Backup your system databases using Ruby backup gem

Install RVM (Or Rbenv) to manage your Ruby versions

 $ gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 7D2BAF1CF37B13E2069D6956105BD0E739499BDB
 $ curl -sSL https://get.rvm.io | bash 

Restart Terminal and type rvm -v

 $ rvm install 2.5
 $ rvm gemset create backup
 $ rvm gemset use backup
 $ gem install backup
 $ backup generate:model --trigger project_2_backup --archives --storages='s3' --compressor='gzip' --notifiers='mail' 
 Generated configuration file: '/home/ubuntu/Backup/config.rb'.
 Generated model file: '/home/ubuntu/Backup/models/project_2_backup.rb'.
 Usage:
   backup generate:model --trigger=TRIGGER
 Options:
   --trigger=TRIGGER
   [--config-path=CONFIG_PATH]  # Path to your Backup configuration directory
   [--databases=DATABASES]      # (mongodb, mysql, postgresql, redis, riak)
   [--storages=STORAGES]        # (cloudfiles, dropbox, ftp, local, ninefold, rsync, s3, scp, sftp)
   [--syncers=SYNCERS]          # (cloud_files, rsync_local, rsync_pull, rsync_push, s3)
   [--encryptors=ENCRYPTORS]    # (gpg, openssl)
   [--compressors=COMPRESSORS]  # (bzip2, gzip, lzma, pbzip2)
   [--notifiers=NOTIFIERS]      # (campfire, hipchat, mail, presently, prowl, twitter)
   [--archives]
   [--splitter]                 # use `--no-splitter` to disable
                               # Default: true 

Sample Model File

Add the following conf in Backup/models/project_2_backup.rb:

Example for mongodb

 database MongoDB do |db|
     db.name               = "db_name"
     db.username           = "db_username"
     db.password           = "db_pswd"
     db.host               = "localhost"
     db.port               = 27017 
     db.ipv6               = false
     #db.only_collections   = ["only", "these", "collections"]
     db.additional_options = ['--authenticationDatabase=admin']
     db.lock               = false
     db.oplog              = false
   end
   ## 
   # Amazon Simple Storage Service [Storage]
   #
   store_with S3 do |s3|
     # AWS Credentials
     s3.access_key_id     = "YOUR_ACCESS_KEY"
     s3.secret_access_key = "YOUR_SECRET_KEY"
     # Or, to use a IAM Profile:
     # s3.use_iam_profile = true
     s3.region            = "ap-southeast-2" 
     s3.bucket            = "bucket_name"
     s3.path              = "bucket_name_path"
     s3.keep              = 12
     # s3.keep              = Time.now - 2592000 # Remove all backups older than 1 month.
   end 

 # Notification mail infos
 notify_by Mail do |mail|
     mail.on_success           = true
     mail.on_warning           = true
     mail.on_failure           = true
     mail.from                 = "_____@gmail.com"
     mail.to                   = "____@___.com"
     mail.cc                   = "______@_____.com, _____@______.com"
     #mail.bcc                  = "bcc@email.com"
     #mail.reply_to             = "reply_to@email.com" 
     mail.address              = "smtp.gmail.com"
     mail.port                 = 587
     mail.domain               = "domain_name"
     mail.user_name            = "email_username"
     mail.password             = "email_password"
     mail.authentication       = "plain"
     mail.encryption           = :starttls
 end 

Once you’ve setup your configuration, check your work with:

$ backup check

If there are no errors, the check should report:

[2019/03/28 10:02:26][info] Configuration Check Succeeded.

Perform Backup:

$ backup perform --trigger project_2_backup

The Keep Option

keep a specified number of backups in storage. After each backup is performed, it will remove older backup package files based on the keep setting.

keep as a Number

If a number has been specified and once the keep limit has been reached, the oldest backup will be removed.

Note that if keep is set to 5, then the 6th backup will be transferred and stored, before the oldest is removed. So be sure you have space available for keep + 1 backups

keep as Time

When a Time object is set to keep it will keep backups until that time. Everything older than the set time will be removed.

