diff --git a/devops-service/app/api2/handlers/provider.rb b/devops-service/app/api2/handlers/provider.rb
index 274e840..a054f2c 100644
--- a/devops-service/app/api2/handlers/provider.rb
+++ b/devops-service/app/api2/handlers/provider.rb
@@ -17,7 +17,7 @@ module Devops
         end
 
         def accounts provider
-          ::Provider::ProviderFactory.get(provider).accounts
+          ::Provider::ProviderFactory.get_accounts_factory(provider).accounts
         end
 
         def account_fields provider
@@ -25,8 +25,8 @@ module Devops
         end
 
         def add_account provider
-          account = ::Provider::ProviderFactory.get(provider).create_account(parser.account)
-          key = Devops::Db.connector.key account.ssh_key
+          account = ::Provider::ProviderFactory.get_accounts_factory(provider).create_account(parser.account)
+          account.validate_fields!
           Devops::Db.connector.provider_accounts_insert(account)
           ::Provider::ProviderFactory.add_account(provider, account)
           account.to_hash
@@ -35,6 +35,7 @@ module Devops
         def delete_account name, provider
           account = Devops::Db.connector.provider_accounts_show(name)
           Devops::Db.connector.provider_accounts_delete(name)
+          ::Provider::ProviderFactory.delete_account(provider, account)
           account.to_hash
         end
 
diff --git a/devops-service/app/api2/helpers/version_2.rb b/devops-service/app/api2/helpers/version_2.rb
index 08a538b..2e4ce94 100644
--- a/devops-service/app/api2/helpers/version_2.rb
+++ b/devops-service/app/api2/helpers/version_2.rb
@@ -30,7 +30,7 @@ module Devops
 
       def check_provider provider
         list = ::Provider::ProviderFactory.providers
-        halt_response("Invalid provider '#{provider}', available providers: '#{list.join("', '")}'", 404) unless list.include?(provider)
+        halt_response("Invalid provider '#{provider}', available providers: '#{list.join("', '")}'", 400) unless list.include?(provider)
       end
 
       # Save information about requests with methods POST, PUT, DELETE
diff --git a/devops-service/app/api2/routes/v2.0.rb b/devops-service/app/api2/routes/v2.0.rb
index 4a220d9..3645afc 100644
--- a/devops-service/app/api2/routes/v2.0.rb
+++ b/devops-service/app/api2/routes/v2.0.rb
@@ -61,13 +61,23 @@ module Devops
         DevopsLogger.logger = @@logger
         begin
           res = super(env)
-        rescue DevopsError => e
+        rescue ::Devops::Exception::DevopsError => e
+          return [e.code, {}, e.message]
+        rescue InvalidRecord => e
           return [e.code, {}, e.message]
         end
         @@access_logger.info(env["REQUEST_METHOD"] + " " + env["REQUEST_URI"] + " - from #{env["HTTP_USER_AGENT"]} (#{env["REMOTE_USER"]}) / #{res[0]}")
         res
       end
 
+      def handle_exception!(boom)
+        if boom.is_a?(::Devops::Exception::DevopsError)
+          boom.http_response
+        else
+          super(boom)
+        end
+      end
+
       error Devops::ValidationError do
         e = env["sinatra.error"]
         #logger.warn e.message
@@ -92,12 +102,14 @@ module Devops
         halt_response(e.message, 404)
       end
 
+=begin
       error InvalidRecord do
         e = env["sinatra.error"]
         logger.warn e.message
         logger.warn "Request body: #{request.body.read}"
         halt_response(e.message, 400)
       end
+=end
 
       error InvalidCommand do
         e = env["sinatra.error"]
diff --git a/devops-service/app/devops-api2.rb b/devops-service/app/devops-api2.rb
index 4eb8832..5e650de 100644
--- a/devops-service/app/devops-api2.rb
+++ b/devops-service/app/devops-api2.rb
@@ -78,7 +78,7 @@ module Devops
         Devops::Api2.register r
       end
       Routes.route "/v2.0", Devops::Api2
-      Devops::Api2.routes_list
+      #Devops::Api2.routes_list
     end
 
     private
diff --git a/devops-service/db/mongo/models/mongo_model.rb b/devops-service/db/mongo/models/mongo_model.rb
index 60e46b7..3721a5c 100644
--- a/devops-service/db/mongo/models/mongo_model.rb
+++ b/devops-service/db/mongo/models/mongo_model.rb
@@ -66,6 +66,21 @@ module Devops
         end
       end
 
