Class: LambdaWrap::DynamoDbManager

Inherits:
Object
  • Object
show all
Defined in:
lib/lambda_wrap/dynamo_db_manager.rb

Overview

The DynamoDBManager simplifies setting up and destroying a DynamoDB database.

Note: In case an environment specific DynamoDB tablename such as <baseTableName>-production should be used, then it has to be injected directly to the methods since not all environments necessarily need separated databases.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ DynamoDbManager

The constructor does some basic setup

  • Validating basic AWS configuration

  • Creating the underlying client to interact with the AWS SDK.



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# File 'lib/lambda_wrap/dynamo_db_manager.rb', line 17

def initialize()
  AwsSetup.new.validate()
  # AWS dynamodb client

  @client = Aws::DynamoDB::Client.new()
end

Instance Method Details

#delete_database(table_name) ⇒ Object

Deletes a DynamoDB table. It does not wait until the table has been deleted.

Arguments [table_name] The dynamoDB table name to delete.



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# File 'lib/lambda_wrap/dynamo_db_manager.rb', line 85

def delete_database(table_name)
  
  begin
    table_details = @client.describe_table(table_name: table_name).table
    wait_until_table_available(table_name) if (table_details.table_status != 'ACTIVE')
    @client.delete_table({table_name: table_name})
  rescue Aws::DynamoDB::Errors::ResourceNotFoundException
    puts 'Table did not exist. Nothing to delete.'
  end
  
end

#publish_database(table_name, attribute_definitions, key_schema, read_capacity, write_capacity) ⇒ Object

Publishes the database and awaits until it is fully available. If the table already exists, it only adjusts the read/write capacities upwards (it doesn’t downgrade them to avoid a production environment being impacted with a default setting of an automated script).

Arguments [table_name] The table name of the dynamoDB to be created. [attribute_definitions] The dynamoDB attribute definitions to be used when the table is created. See the AWS documentation for details. [key_schema] The dynamoDB key definitions to be used when the table is created. See the AWS documentation for details. [read_capacity] The read capacity to configure for the dynamoDB table. [write_capacity] The write capacity to configure for the dynamoDB table.



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# File 'lib/lambda_wrap/dynamo_db_manager.rb', line 34

def publish_database(table_name, attribute_definitions, key_schema, read_capacity, write_capacity)
  
  has_updates = false
  
  # figure out whether the table exists

  begin
    table_details = @client.describe_table(table_name: table_name).table
  rescue Aws::DynamoDB::Errors::ResourceNotFoundException
  end
  
  if (table_details)
    wait_until_table_available(table_name) if (table_details.table_status != 'ACTIVE')
    
    if (read_capacity > table_details.provisioned_throughput.read_capacity_units ||
      write_capacity > table_details.provisioned_throughput.write_capacity_units)
      puts "Updating new read/write capacity for table #{table_name}. 
        Read #{table_details.provisioned_throughput.read_capacity_units} ==> #{read_capacity}.
        Write #{table_details.provisioned_throughput.write_capacity_units} ==> #{write_capacity}."
      table = @client.update_table({
        table_name: table_name,
          provisioned_throughput: { read_capacity_units: read_capacity, write_capacity_units: write_capacity }
          })
      has_updates = true
    else
      puts "Table #{table_name} already exists and the desired read capacity of #{read_capacity} and write capacity of #{write_capacity} has at least been configured. Downgrading capacity units is not supported. No changes were applied."
    end
  else
    puts "Creating table #{table_name}."
    ad = attribute_definitions || [{ attribute_name: "Id", attribute_type: "S" }]
    ks = key_schema || [{ attribute_name: "Id", key_type: "HASH" }]
    table = @client.create_table({
      attribute_definitions: ad,
      table_name: table_name,
      key_schema: ks,
      provisioned_throughput: {read_capacity_units: read_capacity, write_capacity_units: write_capacity}
      })
    has_updates = true
  end
  
  if (has_updates)
    wait_until_table_available(table_name)
    puts "DynamoDB table #{table_name} is now fully available."
  end

end