My Experience With Programming by G S Rao

Enabling password authentication for new ec2 box | ssh, ssh config, EC2 setup, new user in EC2, PasswordAuthentication

2016-07-07T23:43:00.002-07:00

Your EC2 box only contain .pem auth to enable password authentication follow the steps

By default your ec2 box come with .pem authentication, once you create your user and password for that user you can’t able to login with that credentials because EC2 by default disables that functionality.

Edit ssh config file by below command

$ sudo vim /etc/ssh/sshd_config

Search for PasswordAuthentication setting and setit to yes

PasswordAuthentication yes

Restart ssh server

$sudo /etc/init.d/ssh reload

Deployment instructions using github hooks to Ec2 or any cloud VS like HEROKU does | deployment, github hooks, heroku, set production server, set server, EC2

2016-07-07T23:42:00.003-07:00

Prepare your github repo on /var/www folder to follow the best practice.

$cd /var/www

Create a source code folder with your application name

$ sudo mkdir <Project Name>.com

Create a folder for github source code

$ sudo mkdir <Project Name>.com.git

Change to project github repo folder

$cd img-cloud-qa.com.git/

Initiate github bare to prepare folder

$sudo git init --bare

Jump to hooks to prepare your hooks for git preparation of project so you can start pushing your code to github.

$cd hooks

Now we are ready with hooks set to your project, create a post-receive file to execute your steps with shell script, below example is a node project and i am doing npm install and restarting web server.

$sudo nano post-receive


#!/bin/sh

error_exit ()
{
echo "$1" 1>&2
exit 1
}

git --work-tree=/var/www/<Project Name>.com --git-dir=/var/www/<Project Name>.com.git checkout -f
cd /var/www/<Project Name>.com || error_exit "error changing directory!. now exiting..."
npm install || error_exit "error running npm install! now exiting ..."
FOREVER_ROOT=/etc/forever forever restart -l /etc/forever/<Project Name>.log bin/www || error_exit "error starting forever server! now exiting ..."

Finally assign the proper permissions to the user to write files to to folder

$sudo chown -R deploy:deploy www/

Once all above steps done you are ready to deploy push your code to your project with below steps

git add remote <user>@<ip or host>:/var/www/<Project Name>.com.git
git push master

Ex:-

git add remote prod deploy@gsrao.xyz:/var/www/myapp.com.git
git push prod master

Ruby on Rails 3.x Skip callback and validation and reset Callback | Ruby on Rails, Skip callback, validation, reset Callback

2016-07-07T23:42:00.000-07:00

This will work for Rails 3.x onwords

Model.skip_callback(“create”,:after,:trigger_my_method)

in the above line ‘create’ and ‘after’ represents callback name so it represents ‘after_create’ callback, and the callback method is ‘trigger_my_method’, so totally the above line skips below callback

after_create :trigger_my_method

You can skip validations just by passing :validate => false as parameter to save method

Model.save(:validate => false)

As before skipping callback, you can reset same callback for reset by below ling

Model.set_callback(“create”,:after,:trigger_my_method)

This line will reset the below callback

after_create :trigger_my_method

Example:-

Skip callback and validation and rest the skiped callback

Post.skip_callback(“create”,:after,:trigger_my_method)

post=Post.new(params[:post])

post.save(:validate => false)

Post.set_callback(“create”,:after,:trigger_my_method)

Ruby one of the method of creating a single ton method | Ruby, single ton method

2016-07-07T23:41:00.004-07:00

cat = String.new("cat")
def cat.speak
    'miaow'
end
cat.speak #=&gt; "miaow" 
cat.singleton_methods #=&gt; ["speak"]

Ruby Rightsignature API to prefill the template | Ruby, Rightsignature, API to prefill template

2016-07-07T23:41:00.000-07:00

For this Please signup with https://rightsignature.com/ to get your api key and secrets

Generate a new API key by the url https://rightsignature.com/oauth_clients/new

Install rightsignature-api gem by the command

gem install rightsignature-api

gem ‘rightsignature-api‘ in your gem file

Setup your api with secret key by the code

@rs_connection = RightSignature::Connection.new(:api_token =&gt; YOUR_TOKEN)

 You can view the list of templates by the code

@rs_connection.templates_list

If you want to  view more details of template

@rs_connection.template_details(guid)

You need to Clone a template to fill and send the template as a document

@rs_connection.prepackage(guid)

