Add Swap memory to ec2 micro instance.

Remember one thing If ec2 instance memory is 1 GB then add 512 MB swap. It should be half of the instance memory.

To add this extra space to your instance you type:

sudo /bin/dd if=/dev/zero of=/var/swap.1 bs=1M count=1024
sudo /sbin/mkswap /var/swap.1
sudo chmod 600 /var/swap.1
sudo /sbin/swapon /var/swap.1

If you need more than 1024 then change that to something higher.

To enable it by default after reboot, add this line to /etc/fstab:

/var/swap.1   swap    swap    defaults        0   0

Set up mongodb and create user

$> sudo apt-get install -y mongodb
$> mongo
$> use admin

Please note: only change user and password not change to role and db

$> db.createUser({ user: "admin", pwd: "pwd@123", roles: [{ role: "userAdminAnyDatabase", db: "admin" }] })
To check user auth

$> db.auth("admin", "hate2wait@123")
$> 1

create normal user

$> use db_production
$> db.createUser({ user: "myname", pwd: "anypassword", roles: [{ role: "dbOwner", db: "db_production" }] })
$> db.auth("myname", "anypassword")
$>

$> sudo nano /etc/mongodb.conf
# Turn on/off security.  Off is currently the default
#noauth = true

auth = true

Uncomment auth = true
ctrl + x

Change Id to uuid in rails postgresql

Before run this command if you have migration file in migrate folder please take backup all migration file then run this command and migrate it will work.

rails g migration enable_uuid_extension

endclass EnableUuidExtension < ActiveRecord::Migration
  def change
     enable_extension "uuid-ossp"
    enable_extension "pgcrypto"  
   end 
end

MySql command

mysql                         mysql_config_editor        mysqldumpslow              mysqlprocgrep              mysqlserverclone
mysqladmin                 mysqld                     mysql_embedded             mysqlpump                  mysqlserverinfo
mysqlanalyze               mysqldbcompare             mysqlfailover              mysqlrepair                mysqlshow
mysqlauditadmin            mysqldbcopy                mysqlfrm                   mysqlreplicate             mysqlslap
mysqlauditgrep             mysqldbexport              mysqlgrants                mysqlreport                mysqlslavetrx
mysqlbinlog                mysqldbimport              mysqlimport                mysqlrpladmin              mysql_ssl_rsa_setup
mysqlbinlogmove            mysqldiff                  mysqlindexcheck            mysqlrplcheck              mysql_tzinfo_to_sql
mysqlbinlogpurge           mysqldiskusage             mysql_install_db           mysqlrplms                 mysqluc
mysqlbinlogrotate          mysqld_multi               mysqlmetagrep              mysqlrplshow               mysql_upgrade
mysqlcheck                 mysqld_safe                mysqloptimize              mysqlrplsync               mysqluserclone
mysql_config               mysqldump                  mysql_plugin               mysql_secure_installation  mysql-workbench

Create user in mysql 

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';

GRANT ALL ON my_db.* TO 'username'@'localhost';

FLUSH PRIVILEGES;

Upload image using ajax request in rails

          <%=  file_field_tag :customer_profile, id: "customer_profile"  %>           

          var formData = new FormData();
          custProfile  =$("#customer_profile")[0].files[0]
          formData.append("device_img", custProfile);
          $.ajax({
          url: "<%=  upload_image_customer_path(id: params[:id]) %>",
          type: 'POST',
          dataType: 'json',
          data: formData,
          contentType: false,
          processData: false,
          cache : false,
          success: function(data){
            if(data["msg"] == true){
              alert(success)
             }
            },
           error: function(data){
             console.log(data); 
            }
          });

Image convert in base64 in rails

require "base64"

file_url = "https://s3.ap-south-1.amazonaws.com/on-store-billing/uploads/insurance/servify_device_image/58/1__2_.jpeg"

encoded_string = Base64.encode64(open(file_url) { |io| io.read })

decode_img= Base64.decode64(encoded_string)

below given method write/create image with name image.png in directory

File.open(‘image.png’, ‘wb’) { |f| f.write(decode_img) }