Although you have already seen an OpenStack cloud in action,
and you have seen me build a two-tier application,
this application still needs a lot of work, so without further ado,
let's do it.
Most of this presentation is actually a demo.
What are we going to cover? We will see how instances can be accessed
on the console and over the network. For network access,
instances need to open ports in their firewall.
In order to access instances interactively, you'll certainly want to
avoid passwords, especially if you have to manage hundreds or even
thousands of instances. Finally, instances need to store data
somewhere, and normally that data should survive the instance.
When the instance goes away, we still need the data, how can we do that?
We will start with our two-tiered application, and the first thing we
do is we will check how we can access an instance over the console.
Let's start with the old familiar network topology, the two networks
and the two servers. I will now try to find out how to interact with
the web server. But to do that, I will first switch to the other
network view, a more static view, easier in a presentation mode.
Now this web server seems to be shut off, and that is so because I
rebooted the Packstack host. In order to revive it, I have to go to
the instance details. And here we are, the instance details of webserver1.
Now to start it, I will click this button here, that looks good,
that looks perfect. Let's do the same thing with the other server as
well, it has been shut down as well. Let's go back to the details,
I want to interact with this server, and I can do that by clicking on
the Console tab. This gives me the Instance Console.
Sometimes it doesn't react when you hit Return here, so I will just
click on that gray bar once, and then usually it can be used.
Here it goes. Let's log on as cirros, and the password is also shown
here on the screen. Now this is a simple Linux system, let's run a
few commands such as listing all the storage.
Remember the flavor gave us a storage size of 1 GB, we can also look
up the networking, and you can see here the IP address.
In addition to this interactive console, the instance also has a log
file here, which shows us the messages from its start until the login prompt.
Let me go to the end, this is the login prompt, this is perhaps hard
to read, so let me increase the size a little bit.
Now this is not the full log, and if you want to see everything,
just click on this button, and in a new window, we see the full log.
Here is the networking information together with the IP address again.
A bit further out, we see how the Secure Shell Host keys have been set up.
Scrolling one page up, this is the SSH daemon, so it looks like we can
actually communicate with the instance via SSH.
And finally, up here you can see how the instance actually go its IP
address, it happened via DHCP. Before we move on, let me just state
that of course not all instances have this same initialization log,
it really depends on the kind of image operating system from which
they were provisioned.