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 



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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

  @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 37

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 84

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 107

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 142

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
        at_exit do
          unlock
        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 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 137

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 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 70

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 96

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 



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# File 'lib/rbcli/stateful_systems/storagetypes/remote_state_connectors/dynamodb.rb', line 66

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 121

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
  @scheduler = nil
end