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Creating a virtual machine

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Overview

Teaching: 15 min
Exercises: 15 min
Questions

  • How do you create a virtual machine?

  • What is an OpenStack flavor?

  • What is a floating IP?

  • How can I allow SSH traffic into my virtual machine?

Objectives

  • Create a VM.

  • Associate a floating IP with a VM.

  • Add security rules to allow traffic into a VM.

  • Connect to a VM using SSH.

Creating a virtual machine

Now we will create your first virtual machine and connect to it using SSH. To do so go to the OpenStack dashboard and select from the left hand menu Compute->Instances and click Launch Instance button in the top right of the panel.

You are presented with a panel consisting of multiple tabs of fields to fill in. There are many optional fields which can allow additional functionality, but for this first exposure will stick to the basics.

Availability Zone: In theory this could allow you to chose how available you would like your VM to be. This would be done by launching your VM on hosts in a different availability zone which have certain hardware or software configurations which make them less susceptible to outages. However, on the Compute Canada cloud there is only one availability zone so there is no need to choose anything but the default.

Instance Name: specify the name of your virtual machine. OpenStack will attempt to use this name as the hostname of your virtual machine. However, if the instance name you provided is not a valid hostname OpenStack will modify it so that it is valid and use the modified version for your hostname while still referring to your VM in the OpenStack dashboard by the instance name you provided. As some of us are sharing a project, please include your name in the instance name, something like your-name-first-vm so that we don’t have VMs with duplicate names, it gets confusing.

What is a valid hostname?

A good description of a valid hostname is given in this wikipedia page section. The official specifications for hostnames are given in two Internet standards requests for comments documents RFC-952, and RFC-1123. The summary of the wikipeida page is, hostnames must be less than 64 characters long, contain only numbers letters and dashes (-).

Flavor: The flavor of your VM specifies the hardware profile your VM will have. Compute Canada cloud uses a consistent naming scheme across their clouds to describe the hardware profile. Examples of VM flavors are p1-1.5gb and c1-7.5gb-30 and the different components of the name correspond to different hardware features.

For this example choose the c1-7.5gb-30 flavor. Which is a compute flavor with 1VCPU, 7.5GB of RAM and a 30 GB of extra temporary disk storage.

Flavor variations

If you are on a different Compute Canada cloud, such as East cloud, you might have a different set of flavors, however you should still be able to pick something relatively close to this one. For example on East cloud a c1-3.7gb-36 flavor has about half the RAM but a slightly larger ephemeral data disk. For this workshop this flavor will work just as well.

Instance Count: indicates how many virtual machines, or instances, you wish to create. For this example choose 1.

Instance Boot Source: indicates from where your virtual machine will boot its operating system. There are several options to choose from, but for this example we will choose Boot from image. This choice indicates that we want to select an ephemeral disk as our boot source. The combination of the flavor we chose above and the boot source we chose instructs OpenStack to create a new virtual disk of 20 GB and copy the selected virtual disk image to it. This virtual disk will reside on the local disk of the host machine, or hypervisor, and contain the operating system files for the virtual machine.

Image Name: specifies an image which forms the starting point for our virtual machine. Usually this means choosing an operating system for your virtual machine. But it could include additional software packages and configurations also. We will choose the Unbuntu-16.04-Xenial-x64-2017-03 image which contains the Ubuntu Linux operating system, version 16.04.

Key Pair: The final piece of information we need to provide before creating a VM is the public key we created in the previous episode to allow you to connect to the VM you create. Select the Access & Security tab, then you can add a public key to your OpenStack account by clicking the “+” next to the Select a key pair drop down box. Then copy and paste in your public key into the text field. You can copy your public key text by going to your terminal where you created your key pair in the last episode and running the command

$ cat .ssh/id_rsa.pub

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCxo6H/dDFLunQOUKnTUxNfHTsDfARFdFjqyJrf2udOBAzm7hg/w4SaHAqF1b1DvmGhwKwXW6lXYkdsiA5d4IK/Cg8GZ7l74J1QTQ+e6JkdvOmVlTGnu6PTesd++6jZUeiF9Im0ksGPTYo8QH/5k1eHUMwWpUh9xfX0Z56IdUyNxx+/QaeCc61sUvIPf+w2Vm/zC44C+v5OX4lDWlamLf2b0u6be5L99UXWN8741354auMP8qVMidRq8jQjUmlto30b/2H9bMFGQ63eEApEnhe6s+qdxVlbLkKHT2H905ydXf4knAY3TGlgylBNbXjeiJEp9mKlQ5LnIi6rayxzDrIv cgeroux@Caelia

and copying this text into the Public Key text field on the OpenStack dashboard. Provide a Key Pair Name which will distinguish this key from other keys you might have, something like laptop-key or work-desktop-key. Then click the Import Key Pair button to add that public key to your OpenStack account. This public key can then be selected from the drop down box Select a key pair. This public key can also be used for other future virtual machines and across projects.

