[just.few.tuts] Beginner’s Guide to OpenStack : Basics of Nova #Part.2

@ justfewtuts.blogspot.com []

http://justfewtuts.blogspot.in/2013/04/beginners-guide-to-openstack-basics-of.html

parts of Beginner’s Guide to OpenStack to read before this ~

Part1: Basics

[Part.2 Basics of Nova] Beginner’s Guide to OpenStack

# Nova?
It’s the main fabric controller for IaaS providing Cloud Computing Service by OpenStack. Took its first baby steps in NASA. Contributed to OpenSource and became most important component of OpenStack.
It built of multiple components performing…..

# Components?
Nova stores states of virtual machines in a central database. It’s optimal for…..

# API Style
Interface is mostly RESTful. Routes (python re-implementation of Rails route system) packagesmaps URIs to…..

# Threading Model
Uses Green Thread implementation by design using eventlet and greenlet libraries. This results into single process thread for O.S. with it’s blocking I/O issues. Though…..

# Filtering Scheduler
In short it’s the mechanism used by ‘nova-scheduler’ to choose the worthy nova-compute host for new required virtual machine to be spawned upon. It prepare…..

# Message Queue Usage
Nova components use RPC to communicate each other via Message Broker using PubSub. Nova implements rpc.call (request/response, API acts as consumer) and rpc.cast (one way, API acts as publisher)…..

…..

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[just.few.tuts] Beginner’s Guide to OpenStack : Basics #Part.1

@ justfewtuts.blogspot.com [17/Apr/2013]

http://justfewtuts.blogspot.in/2013/04/beginners-guide-to-openstack-basics.html

# OpenStack?
OpenStack (http://www.openstack.org/) is an OpenSource cloud computing platform that can be used to build up a Public and Private cloud. As in weaving of various technological components to provide a capability to…..

# Quick Hands-On
DevStack (http://devstack.org/) gives you the easiest fastest way to get all OpenStack components installed,…..

# Components?

OpenStack Cloud Platform constitutes of mainly following components:
…..

Message Queue Service is used by most of the OpenStack Compute services to communicate with each other using AMQP (Advanced Message Queue Protocol) supporting async calls and callbacks.
—
# Weaving of Components

asciigram: openstack ~ evolution mode, how varied components are connected

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[tekwalk] console and json

@ tekwalk.blogspot.com [12/Apr/2013]

http://tekwalk.blogspot.in/2013/04/console-and-json.html

recently Alan posted a very nice aticle around prettifying json, reminded me of <this draft>… he posted 2 out of 3 utilities I was gonna mention… so here is 3rd and the shell profile way to use first 2

$ sudo wget -c -O /etc/profile.d/a.json.sh https://raw.github.com/abhishekkr/tux-svc-mux/master/shell_profile/a.json.sh

it contains 2 functions available at shell

# usage example:
# $ json_me ‘echo {“a”: 1, “b”: 2}’
# $ json_me ‘curl http://127.0.0.1/my.json&#8217;
json_me(){
bash -c $@ | python -mjson.tool
}

# requirement: $ pip install pjson
# usage example:
# $ pjson_me ‘echo {“a”: 1, “b”: 2}’
# $ pjson_me ‘curl http://127.0.0.1/my.json&#8217;
pjson_me(){
bash -c $@ | pjson
}

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[tekwalk] make rvmsudo use running user’s ENV var

@ tekwalk.blogspot.com [8/Mar/2013]

http://tekwalk.blogspot.in/2013/03/make-rvmsudo-using-running-users-env.html

…..

While running ‘rvmsudo chef-solo ….’, it picks desired user but because of $HOME inference in the ‘nvm/install.sh’ still the HOME value got picked for ‘/root’. It messed up the situation.

To fix it, and any certain issues around permission which might occur… using

$ rvmsudo USER=$USER HOME=$HOME chef-solo -j….

it’s working with desired output.

Though…..

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[just.few.tuts] MessQ : message queue for quickly trying any idea

@ justfewtuts.blogspot.com [3/Feb/2013]

http://justfewtuts.blogspot.in/2013/02/messq-message-queue-for-quickly-trying.html

Past some time while trying up some set-up based on Message Queue at infrastructure… needed a quick to set-up, localhost friendly, network available Message Queue service to try out ideas.
So here is Mess(age)Q(ueue). Something quickly thrown together. Would work later to get it more performance oriented, good to go with smaller projects.

@GitHub:       https://github.com/abhishekkr/messQ
@RubyGems: https://rubygems.org/gems/messQ
_________________________

A Quick Tryout

[+] Install
$ gem install messQ –no-ri –no-rdoc
[+] Start Server (starts at 0.0.0.0 on port#5566)

$ messQ –start

[+] Enqueue user-id & home value to the Queue

$ messQ -enq $USER

$ messQ –enqueue $HOME

[+] Dequeue 2 values from Queue

$ messQ -deq

$ messq –dequeue

[+] Stop Server

$ messQ –stop

_________________________

Via Code….

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[tekwalk] Apache httpd VirtualHosts : one gets default, unknown faults

@ tekwalk.blogspot.com [13/Jan/2013]

http://tekwalk.blogspot.in/2013/01/apache-httpd-virtualhosts-one-gets.html

Recently faced a situation where even after removing a VirtualHost, its ServerName was giving HTTP 200 response. It was all because of missed RTFM agenda.

When VirtualHosts get applied in Apache HTTPD server configuration, the first definition encountered by Apache Controller gets selected as the default route logic selected if the ServerName doesn’t match any provided.

example scripts at https://gist.github.com/abhishekkr/4526414

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[a.Bionic] shell.function to auto-clone all Repositories from a GitHub account

@ abionic.blogspot.com [13/Jan/2013]

http://abionic.blogspot.in/2013/01/shellfunction-to-download-all.html

a shell utility to download all repositories managed under any GitHub account in the current directory…
if the current directory has any of the repositories already cloned, it pulls the latest

usage:   $ clone-github github
would download all the repositories managed under ‘github’ account

shell function at https://gist.github.com/abhishekkr/4428447/raw/7afb0cc878b6c95d6af37dcdd5e13f62a00befdb/a.github.sh

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