Automating OpenStack and Rackspace Servers Administration with Python, 1st ed. [Kindle Edition]

The Basics

The OpenStack Compute API is written in the Python programming language and requires a Python interpreter on the system where you will be using it. The Python interpreter does not have to be installed on the Rackspace/OpenStack virtual machines, just the one you will be using to communicate with your Rackspace/OpenStack cloud.

We will now discuss the OpenStack Compute API setup process.

Installing Python On Your Machine

Python is a very popular scripting language that ships pre-installed on Mac OS X and some Linux distributions. You can verify if and which version of the Python interpreter you have installed on your system with the following command (must be issued on the command line, do not type the dollar sign):

$ python --version

The version you need is at least 2.6.1.

If you are working in a graphical user interface environment and you are not sure how to get to the command line, do the following:

If you do not have Python installed on your system or it is not the version we need to run the OpenStack Compute API, you will need to add a Python interpreter to your system by hand. Fortunately, Python installation packages exist for all popular operating systems, and if you cannot get one for your favorite system, you can usually build it from the sources. You can download the Python interpreter binaries and sources from the official download page:

http://python.org/download/

If your favorite operating system is not listed on that page, refer to your system’s documentation for information on adding external packages. Various variants of Unix have their own packaging systems that make sure the software you install is properly configured on your system. For example, the right way to add Python to Ubuntu Linux is via the apt-get command:

$ sudo apt-get install python

Whenever possible, use the pre-made packages. You can always build software from the sources, but it should not be necessary in this case.

If you are installing Python on a Microsoft Windows Machine, you may have to add the path to the Python interpreter to the Path environment variable. On a Microsoft Windows 7 system, you will need to open the Environment Variables dialog. You can do it in the following way:

  1. Click the Start button.
  2. Right-click on the Computer menu item.
  3. Select Properties.
  4. Select Advanced System Settings.
  5. Click the Environment Variables button.
  6. Click on the Path entry on the System Variables list.
  7. Click the Edit button.
  8. Add ;C:\Python26 to the end of the string shown in the text field of the edit dialog.
  9. Click the OK button.

Please check the real path to the Python interpreter on your system. You can do that by browsing the system disk. Look for the topmost path whose name begins with Python.

Installing the OpenStack Compute API Python Module

The openstack.compute aka. OpenStack Compute API Python module can be found on GitHub:

https://github.com/jacobian/openstack.compute

Click on the Downloads link and choose the archive format you like best. You have a choice of .zip and .tar.gz.

Handling .zip Archives

If you download a .zip file, you will need to unpack it using the unzip command on a Mac OS X, Linux, or other Unix-like operating systems:

$ unzip tar zxvf jacobian-openstack-compute-xxxxxxx.tar.gz

Double-clicking on a .zip file in Microsoft Windows 7 or Mac OS X will do the same trick.

Handling .tar.gz Archives

The .tar.gz format is popular on Unix-like systems and you can unpack it with the following command:

$ tar zxvf jacobian-openstack-compute-xxxxxxx.tar.gz

Double-clicking on a .tar.gz file in Mac OS X will do the same trick. Results of double-clicking on .tar.gz files in Microsoft Windows are unpredictable, please use .zip archives.

Installing the OpenStack Compute API Python Module

Once you are done unpacking the archive, you need to enter the directory where the unpacked OpenStack Compute API files are now located (replace xxxxxxx with the string added to the name of the archive you have downloaded from GitHub). You do it in the following way: 

$ cd jacobian-openstack-compute-xxxxxxx

In the next step you will install the OpenStack Compute API for system-wide use. On Mac OS X, Linux, or other Unix-like operating systems, you need to issue the following command:

$ sudo python ./setup.py install

There is no sudo on Microsoft Windows, all you need to type is:

> python ./setup.py install

Congratulations! You are done setting up your environment for OpenStack Compute API module.

Getting the API Key

In order to use the OpenStack Compute API you will need to have your own unique API key, which you can only get if you are a Rackspace customer. At least that’s how things look like today, in May 2011; in the future, when OpenStack will be offered by other vendors, you will be able to obtain that key from your OpenStack vendor of choice.

Fortunately, unlike real servers that you either buy or rent, virtual servers offered by Rackspace are very affordable and you can start experimenting with them on a very low budget.

To begin your journey, go to http://www.rackspace.com/cloud/ and open an account for Cloud Servers and Cloud Files. Without Cloud Files, Rackspace will not issue the API key required to run examples in this book.

