This is a first draft awaiting review 10/18/2016
This is a walk through for new Nebula users who are unfamiliar with OpenStack to help them create their first instance. An instance is a virtual machine (VM) that you control as if it were an independent server. The Nebula FAQ contains information about how to get an account on Nebula and is a source for more general information. Once you have an account, go to http://nebula.ncsa.illinois.edu in a browser and log into the NCSA Nebula cluster through its OpenStack Horizon Interface. After logging in, you will see your project space on Nebula with main menu options on the left and an overview of your project's resource usage:
The second Panel of the Launch Instance interface allows you to secure your instance. In order to get access to your instance with ssh you will need to specify a Key Pair for it to use.
<GIVE DIRECTIONS FOR HOW TO UPLOAD OR CREATE A KEY PAIR AND HOW TO USE THEM>
On the remote Linux machine you are going to use to ssh into your new instance, check if the file $HOME/.ssh/id_rsa.pub already exists. If it does not already exist, execute “ssh-keygen –t rsa” which will prompt you for a location (press Enter) and for a passphrase. You can leave the passphrase blank by pressing Enter although having one is an added layer of security.
Now that you have a public key, select the “+” button next to the “Key Pair” drop down box. This will open a popup window “Import Key Pair”. Enter a “Key Pair Name”, including the name of the remote machine would be helpful when you need to use the key pair in the future. Paste the contents of the $HOME/.ssh/id_rsa.pub file into the “Public Key” input box in the window. Select the “Import Key Pair” button, the popup window will close and you will see the "Access & Security" tab again. The new key pair should now be displayed in the “Key Pair” field.
From this panel you will also need to specify what Security Groups will be associated with your instance. These security groups set what traffic the nova router, which is internal to OpenStack, allows to flow to and from your instance. They do not configure the iptables internal to your instance. To enable ssh access into the instance after startup, select the remote SSH security group. If the instance may run web servers/services, select remote HTTP to ensure that the standard ports will be open. As with flavors, other security groups can be defined by your project and will be available to you. You can edit which security groups your instance uses after it is created.
The third Panel involves networking. If your project only has access to one network it will already be selected for you and you don't need to do anything here. If other networks are available for your project they can be selected or dragged into the "Selected networks" box. It is possible to create user-defined networks and attach instances to such networks, though this case would be for specific applications and is beyond our current scope.