Rails 5.2.0 API Only application with latest Ruby 2.5.1

Check for the new ruby and rails versions
https://www.ruby-lang.org/en/downloads/
https://rubygems.org/gems/rails/versions

Here we are going to install Ruby – 2.5.1 & Rails – 5.2.0 (API only application)

Get rbenv into action
If you are not installed rbenv, you can install it from here:
https://github.com/rbenv/rbenv
After the installation make sure that, your $PATH has included rbenv/shims path. Else rbenv will not work.

1. $ rbenv install --list # Gets the list of ruby versions available

$ rbenv install 2.5.1

ruby-build: definition not found: 2.5.1

The following versions contain `2.5.1' in the name:
  rbx-2.5.1

See all available versions with `rbenv install --list'.

If the version you need is missing, try upgrading ruby-build:

  brew update && brew upgrade ruby-build

Oops..!

rbenv cannot find the version: 2.5.1

Upgrade ruby-build

Mac OSX:

$ brew upgrade ruby-build --HEAD

Now install ruby 2.5.1

$ rbenv install 2.5.1

Create a new gemset:

Rbenv gemset is a separate script and not coming with rbenv. If you are not installed this, you can install it from here:
https://github.com/jf/rbenv-gemset

$ rbenv gemset create 2.5.1 demo-app
That set up a directory for you in ~/.rbenv/versions/2.5.1/gemsets/demo-app

Set the ruby version to the newest

$ rbenv local 2.5.1

$ rbenv version
=> 2.5.1

    Activate New Gemset


For activating a gemset we need to create a .rbenv-gemsets file in the current directory.

$ touch .rbenv-gemsets
$ echo demo-app > .rbenv-gemsets

Check active gemset:

$ rbenv gemset active

Install Rails 5.2.0 API only Application

$ gem install rails -v '5.2.0'

$ rails -v
Rails 5.2.0

Later we can delete this .rbenv-gemsets file and add a new file named ‘.ruby-gemset’ in the rails project directory. I cannot find any other option for doing this. If anyone know more about this, please give a comment. I appreciate that.

Create a New Rails app

$ rails new demo-app  --api -T # API only skip the testing framework altogether

For Full Rails:

$ rails new demo-app -T -d postgresql # skip the testing framework altogether, uses Postgres Database

-T to exclude Minitest – the default testing framework if you are planning to use RSpec to test your API.

Rspec test framework:
https://github.com/rspec/rspec-rails

You can use the following with Rspec.
Shoulda Matchers:
Collection of testing matchers extracted from Shoulda (http://matchers.shoulda.io)
https://github.com/thoughtbot/shoulda-matchers

Database Cleaner:
Strategies for cleaning databases in Ruby. Can be used to ensure a clean state for testing
https://github.com/DatabaseCleaner/database_cleaner

Faker:
A library for generating fake data such as names, addresses, and phone numbers.
https://github.com/stympy/faker

use option: –no-rdoc –no-ri # skips the documentation

Remove Rbenv Gemset and add Ruby gems file

$ rm .rbenv-gemsets

$ cd demo-app
$ touch .ruby-gemset
$ echo demo-app > .ruby-gemset
$ rails s
=> Booting Puma
=> Rails 5.2.0 application starting in development
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.11.4 (ruby 2.5.1-p57), codename: Love Song
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop

Goto http://localhost:3000/

rails-5.2.api-application

Done! Lets go…

#Rails 4.2: How to create a full URL with given host and port

Basically if you need to generate url based on the current url during a request OR you can create your own Urls by using Rails ‘ActionDispatch::Integration::Session‘ class.

Rails creates an object ‘app’. It is and action dispatch session object.

You can make use of that object for creating your own URLs like:

> app.root_url(:port => 20)  => "http://www.example.com:20/"

> app.root_url(:port => 20, :host => 'www.bing.com')
 => "http://www.bing.com:20/"

During a request you can use like this:

 > request.url(:port => 20)

How to send Basic Authentication (BA) credentials in ruby on rails

HTTP Basic authentication is a simple authentication scheme in which user authentication is done by a username and password eliminating the needs of cookies, sessions and login pages. It is base64 encoded.