Pre fill the required templates by the code (wre need to use merge fields to fil the data, you can't use the text fields to pre fill)

@rs_connection.prefill(guid, subject, roles, options={})

Send the template to signature by the code

@rs_connection.send_template(guid, subject, roles, options={})

Note:- We can prefill only merge field not text or other field

 Merge field is found while creating a template, is shown in below image

 https://rightsignature.com/oauth_clients/new

My router blocking facebook and youtube video play only for my laptop not other laps in same network, my lap works if i bypass modem. | router, blocking, facebook, youtube, video play

2016-07-07T23:40:00.002-07:00

Question : I have reset factory settings, reboot my modem, pc, clear cache, etc. still its not loading facebook but will load any and all other websites. When i bypass the router, connect directly to my modem, facebook works. why is this happening?

Solution : It is because of TCP packet size for that we need to change the MTU size of our tcp connection, below commands will help to do that

$ifconfig

above command will display the available networks with name and if addrsss

Ex:-

$ifconfig

eth0 Link encap:Ethernet HWaddr b8:ca:3a:d4:63:1d
UP BROADCAST MULTICAST MTU:1492 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:65536 Metric:1
RX packets:776 errors:0 dropped:0 overruns:0 frame:0
TX packets:776 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:79415 (79.4 KB) TX bytes:79415 (79.4 KB)

wlan0 Link encap:Ethernet HWaddr 60:6c:66:26:6c:9f
inet addr:192.168.2.101 Bcast:192.168.2.255 Mask:255.255.255.0
inet6 addr: fe80::626c:66ff:fe26:6c9f/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:50480 errors:0 dropped:0 overruns:0 frame:0
TX packets:42606 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:58833138 (58.8 MB) TX bytes:6534754 (6.5 MB)

In above my current network is wlan0 with ip 192.168.2.101

So now we need to change MTU for wlan0 with below command

$sudo ifconfig wlan0 mtu 1492

That will reset the MTU to 1492 and my problem solved.

Rails working with multiple databases customize the generator | Rails, multiple databases, customize generator

2016-07-07T23:39:00.005-07:00

In ROR working with multiple databases ( Mysql + MongoID or Postgres + MongoId ) for performance is good, but how can i give default generator database to pick-up while generating the models

edit application.rb in config folder and add below code

config.generators do |g|
g.orm :active_record

end

So every time in next generators will take active record as default for moddels

In case of using mongoid and active record this will be helpful

ROR HEROKU Working with file storage like paperclip in heroku for free of cost ( paperclip and dropbox) paperclip-dropbox config | ROR, HEROKU, file storage, paperclip, in heroku, free of cost, paperclip, dropbox, paperclip-dropbox config

2016-07-07T23:39:00.002-07:00

In my project i am using paper-clip and deployed to heroku, heroku not allows the file storage but to use aws normally, i don’t want to spend money so i can use drop box storage which will gives 2gb free storage space.

So i am using paper-clip with drop box with library papercklip-dropbox gem, steps to follow are given below.

Include gem “paperclip-dropbox” in your gem file
Run the command $bundel install
Create drop box api app in https://www.dropbox.com/developers/apps and give read write permissions it gives you the App key and App secret which will used in further configeration
Generate the other required details using available details, run the rake task to generate other details “$rake dropbox:authorize APP_KEY=your_app_key APP_SECRET=your_app_secret ACCESS_TYPE=your_access_typ “, this command will generate the access_token, access_token_secret, user_id
Create dropbox_config.yml file in config folder and place all keys got in previous steps
app_key: YOUR_APP_KEY
app_secret: YOUR_APP_SECRET
access_token: YOUR_ACCESS_TOKEN
access_token_secret: YOUR_ACCESS_TOKEN_SECRET
user_id: YOUR_USER_ID
access_type: “app_folder”
Now relace paper clip code with new code for attachment, like User profile picture
#added for paperclip-dropbox gem
has_attached_file :picture,
:storage => :dropbox,
:dropbox_credentials => “#{Rails.root}/config/dropbox_c
onfig.yml”,
:styles => { :medium => “300×300” , :thumb => “100×100>”},
:dropbox_options => {
:path => proc { |style| “#{Rails.env}/#{style}/#{id}_#{picture.original_filename}”}, :unique_filename => true
}
Deploy your code in heroku you can, you can see all files or images uploaded as profile pictures will store in your drop box.