+      def validate_fields!
+        result = []
+        self.class.field_validators.each do |field, validation_method|
+          begin
+            self.send(validation_method)
+          rescue InvalidRecord => e
+            result << {key: field, message: e.message}
+          end
+        end
+        unless result.empty?
+          raise InvalidRecord.new(error_data: result)
+        end
+        true
+      end
+
       def build_error_message(message)
         # overrided in descendants
         message
@@ -123,17 +138,16 @@ module Devops
       end
 
       @validators = []
-#      @field_validators = []
+      @field_validators = {}
       class << self
 
         attr_accessor :validators
-#        attr_accessor :field_validators
+        attr_accessor :field_validators
 
         def inherited(subclass)
           subclass.validators = []
           subclass.validators += self.validators
-#          subclass.field_validators = []
-#          subclass.field_validators += self.field_validators
+          subclass.field_validators = self.field_validators.clone
         end
 
         # all exceptions are handled in @validate! method
@@ -146,11 +160,13 @@ module Devops
         # validate field value
         # if method validate! returns false, then stop validation without error
         def set_field_validators field, *validators
-          define_method("validate_" + field.to_s + "!") do
+          method_name = "validate_" + field.to_s + "!"
+          define_method(method_name) do
             validators.each do |validator|
               break unless validator.new(self, send(field)).validate!
             end
           end
+          self.field_validators[field] = method_name
         end
 
         # private class methods
diff --git a/devops-service/db/mongo/models/provider_accounts/ec2_provider_account.rb b/devops-service/db/mongo/models/provider_accounts/ec2_provider_account.rb
index 85ee83a..3f2fb41 100644
--- a/devops-service/db/mongo/models/provider_accounts/ec2_provider_account.rb
+++ b/devops-service/db/mongo/models/provider_accounts/ec2_provider_account.rb
@@ -6,6 +6,13 @@ module Devops
 
       attr_accessor :access_key_id, :availability_zone, :secret_access_key
 
+      set_field_validators :access_key_id, ::Validators::FieldValidator::NotNil,
+                                           ::Validators::FieldValidator::FieldType::String,
+                                           ::Validators::FieldValidator::NotEmpty
+
+      set_field_validators :secret_access_key, ::Validators::FieldValidator::NotNil,
+                                               ::Validators::FieldValidator::FieldType::String,
+                                               ::Validators::FieldValidator::NotEmpty
       def initialize a={}
         super(a)
         self.provider = Provider::Ec2::PROVIDER
diff --git a/devops-service/db/mongo/models/provider_accounts/provider_account.rb b/devops-service/db/mongo/models/provider_accounts/provider_account.rb
index 2bfed36..3a6fb59 100644
--- a/devops-service/db/mongo/models/provider_accounts/provider_account.rb
+++ b/devops-service/db/mongo/models/provider_accounts/provider_account.rb
@@ -9,6 +9,21 @@ module Devops
 