Rails provides a method for this type of authentication: authenticate_with_http_basic

This method can be used as follows:

authenticate_with_http_basic do |username, password|
  ——
end

Inside the block you can access the username and password.

But how to send a request with basic auth in rails ?

This is really tricky and I didn’t find any documentation for this. Here I am describing how to send a request with basic auth.

1. Use Faraday library (Faraday is an HTTP client lib)
https://github.com/lostisland/faraday

Create a connection:

connection = Faraday.new(:url => HOST) do |faraday|
      faraday.request  :url_encoded             # form-encode POST params
      faraday.response :logger                  # log requests to STDOUT
      faraday.adapter  Faraday.default_adapter  # make requests with Net::HTTP
      faraday.basic_auth(USERNAME, PASSWORD)
end

parameters = params[‘user’].permit!.to_h

response = connection.get do |req|
      req.url(params[:url])
      req.headers['Content-Type'] = 'application/json'
      req.params.merge!(parameters)
end

response = connection.post do |req|
        req.url(params[:url])
        req.headers['Content-Type'] = 'application/json'
        req.body = parameters
end

render json: response.body

Here,

HOST = 'http://lvh.me:3002'
USERNAME = 'EdcddzrbmET55016'
PASSWORD = 'UXBJnS309S49st3rHqmH5934'
params['url'] = '/users/profile'

We can use Faraday’s (‘faraday.basic_auth’) basic auth method to reach out our solution.

If you are getting any error like follows in post request

NoMethodError (undefined method `bytesize' for {}:ActiveSupport::HashWithIndifferentAccess):

Don’t forget to convert the ruby hash ‘parameters’ to json by calling ‘to_json’ upon it.

        req.body = parameters.to_json 

In Other way you can use something like this to generate the basic auth header

request.env['HTTP_AUTHORIZATION'] = ActionController::HttpAuthentication::Basic.encode_credentials(USERNAME, PASSWORD)

How to use Ruby Rest Client:

require 'rest_client'

headers = {
  :authorization => 'Basic FytxhZGKpbjpvcGVuIHNlc2FtHUHU'
}

response = RestClient.get 'https://yourdomain.com/api/users.json?activityId=02ddf868-6484-440f-8c39-c7d4fb4e7b33', headers
puts response

Rbenv: Start with new ruby and rails versions

Check for the new ruby and rails versions
https://www.ruby-lang.org/en/downloads/
https://rubygems.org/gems/rails/versions

Here we are going to install Ruby – 2.4.1 & Rails – 5.1.3

Get rbenv into action
If you are not installed rbenv, you can install it from here:
https://github.com/rbenv/rbenv
After the installation make sure that, your $PATH has included rbenv/shims path. Else rbenv will not work.

1. $ rbenv install --list # Gets the list of ruby versions available

$ rbenv install 2.4.1

ruby-build: definition not found: 2.4.1

The following versions contain `2.4.1' in the name:
  rbx-2.4.1

See all available versions with `rbenv install --list'.

If the version you need is missing, try upgrading ruby-build:

  brew update && brew upgrade ruby-build

Oops..!

rbenv cannot find the version: 2.4.1

Upgrade ruby-build

Mac OSX:

$ brew upgrade ruby-build --HEAD

Now install ruby 2.4.1

$ rbenv install 2.4.1

Create a new gemset:

Rbenv gemset is a separate script and not coming with rbenv. If you are not installed this, you can install it from here:
https://github.com/jf/rbenv-gemset

$ rbenv gemset create 2.4.1 demo-app
That set up a directory for you in ~/.rbenv/versions/2.4.1/gemsets/demo-app

Set the ruby version to the newest

$ rbenv local 2.4.1

$ rbenv version
=> 2.4.1

    Activate New Gemset


For activating a gemset we need to create a .rbenv-gemsets file in the current directory.

