In this post we’ll see how to work with Jinja2 in your Python projects, to easily create and modify templates.
Jinja2 is widely used and you probably already noticed it if you used projects such as Flask and Ansible or even if you simply searched for a robust templating engine.I can describe its greatness for a couple of minutes if not hours, but the
I can describe its greatness for a couple of minutes if not hours, but the official doc does it much better, so I recommend to go over them to get an idea on what you can achieve by using it. This post is mainly for those who are looking for a quickstart guide.
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.
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.