Experiences with Microservices at Tuenti

.Experiences with Microservices at

Aarón FasAndrés Viedma

Microservices?

I know what you’re probably thinking...

Who did you say these guys are?

Andrés Viedma@andres_viedma

Aarón Fas@aaronfc

Javadinosaur

Useless gadgets buyer

From Social Network...

To Mobile Operator(full MVNO)

The PHPMonolith

One single source repository

PHP???

Do you need a release?

Take a ticketand wait...

.Microservices

Microservices… again… (and take a shot)

❖ Distributed, independently deployable components

❖ Well defined interfaces

❖ Simple communication interface (HTTP?)

❖ Each service has its own DB

❖ Each service has its own source repository






❖ Each service has its own source repository

THAT ISSOA !!!






❖ Each service has its own source repositoryIs that important enough to deserve a new name???

Mixing technologies

❖ Allows using different languages

❖ Different platform versions

❖ Incremental technology changes / evolution

Separation of responsibilities

❖ Forces separation of responsibilities

➢ Subsystems with well defined facades

➢ Different source repositories

Separation of responsibilities

❖ Forces separation of responsibilities

➢ Subsystems with well defined facades

➢ Different source repositories

YOU DON’T NEED MICROSERVICES!

USE JARS !!!

Continuous deployment

«Our highest priority is to satisfy the customerthrough early and continuous deliveryof valuable software.»

«The best architectures, requirements, and designsemerge from self-organizing teams.»

-- Principles of the Agile Manifesto

Continuous deployment

«Our highest priority is to satisfy the customerthrough early and continuous deliveryof valuable software.»

«The best architectures, requirements, and designsemerge from self-organizing teams.»

-- Principles of the Agile Manifesto1 Service => 1 Team?

Better than Continuous delivery!:Continuous deployment

Team responsible of the deployments?

Beware! High costs

❖ No transactions!

➢ Distributed tx?

❖ Requires a much more complex infrastructure

❖ Difficult integration testing

For us: Seemed like a good idea

❖ We have small self-organized teams => Continuous deployment is a reality

❖ We wanted Java, we had PHP

❖ Strong SRE / DevOps team

❖ Our software was intended mainly to access 3rd parties => transactions not possible anyway

.Communications protocol

Existing libraries

❖ No PHP implementation➢ Avro, Etch, Netflix stack

❖ Only serialization➢ Protocol buffers

❖ Didn’t exist or were too new➢ Cap’n Proto, gRPC

❖ Thrift?➢ Good option, but a lot of PHP boilerplate

TService

❖ Own abstraction layer - RPC based❖ Basic implementation: JSON-RPC❖ Interface Definition Language (IDL)❖ Generates Java / PHP / Erlang:

➢ Interchange objects

➢ Client

➢ Server stub

TService IDL/** * Manages the transfer of balance between subscriptions. * @version 1 */interface BalanceTransferService {

/** Transfer money from one subscription to another one. */String transfer(Donation donation) throws NoSuchSubscriptionException;(...)

}

/** Donation between two subscriptions. */class Donation {

/** Id of the donor */long from;/** Amount of money to transfer */int amount;(...)

}

class NoSuchSubscriptionException extends Exception {int code = 100;

}

Java???

TService Versioning

Interface v1

Service

Client 1

Client 2

(compatible changes)

● New methods● New fields in objects

● New parameters in methods

● Delete methods / parameters / fields

TService Versioning

Interface v1

Service

Interface v2

Client 1

Client 2

(compatible changes)

.Java Platform

Technology stack

XConfig

❖ Own configuration system❖ YAML files based❖ Git repository❖ Overriding system: by env, common / service❖ Hot reloading

➢ Everything adjusts to changes: even DB pools!

➢ No restart required

Async jobs

TService request processing Enqueue

job

Queued jobs

Executor thread pool

Async jobs

TService request processing Enqueue

job

Queued jobs

Executor thread pool

Cron jobs

Cron jobs programming in config

Feature disabling

❖ Activation / deactivation of features by config➢ Is the new development risky?

➢ Is the rest of services / environment ready for the change?

❖ Partial activation of a feature for a % of users➢ Incremental activation of an optional risky change

➢ A / B tests

Integration tests

❖ Custom JUnit runner➢ Bootstraps the platform

➢ Cleans / restarts the local database

➢ Allows the use of @Inject in tests

➢ Allows overriding in dependency injection => inject mocks of the other services

❖ Uses special, “development” XConfig repo

.Monitoring

Monitoring, a priority

❖ What is happening or has happened?➢ Logs

➢ Metrics

➢ Alarms

❖ Distributed architectures are much more difficult to track

And basically because...

