a full backup cycle for two machines that didn't change? As the script is currently written, we do. But we can make it better. We've provided the scripts with some comments below.</li>

print("You must be root")

exit()

else

#The rest of this script identifies steps with comments 'Step <something>'.

#Step A: Find out if user wants to back up all VMs

#Step B-1:use the existing loop to back up all the VMs

~~for machine in~~   print('Backing up centos1',)   os.system('gzip < /var/lib/libvirt/images/centos1.qcow2 > ~YourRegularUsername/backups/centos1.qcow2.gz')   print('Backing up centos2',)   os.system('~~centos3~~gzip < /var/lib/libvirt/images/centos2.qcow2 > ~YourRegularUsername/backups/centos2.qcow2.gz'):   print('Backing up centos3' ~~+ machine~~)   os.system('gzip < /var/lib/libvirt/images/~~' + machine + '~~centos3.qcow2 > ~YourRegularUsername/backups/~~' + machine + '~~centos3.qcow2.gz')

#Step B-2: They don't want to back up all VMs, prompt them for which VM they want to back up

#Step C: Prompt the user for the name of the VM they want to back up

#Step C-3: If the user chose Centos3, back up that machine.

</code></li>

<li>Before the ~~for loop~~ block that backs up each machine add a prompt to ask the user if they want to back up all machines. Use an if statement to check if they said yes (See comment 'Step A').<ul><li>if they did say yes, back up all the VMs using your existing ~~for loop~~ block (Comment step B-1).</li><li>If they didn't say yes, do nothing for now(you could even use python's pass statement).</li></ul></li>

<li>Test your script to make sure it works. Check what happens if you say 'yes' to the prompt, and check what happens if you say things other than 'yes'.</li>

<li>Now we have a script that asks the user if they want to back up all VMS, and if they say they do , it does. But if they don't want to back up every VM, it currently does nothing.</li>

<li>Add an else statement at comment Step B-2 to handle the user not wanting to back up every VM. Inside that else clause (Comment step C) ask the user which VM they would like to back up (you can even give them the names of available VMs (Centos1, Centos2, Centos3).</li>

<li>Now nest an if statement inside that else (Comments C-1, C-2, and C-3) so that your script can handle what your user just responded with. If they asked for Centos1, back up Centos1. If they want to back up Centos2, only back up Centos2, etc. Hint: You might want to use elif for this.</li>

<li>Test your script again. You should now have a script that:<ul><li>Makes sure the user is running the script with elevated permissions.</li><li>Asks the user if they want to back up every VM.</li><li>If they want to back up every VM, it backs up every VM.</li><li>If the user does not want to back up every VM, the script asks them which VM they do want to back up.</li><li>If the user selected a single VM, the script will back up that one VM.</li><li>Now you may notice another issue with the script: The gzip lines are almost identical. The only difference in them is the name of the VM file being backed up. In the portion of code where you back up each machine individually (comment steps C-1, C-2, and C-3) try replacing the machine name in the gzip command with a string variable that holds the machine's name instead. Note that you will have to make us of string concatenation for this to work correctly.</li></ul></li>

</ol>

# Inside each virtual machine, run <code>ip a</code> on the command line. Open a Terminal window in centos1 to do so. You'll need the IP address of each machine for the next steps.

# Switch to your '''c7host''' VM, open a terminal, login as root, and change directory to '''/root/bin'''.

# Issue the Linux command: <code>wget https://~~ict~~raw.~~senecacollege~~githubusercontent.cacom/~~~ops245~~OPS245/labs/main/lab2-check.bash</code>

# 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''':<blockquote><ul><li>All 4 nested VMs '''created''' and '''running'''</li><li> Proof of '''yum updates''' on ALL VMs (i.e. results from '''yum update''' command)</li></ul></blockquote>

::✓'''c7host VM''':<blockquote><ul><li>Run the '''lab2-check.bash''' script in front of your instructor (must have all <code> OK </code> messages)</li></ul></blockquote>

::✓ Lab2 logbook notes completed.

Andrew

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