TuxLabs

All things DevOps

Tag: JSON

Fun with Python, Tabular & AWS IP ranges

Published March 09, 2016 / by tuxninja / Leave a Comment

I have been spending a lot of time designing a Hybrid Cloud that consists of Openstack and public cloud platforms. In particular I have been spending a lot of time designing the AWS portion of the Hybrid Cloud Platform. Today I found myself continually needing to look up AWS public address space and then parsing out regions & services. Then I remembered something a mentor of mine told me…

if you are going to do something more than once, there is probably value in automating it.

I love writing command line tools and thus a short Python script was born. Since I rarely share Python code, even though I didn’t spend a lot time on this, and I certainly didn’t optimize it for DRY etc. I am sharing it anyway for others to use, enjoy and hack on,

but mainly to learn, which is…The entire purpose of the Tuxlabs site

I should mention I have strong views about when to use Python vs. Go a language I find myself writing in more and more and this tool falls under my rules for things that I should write in Go. So later as a follow up I will likely re-code this in Go and post the code for review & learning. For now here’s the Python code, enjoy !

Listing all IP Ranges

Filtering

The code

Posted In AWS | Cloud | Programming | Python
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How To: curl the Openstack API’s (v3 Keystone Auth)

Published February 19, 2016 / by tuxninja / Leave a Comment

While Openstack provides a python client(s) for interactions….

I frequently, finding myself needing to get data out of it without the pain of awk/sed’ing out the ASCII art.

Thus to quickly access the raw data, we can directly query the API’s using curl & parsing JSON instead, which is much better 🙂

Authentication

Before we can interact with the other Openstack API’s we need to authenticate to Keystone openstack’s identity service. After authenticating we receive a token to use with our subequent API requests. So step 1 we are going to create a JSON object with the required authentication details.

Create a file called ‘token-request.json’ with an object that looks like this.

Btw, if you followed my tutorial on how to install Openstack Kilo, your authentication details for ‘admin’ is in your keystonerc_admin file.

Now we can use this file to authenticate like so:

The token is actually returned in the header of the HTTP response, so this is why we need ‘-i’ when curling. Notice we are parsing out the token and returning the value to an environment variable $TOKEN.

Now we can include this $TOKEN and run whatever API commands we want (assuming admin privileges for the tenant/project)

Curl Commands (Numerous Examples!)

I sometimes pipe the output to python -m json.tool, which provides formatting for JSON. Lets take a closer look at an example.

Listing servers (vm’s)

I only have 1 VM currently called spin1, but for the tutorials sake, if I had ten’s or hundred’s of VM’s and all I cared about was the VM name or ID, I would still need to parse this JSON object to avoid getting all this other meta-data.

My favorite command line way to do that without going full Python is using the handy JQ tool.

Here is how to use it !

The first command just takes whatever the STDOUT from curl is and indent’s and color’s the JSON making it pretty (colors gives it +1 vs. python -m json.tool).

The second example we actually parse what were after. As you can see it is pretty simple, but jq’s query language may not be 100% intuitive at first, but I promise it is pretty easy to understand if you have ever parsed JSON before. Read up more on JQ @ https://stedolan.github.io/jq/ & check out the Openstack docs for more API commands http://developer.openstack.org/api-ref.html

Hope you enjoyed this post ! Until next time.

 

 

Posted In Cloud | How To's | Openstack | Systems Administration
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