@bitgenics/honey-lambda-logger

honey-lambda-logger

The problem

Lambdas are amazing, but as soon as you have more than a handful of them logging & monitoring them becomes unwieldy. Creating alarms for every individual lambda isn't really an option and creating one for all lambdas is an exercise in frustration.

Cloudwatch: "Your threshold of 3 errors in 5 minutes is breached"
Me: That is bad! Which ones are giving errors?
Cloudwatch: "Your threshold of 3 errors in 5 minutes is breached"
Me: But where are the errors?!
CLoudwatch: "Your threshold of ... "
Me: Aaarrrrggghhhhh..

The Solution

This library is designed to wrap all NodeJS invocations and automagically suck all metadata into honeycomb. 90% of your data needs can be met with a quick:

const hll = require('@bitgenics/honeycomb-lambda-logger')

const handler = async (event, context) => {
  .....//Your regular lambda
}

module.exports = hll(handler)

NOTE! Currently honey-lambda-logger only works on async handlers and ignores the node6 callbacks or even early context.done type callbacks.

Configuring

Configuring hll is done through two environment variables

• HONEYCOMB_WRITE_KEY: Your write key for Honeycomb.
• HLL_DATASET: And surprise surprise, the Dataset to log to.

Customizing

We do give you a lot of control of what exactly should go to Honeycomb. Here are the options you can pass to hll(handler, options)

• meta: An object that gets passed to honeycomb as-is. Use this for any static information about the Lambda, such as what module it is from.
• transformEvent: Function with signature (event) => {}. We automatically extract any AWS specified metadata supplied in the event and context objects. But this function allows you to extract data from the event payload.
• transformResult: Function with signature (result) => {}. We do not automatically log anything from the return value of the handler. If you do want to log something, this is your chance.
• transformErr: Function with signature (err) => {}. We already log everything on the Error object, but maybe you want it in a different format?
• rethrowErr: Boolean, default true. Whether or not to rethrow the error after logging it.
• parseMetadata: Boolean, default true. If you don't want to parse the metadata associated with the event, you can disable it here.

Log Output

Context

For more information on most of these settings, see: https://docs.aws.amazon.com/lambda/latest/dg/nodejs-prog-model-context.html

Name	Description
context.accountId	The AWS accountId running the Lambda.
context.awsRequestId	The identifier of the invocation request.
context.callbackWaitsForEmptyEventLoop	Send response immediately without waiting.
context.functionName	The name of the Lambda function.
context.functionVersion	The version of the function.
context.invokedFunctionArn	The Amazon Resource Name (ARN) used to invoke the function.
context.invokeid	context.awsRequestId, but different?
context.logGroupName	The log group for the function.
context.logStreamName	The log stream for the function instance.
context.logUrl	A URL to the correct LogStream with a filter for this request.
context.memoryLimitInMB	The amount of memory configured on the function.
context.region	The region the Lambda ran in.

General

Name	Description
cold_start	Is this a cold start of the function?
costInMicroDollar	The cost in microDollars. The $ price of a million requests
costUnits	1 cost unit = lowest possible charge: 100ms of 128Mb Lambda
durationInMs	How long the execution took in milliseconds
err	The error object
likely_timeout	250ms before the lambda times out we log an event with likely_timeout set
remainingMs	How many milliseconds are left

Events

If we can determine what type of event triggered the Lambda we will log as much as information as we can. Currently we only parse DynamoDB and SNS Notifications. We are working on API Gateway and S3 events.

All (some?) events

Name	Description
event_meta.accountId	The AWS accountId of the source of the event.
event_meta.awsRegion	Region of the source.
event_meta.eventSource	The system responsible for the trigger (ie aws:sns)
event_meta.eventSourceARN	ARN of the source of the event.
event_meta.eventVersion	Event version.
event_meta.records_length	The amount of records in this event.

DynamoDB events

Name	Description
event_meta.dynamodb.StreamViewType	The StreamViewType of the DynamoDB Stream.
event_meta.dynamodb.records	Array of Objects with all Key, eventName and eventID for every record

SNS events

Name	Description
event_meta.sns.MessageAttributes.	There is a column for every MessageAttribute and their value
event_meta.sns.MessageId	MessageId
event_meta.sns.TopicArn	Arn of the SNS Topic the notification is from.
event_meta.sns.Type	Type of message.