Class: Rbcli::State::RemoteConnectors::DynamoDB

Inherits:
Object
  • Object
show all
Defined in:
lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dynamodb_table, region, aws_access_key_id, aws_secret_access_key, locking: false, lock_timeout: 60) ⇒ DynamoDB

Returns a new instance of DynamoDB.



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 22

def initialize dynamodb_table, region, aws_access_key_id, aws_secret_access_key, locking: false, lock_timeout: 60
	@region = region
	@dynamo_table_name = dynamodb_table
	@item_name = Rbcli::configuration[:scriptname]
	@locking = locking
	@scheduler = nil
	@lock_timeout = lock_timeout
	@exit_code_set = false
	@should_unlock_at_exit = false

	@dynamo_client = Aws::DynamoDB::Client.new(
			region: @region,
			access_key_id: aws_access_key_id,
			secret_access_key: aws_secret_access_key
	)
end

Class Method Details

.save_defaults(aws_access_key_id: nil, aws_secret_access_key: nil) ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 9

def self.save_defaults aws_access_key_id: nil, aws_secret_access_key: nil
	Rbcli::Config::add_categorized_defaults :dynamodb_remote_state, 'Remote State Settings - requires DynamoDB', {
			access_key_id: {
					description: 'AWS Access Key ID -- leave as null to look for AWS credentials on system. See: https://docs.aws.amazon.com/sdk-for-ruby/v3/developer-guide/setup-config.html',
					value: aws_access_key_id
			},
			secret_access_key: {
					description: 'AWS Secret Access Key -- leave as null to look for AWS credentials on system.',
					value: aws_secret_access_key
			}
	}
end

Instance Method Details

#create_table ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 39

def create_table
	# We only need to create the table
	unless table_exists?
		print "Creating DynmoDB Table. Please wait..."
		@dynamo_client.create_table(
				{
						attribute_definitions: [
								{
										attribute_name: "Script Name",
										attribute_type: "S"
								}
						],
						key_schema: [
								{
										attribute_name: "Script Name",
										key_type: "HASH"
								}
						],
						provisioned_throughput: {
								read_capacity_units: 5,
								write_capacity_units: 5,
						},
						table_name: @dynamo_table_name,
				}
		)
		wait_for_table_creation
	end
end

#get_object ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 86

def get_object
	lock_or_wait
	item = @dynamo_client.get_item(
			{
					key: {'Script Name' => @item_name},
					table_name: @dynamo_table_name,
			}
	).item
	item.delete 'Script Name'
	item
end

#lock ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 109

def lock
	@dynamo_client.put_item(
			{
					table_name: @dynamo_table_name,
					item: {
							'Script Name' => "#{@item_name}_lock",
							'locked' => true,
							'locked_until' => (Time.now + @lock_timeout).getutc.strftime('%s'),
							'locked_by' => Digest::SHA2.hexdigest(Mac.addr)
					}
			}
	)
end

#lock_or_wait(recursed = false) ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 145

def lock_or_wait recursed = false
	return true unless @locking
	delay_in_seconds = 2
	lockdata = get_lockdata

	should_claim = false

	# First, we identify if the lock is active
	if lockdata['locked']
		# If the lock is not ours, we have to check the expiration
		if lockdata['locked_by'] != Digest::SHA2.hexdigest(Mac.addr)
			# If the lock is not ours, and it has expired, we claim it
			if lockdata['locked_until'].to_i < Time.now.getutc.to_i
				should_claim = true
				# If the lock data is not ours and has not expired, we wait and try again
			else
				print 'Acquiring lock on DynamoDB. Please wait..' unless recursed
				print '.'
				sleep delay_in_seconds
				lock_or_wait true
			end

			# If the lock is ours, we check the expiry
		else
			# If the lock is ours and is close to expiry or has expired, we refresh it
			if lockdata['locked_until'].to_i < (Time.now - (@lock_timeout / 10)).getutc.to_i
				should_claim = true
				# If the lock is ours and is not near expiry, do nothing
			else
				# Do nothing! But do finish the string that's shown to the user
				puts 'done!' if recursed
			end
		end
	else # If clearly unlocked, we claim it
		should_claim = true
	end


	if should_claim
		# We attempt to get a lock then validate our success
		lock
		# If we succeeded then we set up a scheduler to ensure we keep it
		lockdata = get_lockdata
		if (lockdata['locked_by'] == Digest::SHA2.hexdigest(Mac.addr)) and (lockdata['locked_until'].to_i > Time.now.getutc.to_i)
			# Of course, if the scheduler already exists, we don't bother
			unless @scheduler
				@scheduler ||= Rufus::Scheduler.new
				@scheduler.every "#{@lock_timeout - 2}s" do
					lock
				end
				# We also make sure we release the lock at exit. In case this doesn't happen, the lock will expire on its own
				@should_unlock_at_exit = true
				unless @exit_code_set
					at_exit {unlock if @should_unlock_at_exit}
					@exit_code_set = true
				end
			end
			puts 'done!' if recursed
			# If we failed locking then we need to try the process all over again
		else
			print 'Error: Failed to lock DynamoDB. Retrying...'
			sleep delay_in_seconds
			lock_or_wait true
		end

	end

end

#locked? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 140

def locked?
	lockdata = get_lockdata
	(lockdata['locked']) and (lockdata['locked_until'].to_i > Time.now.getutc.to_i) and (lockdata['locked_by'] != Digest::SHA2.hexdigest(Mac.addr))
end

#object_exists? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 72

def object_exists?
	begin
		item = @dynamo_client.get_item(
				{
						key: {'Script Name' => @item_name},
						table_name: @dynamo_table_name,
				}
		)
		return (!item.item.nil?)
	rescue Aws::DynamoDB::Errors::ResourceNotFoundException
		return false
	end
end

#save_object(datahash) ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 98

def save_object datahash
	raise StandardError "DynamoDB has been locked by another user since the last change. Please try again later." if locked?
	lock_or_wait
	@dynamo_client.put_item(
			{
					table_name: @dynamo_table_name,
					item: datahash.merge({'Script Name' => @item_name})
			}
	)
end

#table_exists? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 68

def table_exists?
	@dynamo_client.list_tables.table_names.to_a.include? @dynamo_table_name
end

#unlock ⇒ Object 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 123

def unlock
	@dynamo_client.put_item(
			{
					table_name: @dynamo_table_name,
					item: {
							'Script Name' => "#{@item_name}_lock",
							'locked' => false,
							'locked_until' => Time.now.getutc.strftime('%s'),
							'locked_by' => false
					}
			}
	)
	@scheduler.shutdown :kill if @scheduler
	@should_unlock_at_exit = false
	@scheduler = nil
end