Opening an account with Rackspace is a simple process if you are based in the USA, because Rackspace is a US company. International customers should expect that Rackspace employees will do additional checks on them, so be patient and if you do not get your account activated within a few hours, send a polite email to the support department, and be prepared to have a short conversation on the phone when they call you back to confirm that you are real. This is inconvenient, but it is necessary. Acting like the angry android from the movie Bladerunner is not the way to handle this situation.

Once you have your account up an running, click on the Your Account link in the Cloud Control Panel. Then, click on the API Access item on the menu. The API key is hidden. You need to click on the Show Key button, copy the key from the API Key field and paste it into your script.

Please make sure that the scripts you are pasting the key into are not readable by other users because the API key is literally the key to your account and with it anyone who gets a hold of it will be able to wreak havoc with your cloud. If you suspect that the worst might have happened, go back to the API key page and click on the Generate New Key button. It will make all scripts, safe and rouge, inoperable, so once you cut them off, fix the security holes and then replace the old key with the new one in your own scripts.

Using the openstack-compute Shell Utility

The best way to get started with the OpenStack Computer API without having to learn Python is the openstack-compute utility. You get it as a part of the OpenStack Compute API module source code download. It wraps the API in a familiar Unix command interface. That way you can start using the API without having to learn Python and you can use it as a part of a Bash or other shell script.

Setting Up the Local Environment for the OpenStack Compute API

Like almost any Unix command, openstack-compute uses environment variables and apart from the usual ones, already set on your system, it needs two of its own:

Setting Environment Variables On a Unix-Like System

When you are using Linux, Mac OS X, or another Unix-like operating system, you will need to issue the following commands:

$ export OPENSTACK_COMPUTE_USERNAME=putyourusernamehere
$ export OPENSTACK_COMPUTE_API_KEY=putyourapikeyhere

You will quickly get tired of doing that by hand every time you start a new command-line session. If you want to automate this step, add the following two lines to your ~/.profile file using a plain text editor like vi or nano:

export OPENSTACK_COMPUTE_USERNAME=putyourusernamehere
export OPENSTACK_COMPUTE_API_KEY=putyourapikeyhere

Save the modified ~/.profile. Close the terminal window and open it again. The variables should now be set. You can verify that with these commands:

$ echo $OPENSTACK_COMPUTE_USERNAME
$ echo $OPENSTACK_COMPUTE_API_KEY

Setting Environment Variables On Microsoft Windows

On a Microsoft Windows 7, you will need to open the Environment Variables dialog. You can do it in the following way:

  1. Click the Start button
  2. Right-click on the Computer menu item
  3. Select Properties.
  4. Select Advanced System Settings.
  5. Click the Environment Variables button.
  6. Click the New button under the User variables list and define the value of OPENSTACK_COMPUTE_USERNAME (use uppercase for the variable name).
  7. Click the New button under the User variables list and define the value of OPENSTACK_COMPUTE_API_KEY (use uppercase for the variable name).
  8. Exit the Environment Variables dialog.
  9. Start a new command line interpreter (see the instructions in the previous section).
  10. Type set OPENSTACK_COMPUTE_USERNAME to verify that the variable is set properly.
  11. Type set OPENSTACK_COMPUTE_API_KEY to verify that the variable is set properly.

Important Security Information

Whenever you store your user name and API key in an unencrypted file, you are making it easier to capture your Rackspace/OpenStack credentials. Please make sure that you protect your account and the API key information in the following way:

Remember! Anyone who knows your username and the API key can have full control over your cloud.

If you suspect that the API key has gotten into wrong hands, log in to your Rackspace account and generate a new key using this procedure:

Testing openstack-computing

Once the OpenStack Compute API environment variables are set, you can check if openstack-computing is working properly using the following command:

$ openstack-compute flavor-list

If you decide to not set the OpenStack Compute API environment variables, you can still run the openstack-computing command, but you must provide your Rackspace / OpenStack credentials on the command line:

$ openstack-compute --username yourusername --apikey yourapikey flavor-list

Either way, if all is working properly, you should see a table similar to the one shown below:

+----+---------------+-------+------+
| ID |      Name     |  RAM  | Disk |
+----+---------------+-------+------+
| 1  | 256 server    | 256   | 10   |
| 2  | 512 server    | 512   | 20   |
| 3  | 1GB server    | 1024  | 40   |
| 4  | 2GB server    | 2048  | 80   |
| 5  | 4GB server    | 4096  | 160  |
| 6  | 8GB server    | 8192  | 320  |
| 7  | 15.5GB server | 15872 | 620  |
+----+---------------+-------+------+

This confirms that you have set up your environment correctly. If something’s wrong, you will see the following message:

Invalid Cloud Servers credentials.

You need to check your username and API key settings and try again.

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