@laconia/invoke

@laconia/invoke

🛡️ Laconia Invoke — Invokes Lambdas like regular functions

Features

• Convention over configuration: Set environment variables and you are good to go
• Predictable user experience: Avoid common Lambda invocation programming error

Here are the user experience improvements that @laconia/invoke does for you:

• Automatically stringifying JSON request payload and parsing JSON response payload
• Throwing an error when FunctionError is returned instead of failing silently
• Augmenting stacktrace in the FunctionError thrown based on the stacktrace returned by Lambda invocation
• Set the FunctionError object's name and message thrown based on the error returned by Lambda invocation
• Throwing an error when statusCode returned is not expected

Install

npm install --save @laconia/invoke

Convention over configuration

One of the philosophy of Laconia is convention over configuration. You can use @laconia/invoke by simply setting environment variables and the creation of invoke function will be done automagically and injected to your LaconiaContext.

The environment variable that you set must follow this convention:

LACONIA_INVOKE_VARIABLE_NAME: lambdaName

@laconia/invoke will scan all environment variables that start with LACONIA_INVOKE and inject the invoke instances to LaconiaContext. The name of the instances will be extracted from the environment variable name, then converted to camel case. The instance you'll get in your LaconiaContext from the above configuration will be variableName.

Example usage:

Set your lambda environment variable:

LACONIA_INVOKE_CALL_CAPTURE_CARD_PAYMENT_LAMBDA: capture-card-payment

Once the environment variable is set, you will be able to invoke capture-card-payment lambda by registering the envVarInstances function provided by @laconia/invoke:

const invoke = require("@laconia/invoke");
const laconia = require("@laconia/core");

const handler = async ({ captureCardPaymentLambda }) => {
  await captureCardPaymentLambda.requestResponse();
};

module.exports.handler = laconia(handler).register(invoke.envVarInstances());

API

invoke.envVarInstances

Scans environment variables set in the current Lambda and automatically creates instances of invoke. To be used together with @laconia/core.

Example:

const invoke = require("@laconia/invoke");
const laconia = require("@laconia/core");

const handler = async ({ captureCardPaymentLambda }) => {
  /* logic */
};

module.exports.handler = laconia(handler).register(invoke.envVarInstances());

Manual instantiation

An instance of invoke can be created manually when the CoC style provided does not satisfy your need.

API

invoke(functionName, options)

• functionName specifies the Lambda function name that will be invoked
• options:
  • lambda = new AWS.Lambda()
    • Optional
    • Set this option if there's a need to cutomise the AWS.Lambda instantation
    • Used for Lambda invocation

Example:

// Customise AWS.Lambda instantiation
invoke("name", {
  lambda: new AWS.Lambda({ apiVersion: "2015-03-31" })
});

Invocations

API

requestResponse(payload)

Synchronous Lambda invocation.

• payload
  • The payload used for the Lambda invocation

Example:

invoke("fn").requestResponse({ foo: "bar" });

fireAndForget(payload)

Asynchronous Lambda invocation.

• payload
  • The payload used for the Lambda invocation

Example:

invoke("fn").fireAndForget({ foo: "bar" });