Enjoy the drop box free usage in cloud

AngularJS e2e Testing Using Protractor and automate Grunt Task, with useful code modules | e2e, Testing, Protractor, automate Grunt Task

2016-07-07T23:38:00.002-07:00

Please check my post on my company blog post on AngularJs e2e testing.

Mobile Android development api with ruby language

2012-04-07T11:28:00.000-07:00

please follow the below link

http://ruboto.org/

Ruby on Rails enable history in ajax calls

2012-03-28T10:09:00.001-07:00

Refer below link

http://lindsaar.net/2008/2/21/history-buttons-with-ajax-and-ruby-on-rails

and use the code

window.dhtmlHistory.create({

	toJSON: function(o) {
	return JSON.stringify(o);

	} , fromJSON: function(s) {

	return JSON.parse(s);

	}

	});

instead of

window.dhtmlHistory.create({   toJSON: function(o) {     return Object.toJSON(o);   },   fromJSON: function(s) {     return s.evalJSON();   } });

on that post  Happy learning

Hacking and Crackers Knowledge

2012-03-20T10:07:00.001-07:00

Following are the importent web sites to know hackers and crackers

Vulnerability Research
Websites

www.securitytracker.com
www.microsoft.com/security
www.securiteam.com
www.packetstormsecurity.com
www.hackerstorm.com
www.hackerwatch.org
www.securityfocus.com
www.securitymagazine.com
####################################################
Securitytracker

www.securitytracker.com
#####################################################
Securiteam
(www securiteam com)
www.securiteam.com)
###################################################
Secunia (secunia.com/product/)

####################################################
Hackerstorm Vulnerability Database
Tool (www.hackerstorm.com)
####################################################
SecurityFocus
www.securityfocus.com
####################################################
SecurityMagazine
www.securitymagazine.com
#######################################################
SC Magazine
www.scmagazine.com
####################################################
http://www.usdoj.gov (cont'd)
#####################################################

Rails Memcache issues

2012-03-20T02:44:00.001-07:00

Error :-
down_retry_delay not reached for localhost:11211 (0.001 seconds left)
down_retry_delay not reached for localhost:11211 (0.001 seconds left)
down_retry_delay not reached for localhost:11211 (0.001 seconds left)
down_retry_delay not reached for localhost:11211 (0.001 seconds left)
[2012-03-20 15:08:28] ERROR NoMethodError: You have a nil object when you didn't expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.each
    /usr/local/lib/ruby/gems/1.9.1/gems/rack-1.3.6/lib/rack/handler/webrick.rb:71:in `service'
    /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
    /usr/local/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
    /usr/local/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'
cache: [GET /assets/kanga_custom/search_merchant.js?body=1] miss, store
Dalli::Server#connect localhost:11211
localhost:11211 failed (count: 3)
localhost:11211 is still down (for 2.030 seconds now)

and

root@rao-desktop:~/Aptana Studio 3 Workspace/Kanga# irb
irb(main):001:0> require 'dalli'
=> true
irb(main):002:0> dc = Dalli::Client.new('localhost:11211')
=> #<Dalli::Client:0x9f89338 @servers="localhost:11211", @options={:expires_in=>0}, @ring=nil>
irb(main):003:0> dc.set('abc', 123)
I, [2012-03-20T15:04:48.093716 #2419] INFO -- : localhost:11211 failed (count: 0)
Dalli::RingError: No server available
    from /usr/local/lib/ruby/gems/1.9.1/gems/dalli-1.1.5/lib/dalli/ring.rb:45:in `server_for_key'
    from /usr/local/lib/ruby/gems/1.9.1/gems/dalli-1.1.5/lib/dalli/client.rb:263:in `perform'
    from /usr/local/lib/ruby/gems/1.9.1/gems/dalli-1.1.5/lib/dalli/client.rb:139:in `set'
    from (irb):3
    from /usr/local/bin/irb:12:in `<main>'
irb(main):004:0>

Solution:-

Try 127.0.0.1 instead of localhost. in delli gem configuration

Ruby slice big array into equal parts

2012-03-19T02:30:00.001-07:00

By using each_slice we can convert single dimension array in to multi dimention array  foo.each_slice(3).to_a #=> [["1", "2", "3"], ["4", "5", "6"], ["7", "8", "9"], ["10"]]

