Arie Bregman

Linux And Stuff

Author: bregman (page 1 of 7)

InfraRed: Deploying and Testing Openstack just made easier!

Deploying and testing OpenStack is very easy

If you read the headline and your eyebrows raised, you are at the right place. I believe that most of us, who experienced at least one deployment of OpenStack, will agree that deploying OpenStack can be a quite frustrating experience. It doesn’t matter if you are using it for debugging your code or it’s an integral part of your CI environment, deploying OpenStack often with changes, can be complex. Let’s stop for a minute and think why it’s like that.

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TripleO: Debugging Overcloud Deployment Failure

You run ‘openstack overcloud deploy’ and after a couple of minutes you find out it failed and if that’s not enough, then you open the deployment log just to find a very (very!) long output that doesn’t give you an clue as to why the deployment failed. In the following sections we’ll see how can we get to the root of the problem.

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Python: check if two strings are permutations of each other

Another question I cover in a presentation I’m preparing for “Open University meets Open Source” meetups.

What is a Permutation?

Permutation is the action of rearranging objects, characters or symbols into different, unique sequences.

Each sequence is called ‘permutation’.

It’s common to see people mix permutation with combination, but those are two different things. Remember, combination doesn’t care about the order, while permutation does.

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Python: check if one string is a rotation of another string

Another question I cover in a presentation I’m preparing for “Open University meets Open Source” meetups.

The question

You have two strings, str1 and str2 and you need to return True if the first string is a rotation of the second string. Otherwise, return False.

Examples

“hello”,    “llohe” -> True. If we’ll rotate the second string twice, you’ll get ‘hello’.

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OpenFlow: Introduction

What is OpenFlow?

If we tried to explain what OpenFlow is, a possible definition would be: OpenFlow is a protocol for controlling and interacting with forwarding behaviors of switches. It allows us to dynamically control  the behavior of the switches in our network. Many SDN (software defined network) and Open Source projects use OpenFlow or support it as a plugin, such as OpenStack Neutron and OpenDaylight.

But It’s hard to grasp what it is, what it solves and how it works only using this brief description. In order to truly understand what is OpenFlow, we need to start from the beginning, before SDN era.

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