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 13

def initialize
  # 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)
  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

#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 and 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.

key_schema

The dynamoDB key definitions to be used when the table is created.

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 40

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
    # skip this exception because we are using it for control flow.
    table_details = nil
  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

      set_table_capacity read_capacity, 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' }]
    @client.create_table(table_name: table_name, key_schema: ks, attribute_definitions: ad,
                         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

#set_table_capacity(table_name, read_capacity, write_capacity) ⇒ Object 



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# File 'lib/lambda_wrap/dynamo_db_manager.rb', line 18

def set_table_capacity(table_name, read_capacity, write_capacity)
  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}."
  @client.update_table(
    table_name: table_name,
    provisioned_throughput: { read_capacity_units: read_capacity, write_capacity_units: write_capacity }
  )
end