Before launching your first VM make sure to check the check box under Security Groups next to the default security group. This will add your VM to the default security group. A security group contains security rules that allow traffic into and out of your virtual machine. By selecting the default security group we can set rules to allow access to your virtual machine.

Finally click the Launch button at the bottom of the Launch Instance panel to create your first virtual machine!

Associating a Floating IP with a VM

To connect to your virtual machine you will need to associate a Public IP with your virtual machine. Doing so will create a pointer from a publicly accessible IP to your virtual machine. This publicly accessible IP is also known as a floating IP perhaps because the IP can “float” from one virtual machine to another. The public IP associated with your VM allows other machines to connect to your VM across the Internet. This is different from the private or local IP your VM gets by default, which only identifies the virtual machine on the local network.

To associate a floating IP with your newly created virtual machine:

The floating IP we just associated with your newly created VM will be the IP address we use to connect to your VM.

Different usage of the word “Port”

Earlier we talked about ports as numbers indicating a type of service for example a website or the HTTP service being associated with the port number 80. In this case the OpenStack dashboard is using the word port to refer to a virtual machine. Unfortunately this vagueness of how the word port is used can be a bit confusing.

Adding SSH Security Rule

To connect to the virtual machine we will be using SSH which communicates on port 22. To allow SSH connections into your virtual machine you will have to add a security rule to the default security group to allow it. To do this:

Connecting to a virtual machine

Once your virtual machine’s status as viewed on the Instances OpenStack dashboard panel is Active you can connect to your virtual machine using SSH. To do so run the following command

$ ssh ubuntu@206.12.11.12

in this command ubuntu is the username of the user you are connecting to the virtual machine as and 206.12.11.12 is the floating IP address of your newly created virtual machine.

Warning: Permanently added '206.12.11.12' (RSA) to the list of known hosts.
Enter passphrase for key '/home/mobaxterm/.ssh/id_rsa':
Welcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-71-generic x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

0 packages can be updated.
0 updates are security updates.



The programs included with the Ubuntu system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Ubuntu comes with ABSOLUTELY NO WARRANTY, to the extent permitted by
applicable law.

/usr/bin/xauth:  file /home/ubuntu/.Xauthority does not exist
To run a command as administrator (user "root"), use "sudo <command>".
See "man sudo_root" for details.

ubuntu@test:~$

At the bottom of the output you can see the prompt ubuntu@test:~$ this is now a shell prompt on the newly created virtual machine. Notice that the username we used to connect ubuntu is part of the prompt letting you know who the virtual machine thinks you are. Also notice test which is the hostname of your virtual machine, as mentioned earlier this derived from the Instance Name you give to your virtual machine. Finally the ~ indicates what directory you are currently in. In this case you are in the user ubuntu’s home directory.

From this point you can start working with or configuring your virtual machine with additional capability above and beyond those included in the basic Ubuntu operating system provided by the image we selected when creating our virtual machine. The things you can do with your new VM are only limited by your imagination, time, and OpenStack quota. Some examples of what you could do with your OpenStack VMS, run python scripts to scrape twitter data, run a wordpress site to publish articles, or do large scale text processing with Spark.

Disconnecting

To disconnect from a remote machine, or exit a shell, you can type the exit command.

What do you see in your VM’s log

The log of your virtual machine can be very helpful for understanding and debugging problems. On the Instances page then click on your Instance name and then the Log tab. The log shows various steps take and output generated while your VM is starting up and while running. Can you see where your public key is injected into the VM. Hint: it is put into a file called authorized_keys.

Solution

You should see something like the following:

ci-info: ++++++++++Authorized keys from /home/ubuntu/.ssh/authorized_keys for user ubuntu++++++++++
ci-info: +---------+-------------------------------------------------+---------+------------------+
ci-info: | Keytype |                Fingerprint (md5)                | Options |     Comment      |
ci-info: +---------+-------------------------------------------------+---------+------------------+
ci-info: | ssh-rsa | 24:8d:e7:a6:b8:f5:02:b1:0f:89:92:85:85:eb:d5:59 |    -    | rsa-key-20160303 |
ci-info: +---------+-------------------------------------------------+---------+------------------+

The comment associated with the public key is usually <user>@<hostname>. The Fingerprint can be used to uniquely identify the key pair and can be useful when trying to verify that a public key and a private key are part of the same pair.

What does the Console tab do

On the Instances page then click on your Instance name and then the Console tab. If it shows a blank or black box, try clicking on it and pressing the enter key.

Solution

It should show a login: prompt, prompting you to enter your username to login, but if you do it will ask you for a password but since we are authenticating using key pairs we don’t have a password. For this reason console is not very useful for Linux VMs. If you were to create a Windows VM though the authentication process is much different and the console becomes slightly more useful.

VM names to hostnames

If you were to create two VMs with names of _test and test!abs what would the hostname for the VM be?

Solution

the VM name will be modified to remove invalid characters. So a VM name of _test will become a hostname of test and VM name of test!abs will become testabs hostname. When you log into a VM you see the hostname and not the VM name at the command prompt.

Key Points

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