Mobile app implementation

2012-03-12T22:43:00.000-07:00

create an android app by phonegap

http://mobile.tutsplus.com/tutorials/phonegap/creating-an-android-hello-world-application-with-phonegap/

rhoconnect for data synchronization

http://docs.rhomobile.com/rhoconnect/command-line

phonegap home page

http://phonegap.com

rhomobile impotent doc

http://docs.rhomobile.com/rhoconnect/install#rhoconnect-gem-for-linux-and-non-rhostudio

http://docs.rhomobile.com/rhodes/install#rhodes-gem-for-linux-and-non-rhostudio

https://app.rhohub.com/

buld phonegap buld

https://build.phonegap.com/apps

phonegap starting tutorial

http://phonegap.com/start

phonegap docs api

http://docs.phonegap.com/en/1.5.0/index.html

rails3 assets precompile command

2012-03-11T22:26:00.001-07:00

Rails production server assets precompile command debugging way

RAILS_ENV=production bundle exec rake assets:precompile --trace

close current browser tab

2012-03-06T05:38:00.001-08:00

I used the script

function closeWindow(){
window.open('','_self','');
window.close();
}

</script>

this works well with IE (it overrides prompt) and chrome but is not
working with Firefox as by default Firefox don't allow to close tab
using JavaScript
It is needed to follow these steps in Firefox
1. Go to address bar and type about:config
2. Go to parameter dom.allow_scripts_to_close_windows
3. Set its value as true

Rails opensource projects for contributing rails developers

2012-03-01T10:37:00.001-08:00

https://github.com/popular/forked
https://rubyforge.org/account/login.php
http://www.redmine.org/login
http://www.opensourcerails.com/
https://github.com/wycats/merb-core/tree
http://rubygame.org/
http://www.thepeoplesfeed.com/
http://raa.ruby-lang.org/
http://ironruby.net/
http://datamapper.org/
http://www.webresourcesdepot.com/23-amazing-and-open-source-ruby-on-rails-applications/

Rails zip_code validations with prefix zero issue

2012-02-28T21:22:00.000-08:00

rails if we make zip_code as integer value in database it will not gives
the zip_code validations when we give zip_code as 01234 it takes as 1234
like all prefix zeros

solution:-

we have to to make zip_code as string then it will validates zip_code
properly to all zip_codes like 01234

Rails action catching with parameters values

2012-02-28T01:49:00.001-08:00

http://cobaltedge.com/rails-action-caching-with-query-parameters

Ruby on Rails all installations in ubuntu

2011-12-29T19:19:00.001-08:00

Ruby on Rails all installations in ubuntu

####################################################
#                                                                                       #
#      https://help.ubuntu.com/community/RubyOnRails        #
#                                                                                       #
####################################################

PDFTron SDK for ruby Sample code

2011-12-04T23:55:00.001-08:00

The sample code for PDFTron is giver separate for all languages

http://www.pdftron.com/pdfnet/samplecode.html

Click on ruby link in each topic for ruby code.

issue while installing rails_admin gem in ruby on rails

2011-11-24T03:01:00.001-08:00

if we get the error while installing rails_admin for the error
lib/rails_admin/config/fields/types.rb:11:in `load': Unsupported field datatype: binary (RuntimeError)
we have to follow below code in config/initializers/rails_admin.rb

since I don't display the binary field I put this monkey patch in my initializer:

module RailsAdmin   module Config     module Fields       module Types         def self.load(type)           return @@registry[:text] if (type.to_sym == :binary)           @@registry[type.to_sym] or raise "Unsupported field datatype: #{type}"         end       end     end   end end

Admin Interfaces for Rails Apps: RailsAdmin vs ActiveAdmin

2011-11-24T01:01:00.001-08:00

The complete article is on

http://batsov.com/articles/2011/11/20/admin-interfaces-for-rails-apps-railsadmin-vs-activeadmin/

What's the difference between "include" and "require" in Ruby?

2011-11-15T04:20:00.001-08:00

The include and require methods do very different things.

The require method does what include does in most other programming languages: run another file. It also tracks what you've required in the past and won't require the same file twice. To run another file without this added functionality, you can use the load method.

The include method takes all the methods from another module and includes them into the current module. This is a language-level thing as opposed to a file-level thing as with require. The include method is the primary way to "extend" classes with other modules (usually referred to as mix-ins). For example, if your class defines the method "each", you can include the mixin module Enumerable and it can act as a collection. This can be confusing as the include verb is used very differently in other languages.