Analytics on write with AWS Lambda

Unified Log London, 4th November 2015

Introducing myself

• Alex Dean

• Co-founder and technical lead at Snowplow, the open-source event analytics platform based here in London [1]

• Weekend writer of Unified Log Processing, available on the Manning Early Access Program [2]

[1] https://github.com/snowplow/snowplow

[2] http://manning.com/dean

Analytics on read, analytics on write

It’s easier to start by explaining analytics on read, which is much more widely practised and understood

1. Write all of our events to some kind of event store

2. Read the events from our event store to perform some analysis

In analytics on write, the analysis is performed on the events in-stream (i.e. before reaching storage)

• Read our events from our event stream

• Analyze our events using a stream processing framework

• Write the summarized output of our analysis to some storage target

• Serve the summarized output into real-time dashboards, reports etc

Analytics on write and analytics on read are good at different things, and leverage different technologies

With a unified log powered by Kafka or Kinesis, you can apply both analytical approaches to your event stream

• Apache Kafka and Amazon Kinesis make it easy to have multiple consuming apps on the same event stream

• Each consuming app can maintain its own “cursor position” on the stream

Getting started with analytics on write

What are some good use cases for getting started with analytics on write?

Low-latency operational reporting, which must be fed from the incoming event streams in as close to real-time as possible

Dashboards to support thousands of simultaneous users, for example a freight company might share a a parcel tracker on its website for customers

Others? Please share your thoughts!

1

2

?

Analytics on write is a very immature space – there’s only a handful of tools and frameworks available so far…

PipelineDB• Analytics on write (“continuous views”) using SQL• Implemented as a Postgres fork• Supports Kafka but no sharding yet (I believe)

amazon-kinesis-aggregators• Reads from Kinesis streams and outputs to DynamoDB & CloudWatch• JSON-based query recipes• Written by Ian Meyers here in London

Druid• Hybrid analytics on write, analytics on read• Very rich JSON-based query language• Supports Kafka

… or we can implement a bespoke analytics on write solution – for example with AWS Lambda

• The central idea of AWS Lambda is that developers should be writing functionsnot servers

• With Lambda, we write self-contained functions to process events, and then we publish those functions to Lambda to run

• We don’t worry about developing, deploying or managing servers –instead, Lambda takes care of auto-scaling our functions to meet the incoming event volumes

An AWS Lambda function is stateless and exists only for the side effects that it performs

Designing an analytics on write solution for OOPS

Let’s imagine that we have a global delivery company called OOPS, which has five event types

OOPS management want a near-real time dashboard to tell them two things

Where are each of our delivery trucks now?

How many miles has each of our delivery trucks driven since its last oil change?

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2

In DynamoDB, we could represent this as a simple table

All we need to do is write an AWS Lambda function to populate this DynamoDB table from our event stream…

… however a more efficient approach is to apply some old-school map-reduce to the micro-batch first

What do we mean when we talk about conditional writes in DynamoDB?

Bonus: DynamoDB’s conditional write syntax is very readabledef conditionalWrite(row: Row) {

val vin = AttrVal.toJavaValue(row.vin)

updateIf(vin, "SET #m = :m",

"attribute_not_exists(#m) OR #m < :m",

Map(":m" -> AttrVal.toJavaValue(row.mileage)),

Map("#m" -> "mileage"))

for (maoc <- row.mileageAtOilChange) {

updateIf(vin, "SET #maoc = :maoc",

"attribute_not_exists(#maoc) OR #maoc < :maoc",

Map(":maoc" -> AttrVal.toJavaValue(maoc)),

Map("#maoc" -> "mileage-at-oil-change"))

}

for ((loc, ts) <- row.locationTs) {

updateIf(vin, "SET #ts = :ts, #lat = :lat, #long = :long",

"attribute_not_exists(#ts) OR #ts < :ts",

Map(":ts" -> AttrVal.toJavaValue(ts.toString),

":lat" -> AttrVal.toJavaValue(loc.latitude),

":long" -> AttrVal.toJavaValue(loc.longitude)),

Map("#ts" -> "location-timestamp", "#lat" -> "latitude",

"#long" -> "longitude"))

}

}

Demo

To simplify the demo, I performed some configuration steps already (1/2)

1. Downloaded the Scala code from https://github.com/alexanderdean/Unified-Log-Processing/tree/master/ch11/11.2/aow-lambda

2. Built a “fatjar” for my Lambda function ($ sbt assembly)

3. Uploaded my fatjar to Amazon S3 ($ aws s3 cp …)

4. Ran a CloudFormation template to setup permissions for my Lambda, available herehttps://ulp-assets.s3.amazonaws.com/ch11/cf/aow-lambda.template

5. Registered my Lambda function with AWS Lambda ($ awslambda create-function …)

To simplify the demo, I performed some configuration steps already (2/2)

6. Created a Kinesis stream ($ aws kinesis create-stream

…)

7. Created a DynamoDB table ($ aws dynamodb create-

table …)

8. Configured the registered Lambda function to use the Kinesis stream as its input ($ aws lambda create-event-

source-mapping --event-source-arn

${stream_arn} --function-name AowLambda --

enabled --batch-size 100 --starting-position

TRIM_HORIZON)

Finally, let’s feed in some OOPS events…

host$ vagrant ssh

guest$ cd /vagrant/ch11/11.1

guest$ ./generate.py

Wrote DriverDeliversPackage with timestamp 2015-01-11 00:49:00

Wrote DriverMissesCustomer with timestamp 2015-01-11 04:07:00

Wrote TruckArrivesEvent with timestamp 2015-01-11 04:56:00

Wrote DriverDeliversPackage with timestamp 2015-01-11 06:16:00

Wrote TruckArrivesEvent with timestamp 2015-01-11 07:35:00

… and check our Kinesis stream, Lambda function and DynamoDB table

Resources and further reading

Further reading

Chapter 11, Analytics on write

Manning Deal of the Day today!

Discount code: dotd110415au (50% off just today)

• https://www.pipelinedb.com/

• https://github.com/awslabs/amazon-kinesis-aggregators/

• http://druid.io/

• https://github.com/snowplow/aws-lambda-nodejs-example-project

• https://github.com/snowplow/aws-lambda-scala-example-project

• https://github.com/snowplow/spark-streaming-example-project

Questions?

http://snowplowanalytics.com

https://github.com/snowplow/snowplow

@snowplowdata

To meet up or chat, @alexcrdean on Twitter or alex@snowplowanalytics.com