       attr_accessor :account_name, :description, :ssh_key
 
+      set_field_validators :account_name, ::Validators::FieldValidator::NotNil,
+                                          ::Validators::FieldValidator::FieldType::String,
+                                          ::Validators::FieldValidator::NotEmpty,
+                                          ::Validators::FieldValidator::Name
+
+      set_field_validators :description, ::Validators::FieldValidator::Nil,
+                                         ::Validators::FieldValidator::FieldType::String,
+                                         ::Validators::FieldValidator::NotEmpty,
+                                         ::Validators::FieldValidator::Description
+
+      set_field_validators :ssh_key, ::Validators::FieldValidator::NotNil,
+                                     ::Validators::FieldValidator::FieldType::String,
+                                     ::Validators::FieldValidator::NotEmpty,
+                                     ::Validators::FieldValidator::SshKey
+
       ACCOUNT_FIELDS = {
         account_name: "Account name (id)",
         description: "Account description",
diff --git a/devops-service/db/validators/field_validators/description.rb b/devops-service/db/validators/field_validators/description.rb
new file mode 100644
index 0000000..c414e3a
--- /dev/null
+++ b/devops-service/db/validators/field_validators/description.rb
@@ -0,0 +1,17 @@
+require_relative "base"
+module Validators
+  module FieldValidator
+    class Description < Base
+
+      MAX_LEN = 500
+
+      def valid?
+        @value.size <= 500
+      end
+
+      def message
+        "Invalid value '#{@value}': it should be less or equals then #{MAX_LEN} symbols"
+      end
+    end
+  end
+end
diff --git a/devops-service/db/validators/field_validators/name.rb b/devops-service/db/validators/field_validators/name.rb
index 1319d85..4603934 100644
--- a/devops-service/db/validators/field_validators/name.rb
+++ b/devops-service/db/validators/field_validators/name.rb
@@ -11,7 +11,7 @@ module Validators
       end
 
       def message
-        "Invalid value '#{@value}': it should contains symbols 'a-zA-Z0-9_' and length should be more then 1 and less or equals then #{MAX_NAME_LEN}"
+        "Invalid value '#{@value}': it should contains symbols 'a-zA-Z0-9_' and length should be more then 1 and less or equals then #{MAX_NAME_LEN} symbols"
       end
     end
   end
diff --git a/devops-service/db/validators/field_validators/ssh_key.rb b/devops-service/db/validators/field_validators/ssh_key.rb
new file mode 100644
index 0000000..fce76e3
--- /dev/null
+++ b/devops-service/db/validators/field_validators/ssh_key.rb
@@ -0,0 +1,20 @@
+require_relative "base"
+module Validators
+  module FieldValidator
+    class SshKey < Base
+
+      MAX_LEN = 500
+
+      def valid?
+        Devops::Db.connector.key @value
+        true
+      rescue RecordNotFound
+        false
+      end
+
+      def message
+        "Invalid value '#{@value}': ssh key '#{@value}' not found"
+      end
+    end
+  end
+end
diff --git a/devops-service/exceptions/devops_error.rb b/devops-service/exceptions/devops_error.rb
index 996ec04..fdcb6a2 100644
--- a/devops-service/exceptions/devops_error.rb
+++ b/devops-service/exceptions/devops_error.rb
@@ -1,12 +1,25 @@
+require "json"
 module Devops
   module Exception
 
     class DevopsError < StandardError
 
-      def code
+      def http_status
         500
       end
 
+      def http_response
+        [self.http_status, self.http_headers, self.http_body]
+      end
+
+      def http_body
+        JSON.pretty_generate(message: self.message)
+      end
+
+      def http_headers
+        {"Content-Type" => "application/json"}
+      end
+
     end
 
   end
diff --git a/devops-service/exceptions/invalid_record.rb b/devops-service/exceptions/invalid_record.rb
index 5ca7cb1..48d3750 100644
--- a/devops-service/exceptions/invalid_record.rb
+++ b/devops-service/exceptions/invalid_record.rb
@@ -1,3 +1,23 @@
-class InvalidRecord < StandardError
+require_relative "devops_error"
+class InvalidRecord < ::Devops::Exception::DevopsError
 
+  def initialize msg
+    if msg.is_a?(String)
+      super(msg)
+    else
+      @object = msg
+    end
+  end
+
+  def http_status
+    400
+  end
+
+  def http_body
+    if @object.nil?
+      super
+    else
+      JSON.pretty_generate(@object)
+    end
+  end
 end
diff --git a/devops-service/providers/accounts_factory.rb b/devops-service/providers/accounts_factory.rb
index c956b14..7f212e9 100644
--- a/devops-service/providers/accounts_factory.rb
+++ b/devops-service/providers/accounts_factory.rb
@@ -14,8 +14,20 @@ module Provider
       @connections[name] = conn
     end
 