$ touch .rbenv-gemsets
$ echo demo-app > .rbenv-gemsets

Check active gemset:

$ rbenv gemset active

Install Rails 5.1.3

$ gem install rails -v '5.1.3'
$ gem install --no-rdoc --no-ri rails -v '5.1.3' # skips the documentation

Later we can delete this .rbenv-gemsets file and add a new file named ‘.ruby-gemset’ in the rails project directory. I cannot find any other option for doing this. If anyone know more about this, please give a comment. I appreciate that.

Create a New Rails app

$ rails new demo-app

$ rm .rbenv-gemsets

$ cd demo-app
$ touch .ruby-gemset
$ echo demo-app > .ruby-gemset
$ touch .ruby-version
$ echo 2.4.1 > .ruby-version
$ rails s
=> Booting Puma
=> Rails 5.1.3 application starting in development on http://localhost:3000
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.9.1 (ruby 2.4.1-p111), codename: Private Caller
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://0.0.0.0:3000
Use Ctrl-C to stop

Goto http://localhost:3000/

rails-5-new.png

Done! Lets go…

#Rails 4.2 #Ruby2.2 How to find association class and other info from an object and its association name

When I was doing a Rails project, I encountered one situation like: I need the association class of an association object. I have the object and its association name as input. How can I find the association class?

Suppose we have Student class that belongs to a school

class School
  has_many students
end

class Student
  belongs_to :school
end

and suppose so many other relations like this in our project.

So we have

s = Student.last
:school symbol 

I can use

s.school.class and s.school.class.name

But what if the school is blank? The result is ‘NilClass’ From the above code.

Basically for has_many associations now we get the class name as

"ActiveRecord::Associations::CollectionProxy"

because recently in new rails version a change of the Array of objects as associations to its own ‘CollectionProxy’ collections.

So we can use ‘ActiveRecord::Reflection::ClassMethods’ for finding all the association info.

Note that this Rails module is so useful to find all the association related information.

In the above situation we can use ‘reflect_on_association’ method for finding association reflection info. And it returns ‘ActiveRecord::Reflection’ Object.

http://api.rubyonrails.org/classes/ActiveRecord/Reflection/ClassMethods.html#method-i-reflect_on_association

Check the following code:

> s.class.reflect_on_association(:school)
=> ##}, @scope_lock=#
, @class_name="Topic", @foreign_key="school_id">

Namespaced classes in Ruby

We can write namspaced classes in ruby in two ways.

Normal way we can wrap the class inside a module. Lets say the module name as ‘MyModule’.
And the constants we define inside this module are accessed as follows:


module MyModule
    CONST1 = 1
    class Myclass
       CONST2 = 2
       def name
          "This is my name"
       end

       def const_1
         CONST1
       end

       def const_2
          CONST2
       end
    end
end

p MyModule::Myclass.new.name
p MyModule::Myclass.new.const_1
p MyModule::Myclass.new.const_2

The other way of doing this is the short way of writing the class name with module name and two columns.
As you can see, the const_1 is accessed as prefixing the module name with two columns.

module MyModule
    CONST1 = 1
end

class MyModule::Myclass
    CONST2 = 2
    
    def name
       "This is my name"
    end
    
    def const_1
        MyModule::CONST1        
    end
    
    def const_2
        CONST2
    end
end

p MyModule::Myclass.new.name
p MyModule::Myclass.new.const_1
p MyModule::Myclass.new.const_2

There is an another way of doing this, that may looks strange to most of the people. Nested classes.

class Myclass
  def name
     "This is my name"
  end

  def my_class_2_name
     Myclass2.new.name
  end

  class Myclass2
    def name
       Myclass.new.name
    end
  end
end

> p Myclass.new.name
> "This is my name"
> p Myclass.new.my_class_2_name
> "This is my name"

The two printing works. So what is the use of these nested classes? Hmmm. It is just namespacing the second class and it tells, somehow it relates to first class even though there is no relation between these two classes.

> p Myclass2.new.name
> uninitialized constant Myclass2

We cannot access Myclass2 without specifying the namespace ( Myclass )

> p Myclass::Myclass2.new.name
> "This is my name"