.Let’s talk about logs

Logging

❖ Logging library in Java?➢ Log4j

❖ We needed full details➢ Filters to expand/simplify information logged

➢ Multiple appenders logged into distinct storages

❖ Overview of appenders

Logging

log.info(...); Logger

MySQL Appender

LogStash Appender

Hadoop Appender

❖ Following call’s path (TService calls logging)

Logging

ServiceA ServiceB ServiceCGlobalID = 100RequestID = 1

GlobalID = 100RequestID = 2

GlobalID = 100RequestID = 3

Benefits● Locate in/out for calls● Get all interactions

Logging

❖ Kibana dashboard

What does it look like?

Change query

Customize filters

Log types by color

Full log details

.Let’s talk about metrics

Metrics

❖ We graphs➢ As easy as possible to track new metrics

❖ Do not reinvent the wheel➢ Already using StatsD/Graphite on PHP side

❖ What are we tracking?➢ Basic monitoring metrics added by the platform

➢ Metrics from Tomcat JMX

➢ Metrics related to business

Metrics

❖ Multiple graphs dashboards tested➢ Default graphite one

➢ Grafana

Graphite’s is a little ugly...

Grafana is prettier

Layout customized

Much better UI to create graphs

.Let’s talk about alarms

Alarms

❖ Graphs are ok, but we don’t have people 24x7 staring at them.➢ We need notifications

❖ Different things to monitor➢ SQL queries

➢ Graphite metrics

➢ HTTP requests

➢ ...

Alarms

❖ Created our own alarms system➢ Multiple data sources and easily extensible

➢ Quick edition of conditions

➢ Observers for alarms

❖ We ended up using mainly➢ MySQL and Graphite data sources

➢ Java Expression Language on config checkers

➢ Email notifications

… and then, we found Cabot

Separated by service

Cabot overview

Multiple integrations

Cabot overview

Service status overview

Cabot overview

Graphite checks

Cabot overview (Creating new check)

Set graphite metric


Check data


Set check type/value


Set importance

Cabot

❖ Benefits of using Cabot➢ Friendlier UI than config files➢ No dependency on the service monitored➢ Opensource and many integrations

Alarms

❖ Where are we heading now?➢ Moving now most Graphite alarms to Cabot

➢ Replacing thresholds with dynamic expectations (Holt Winters)

❖ It is still the main alarms platform being used

.That’s all about monitoring

.Some Lessons learned

GO ASYNC!!!

Don’t get blocked for too long

❖ Concurrent requests: don’t wait for free threads➢ Own Rate limit mechanism

➢ Tune container thread pool size

➢ Tune database pool (and other possible blocking pools)

❖ Tune clients timeout➢ It may depend on called service / operation

➢ It may depend on the caller

Asynchronous logging

log.info(...)Appender MySQL

Appender Logstash

AppenderHadoop

Logger


log.info(...)

When the ring buffer is full…WAIT!

Appender MySQL

Appender Logstash

AppenderHadoop

Logger

Ring buffer

Async Logger

Not configurable!


log.info(...)

When the ring buffer is full…WAIT!

Appender MySQL

Appender Logstash

AppenderHadoop

Logger

Ring buffer

Async Logger

Async Appender

Async Appender

Async Appender

Not configurable!

When async appender full, messages are discarded

Asynchronous operations

❖ Getters➢ Make them fast (sacrifice consistency)

➢ Cache

➢ Use default values

❖ Setters➢ No operation result

➢ Wait for a notification of operation finished

➢ Query the status of the change

Message queues

❖ Operation queues➢ Retry system

➢ Persistent queues

❖ Publish / subscribe model (pub/sub)➢ Event driven

➢ Reactive programming

Circuit breaker

❖ From the client, consider the status of the service➢ Previous calls

➢ Health checks

❖ If it’s degraded, don’t call it (close the circuit)➢ Return a default response

➢ Enqueue the operation for later retry

➢ Throw an error

.Do It Yourself

Many implementations available

❖ Communication layer➢ gRPC, Cap’n proto, Thrift…

➢ REST, JSON…

❖ Services platform➢ Spring boot, Dropwizard, Spark, Ninja, Jodd…

❖ Netflix stack➢ Hystrix, Ribbon…

Make your own combination!

(it can’t be so difficult…)

Aarón Fas@aaronfc

Andrés Viedma@andres_viedma

.Thanks!Questions?

Experiences with Microservices at Tuenti

Software

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