Studio Lambda

🚀 A custom AWS Lambda execution environment for local testing. Runs each Lambda function in it's own process. Integrates with Studio Gateway.

Usage

const Lambda = require('@studio/lambda');

const lambda = Lambda.create();
lambda.invoke('some-lambda', { some: 'event' }, callback);

API

• lambda = Lambda.create([options]): Returns a new Lambda controller for the given options.
  • base_dir: The base directory to use. Defaults to the current working directory.
  • lambda_path: The path to the Lambda function. Replaces ${LAMBDA_NAME} with the Lambda name. Defaults to functions/${LAMBDA_NAME}/.
  • env: An object with environment variables to use. Defaults to an empty object.
  • config_file: A JSON file with additional environment and timeout properties. Defaults to functions/${LAMBDA_NAME}/function.${AWS_PROFILE}.json. Placeholders in the form of ${ENV_VAR} are replaced with the corresponding environment variable.
  • timeout: The default Lambda timeout to use in milliseconds. Defaults to 5 seconds.
  • memory: The default Lambda memory to use in MB. Defaults to 128 MB. This will set --max-old-space-size on Lambda processes.
  • max_idle: The idle timeout to use in milliseconds. If a function is not invoked for this time, the process gets destroyed. Defaults to 1 hour.
• lambda.invoke(lambda_name, event[, options][, callback]): Invokes the named Lambda handle function. If no callback is given, a promise is returned. These options are supported:
  • awsRequestId: The AWS request ID to use in the Lambda context. If a context is given, but one of the above properties is missing, they are added to the context.
• lambda.shutdown([options]): Shut down all processes. These options may be given:
  • graceful: Wait for running instances before closing processes. If this is not set to true, all processes are killed immediately.
• lambda.stats(): Returns stats for this lambda instance. Returns an object where the keys are the Lambda function names and each value is an object with these properties:
  • instances: The total number of instances running.
  • active: The number of instances currently handling requests.
  • requests: The total number of requests received.

Lambda context

Lambda function are invoked with (event, context[, callback]) where the context has this interface:

• functionName: The name of the Lambda function.
• invokedFunctionArn: The function ARN, build from the AWS_REGION (defaulting to us-east-1), STUDIO_AWS_ACCOUNT (defaulting to 000000000000) and the Lambda function name.
• memoryLimitInMB: The configured memory limit.
• awsRequestId: The AWS request ID, either from options or generated.
• getRemainingTimeInMillis(): Returns the remaining time until the Lambda function times out.

If callback is not defined (the lambda handler function has an arity < 3), the function is expected to return a promise.

Debugging Lambda functions

If the environment variable STUDIO_LAMBDA_INSPECT is set to the name of a Lambda function, the node process for that function will be called with --inspect and the timeout value is ignored. This prints a Chrome debugger URL to the console. With this setup in place, you can add debugger statements to place breakpoints.