+    def delete_connection name
+      @connections.delete(name)
+    end
+
     def create_connection_from_account config, account
     end
+
+    def accounts
+      Devops::Db.connector.provider_accounts(provider_name)
+    end
+
+    def create_account hash
+      raise "override me"
+    end
   end
 end
 
diff --git a/devops-service/providers/base_provider.rb b/devops-service/providers/base_provider.rb
index a7d27dc..bf9ef34 100644
--- a/devops-service/providers/base_provider.rb
+++ b/devops-service/providers/base_provider.rb
@@ -6,14 +6,6 @@ module Provider
 
     attr_accessor :ssh_key, :certificate_path, :connection_options, :run_list
 
-    def accounts
-      Devops::Db.connector.provider_accounts(self.name)
-    end
-
-    def create_account hash
-      raise "override me"
-    end
-
     def create_default_chef_node_name s
       "#{self.ssh_key}-#{s.project}-#{s.deploy_env}-#{Time.now.to_i}"
     end
diff --git a/devops-service/providers/ec2.rb b/devops-service/providers/ec2.rb
index 40fb10b..73aff74 100644
--- a/devops-service/providers/ec2.rb
+++ b/devops-service/providers/ec2.rb
@@ -35,10 +35,6 @@ module Provider
       super and !(empty_param?(o[:aws_access_key_id]) or empty_param?(o[:aws_secret_access_key]))
     end
 
-    def create_account hash
-      Devops::Model::Ec2ProviderAccount.new(hash)
-    end
-
     def name
       PROVIDER
     end
diff --git a/devops-service/providers/ec2_accounts_factory.rb b/devops-service/providers/ec2_accounts_factory.rb
index 88198e2..58eb3a8 100644
--- a/devops-service/providers/ec2_accounts_factory.rb
+++ b/devops-service/providers/ec2_accounts_factory.rb
@@ -4,13 +4,17 @@ module Provider
 
     def init config
       @connections = {}
-      Devops::Db.connector.provider_accounts(Ec2::PROVIDER).each do |account|
+      accounts.each do |account|
         create_connection_from_account(config, account)
         puts "\tFound ec2 account '#{account.account_name}'"
       end
       ProviderFactory.add_provider Ec2::PROVIDER unless @connections.empty?
     end
 
+    def provider_name
+      Ec2::PROVIDER
+    end
+
     def create_connection_from_account config, account
        options = {
         aws_ssh_key: account.ssh_key,
@@ -25,5 +29,9 @@ module Provider
       add_connection(account.account_name, Ec2.new(options))
     end
 
+    def create_account hash
+      Devops::Model::Ec2ProviderAccount.new(hash)
+    end
+
   end
 end
diff --git a/devops-service/providers/provider_factory.rb b/devops-service/providers/provider_factory.rb
index 3bb8610..921cceb 100644
--- a/devops-service/providers/provider_factory.rb
+++ b/devops-service/providers/provider_factory.rb
@@ -50,6 +50,7 @@ module Provider
           next
         end
       end
+      puts "Available providers: #{@@available_providers}"
     end
 
     def self.add_account provider, account
@@ -58,6 +59,12 @@ module Provider
       DevopsLogger.logger.info("Added #{provider} account '#{account.account_name}'")
     end
 
+    def self.delete_account provider, account
+      factory = @@providers_with_accounts_factories[provider]
+      factory.delete_connection(account.account_name)
+      DevopsLogger.logger.info("Removed #{provider} account '#{account.account_name}'")
+    end
+
     def self.require_all
       ["ec2", "openstack", "static"].each do |provider|
         begin
@@ -69,6 +76,10 @@ module Provider
       end
     end
 
+    def self.get_accounts_factory provider
+      @@providers_with_accounts_factories[provider]
+    end
+
     def self.get_account_class provider
       case(provider)
       when ::Provider::Static::PROVIDER