Operations Driven Web Services-A Case Study of Service Evolution at Rent the Runway

Camille Fournier, Head of Engineering @skamille

Carlo Barbara, Senior Engineer @CarloBarbara

In The Beginning, There Was Drupal

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There was also all of these folks…

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Can’t Just Burn the World Down

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Hollow It Out!

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Complexity

Dec-1

1

Feb-

12

Apr-1

2

Jun-

12

Aug-

12

Oct-1

2

Dec-1

2

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13

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3

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1302468

101214

Number of Services in Production

Operations first…

Availability and performance of our services is critical to running our business

The software we develop has to make delivering on our SLAs possible

How (besides sane design): Healthchecks + Nagios Measurements Historical Data with Graphs

Metrics

Gauges – instantaneous value

Counters – counter with +/-

Meters – rate over time (mean, 1, 5, & 15 moving avg.)

Histograms – distribution of data (mean, median, max, std. div., 75th, 90th, 95th, 98th, 99th, & 99.9th percentiles)

Timers – Meter of requests & Histogram of duration (frequency & latency)

Metrics - Reporting

HTTP

JMX

Graphite

Dropwizard: What is it?

Quality open source Java webservice components glued together in a modular way

Eliminates the need for picking a platform stack, it’s all there

It’s opinionated. If you don’t like a Dropwizard core component, that’s too bad, don’t use Dropwizard

Developers focus on business logic, not framework

It’s easy, maintainable, and it works!

A Few Words from Coda…

“I had no one I had to toss a WAR to. I had no one to stand up a Tomcat server and fiddle with it until their eyes bled. I had no one who didn't trust me to spin up my own threads or connection pools. So I wrote something which worked as simply and in as straight-forward a manner as possible because my own ass was on the line if it didn't work.”

Dropwizard: The Ingredients

Jersey for REST

Jackson for JSON

Jetty for a webserver

Metrics for measuring

YAML for configuring

Dropwizard for weaving everything together

Dropwizard – Healthchecks

Register hooks that check the health of your app

An HTTP endpoint that iterates over all the hooks

“The meaning of healthy” is decided by you (i. e. Database Connections, Client Connections, DeadLock Count)

Dropwizard + Metrics

Dropwizard has lots of platform instrumentation baked in using Metrics, happens for free! (i.e. Jetty, JVM, Log Counts, etc…)

Ability to add Timers to your endpoints with @Timed

Ability to add arbitrary metrics as you see fit

Other Frameworks

Play 1.X Abandonware for Play 2.X, which was still beta Magic

Glassfish OSGI hell “standards”

Spring Everything and the kitchen sink Also I hate XML

What do I get out of it? Dev agenda

Story telling: causation & correlation

Integral piece of the operational excellence puzzle

State of the world – Dashboards

Developers focus on features, operations is mostly free lunch

Code review & demo

Disclaimer: You need graphite to really harness the value

Story telling

The grid is slow why? Is it load? Is it dependent service latency? How does that compare to yesterday

JVM throws out of memory, what’s the problem? What does the GC jigsaw look? When did it change? Is it correlated with increased load?

How is that new ‘performance’ tweak? If you never measured, then you didn’t tune. True story! What does my 5XX graph look like?

Operational Excellence: The ingredients

Application Instrumentation (Dropwizard)

Time Series Data & Graphing (Graphite, D3)

Centralized logging & log parsing (Rsyslog, Logstash, Nagios)

Automated alerting & escalation (Pagerduty)

DW & Graphite will get you very far, but if you want total control & visibility you need the rest. This is the stack that RTR is moving towards, rather than relying on basic java logging smtp appenders

OMG, we are on GMA, are we OK?

10+ services

Each services runs in a cluster behind an LB

‘OK’ is somewhat service specific

Basically you need a lot of info at your fingertips. Pictures are worth a thousand words. Get yourself some dashboards!

Graphite Dashboard

Tasseo dashboard (D3)

• Red, Yellow, & Green Lights• Realtime• Endless cool things: graphite + D3

If we see yellow or red, start diagnosing

Free Lunch? Really

DB connection pool monitoring

Http client connection pool monitoring

JVM Heap & GC info

Http Server response counts

Http Server connection info

Endpoint duration & throughput stats

Where do I sign up?

You install Graphite, one time hit + some TLC. Medium Difficulty

You annotate your endpoints and maybe add finer telemetry. Easy

You configure so your service is feeding into graphite. Hopefully consistently across services, via a ‘Bundle’. Easy

Demo

Show a simple dropwizard codebase 0.6.2 Slim Example: https://github.com/cab222/choco

0.7.0-SNAPSHOT Complete: https://github.com/dropwizard/dropwizard/tree/master/dropwizard-example

Do some curls

Show the admin endpoints

References

dropwizard.codahale.com

metrics.codahale.com

graphite.wikidot.com

Presenters

@CarloBarbara (www.cabkata.com)

@Skamille (whilefalse.blogspot.com)

Rent The Runway is hiring! (renttherunway.com/careers)