CDK for tagging model lambda

LambdaFunctions.ts

function setupAutoTripTagging(parentStack: BackendAPIStack) {
  const databaseUsernameSecret = new Secret(parentStack, 'databaseUsername');
  const databasePasswordSecret = new Secret(parentStack, 'databasePassword');

  const tripTaggingModelBucket = new Bucket(parentStack, 'gofar-auto-trip-tag-models');

  // sklearn etc. are MASSIVE and therefore exceed the lambda
  // limit (250MB). We upload the dependencies to S3 instead and the lambda will pull it down
  const rebuildModelDependencies = new Asset(parentStack, 'rebuildAutoTaggingModelLambdaDependencies', {
    path: './handlers/auto_trip_tagging_model_builder/dist/lambda_dependencies.tar.gz'
  });

  // Package lambda separately to speed up deployment process - we'll change the lambda
  // handler more often than the dependencies
  const rebuildAutoTaggingModelLambda = new Asset(parentStack, 'rebuildAutoTaggingModelLambda', {
    path: './handlers/auto_trip_tagging_model_builder/dist/build_tag_model_lambda.tar.gz'
  });

  const rebuildAutoTaggingModelSlimHandler = new Function(parentStack, 'rebuildAutoTaggingModelSlimHandler', {
    runtime: Runtime.PYTHON_3_7,
    handler: 'slim_handler.lambda_handler',
    memorySize: 512,
    code: Code.fromAsset('./handlers/auto_trip_tagging_model_builder/slim_handler'),
    deadLetterQueueEnabled: true,
    timeout: cdk.Duration.minutes(2),
    reservedConcurrentExecutions: parentStack.props.rebuildTagsModelConcurrencyLimit,
    vpc: parentStack.vpc,
    environment: {
      MODEL_LAMBDA_DEPENDENCIES_BUCKET_NAME: rebuildModelDependencies.s3BucketName,
      MODEL_LAMBDA_DEPENDENCIES_KEY: rebuildModelDependencies.s3ObjectKey,
      MODEL_LAMBDA_BUCKET_NAME: rebuildAutoTaggingModelLambda.s3BucketName,
      MODEL_LAMBDA_KEY: rebuildAutoTaggingModelLambda.s3ObjectKey,
      MODEL_BUILDER_FUNCTION: 'handler',
      MODEL_BUILDER_MODULE: 'build_tagging_model',
      TRIP_TAGGING_MODEL_BUCKET_NAME: tripTaggingModelBucket.bucketName,
      DB_PORT: parentStack.database.dbInstanceEndpointPort,
      DB_NAME: parentStack.props.databaseSchemaName,
      DB_HOSTNAME: parentStack.database.dbInstanceEndpointAddress,
      DB_USERNAME: databaseUsernameSecret.secretArn.toString(),
      DB_PASSWORD: databasePasswordSecret.secretArn.toString()
    }
  });

  parentStack.rebuildTaggingModelQueue.grantConsumeMessages(rebuildAutoTaggingModelSlimHandler.role as IRole);
  databaseUsernameSecret.grantRead(rebuildAutoTaggingModelSlimHandler.role as IRole);
  databasePasswordSecret.grantRead(rebuildAutoTaggingModelSlimHandler.role as IRole);

  rebuildModelDependencies.grantRead(rebuildAutoTaggingModelSlimHandler.role as IRole);
  rebuildAutoTaggingModelLambda.grantRead(rebuildAutoTaggingModelSlimHandler.role as IRole);
  tripTaggingModelBucket.grantPut(rebuildAutoTaggingModelSlimHandler.role as IRole);
  tripTaggingModelBucket.grantRead(rebuildAutoTaggingModelSlimHandler.role as IRole);
  tripTaggingModelBucket.grantDelete(rebuildAutoTaggingModelSlimHandler.role as IRole);

  rebuildAutoTaggingModelSlimHandler.addEventSource(
    new SqsEventSource(parentStack.rebuildTaggingModelQueue, {
      batchSize: 1
    })
  );
}