Microservices… Yes or not?Eduard Tomàs – Dev @ Plain concepts@eiximenis

http://geeks.ms/etomas

#Gapand2017

Colaboradores

How we reach here?

N-tier apps

• Distributed aplications

• Implicit boundaries

• RPC-like

Common Object Request Broker Architecture

DCOM & DNA Architecture

RMI

…

SOA

• Services have explicitboundaries

• Services are autonomous

• Services share schema and contract, not classes

• Services interoperate based on policy

“Four SoA Tenets” by Don Box

• OASIS Web Services• WS-*

• SOAP

• Enterprise Service Bus (ESB)• WebSphere ESB

• BizTalk

• Oracle ESB

• …

Don Box @ Teched 2001 (BCN)

Microservices

The term "Microservice Architecture" has sprung up over the last few years to

describe a particular way of designing software applications as suites of

independently deployable services. While there is no precise definition of this

architectural style, there are certain common characteristics around organization

around business capability, automated deployment, intelligence in the endpoints,

and decentralized control of languages and data.

https://martinfowler.com/articles/microservices.html

Microservices - also known as the microservice

architecture - is an architectural style that structures an

application as a collection of loosely coupled services,

which implement business capabilities. The microservice

architecture enables the continuous delivery/deployment

of large, complex applications. It also enables an

organization to evolve its technology stack.

SOA vs Microservices

SOA Microservicios

Services are generally big Services are generally small

ESB centric role Usually no need for ESB

Favours orchestration over coreography Favours coreography over orquestration

Share as much as possible Share as Little as posible

OASIS WS-*, SOAP, XML, HTTP, … REST, HTTP, …

Who cares about SOA now? Everybody talks about Microservices!

Just one comparison…

But, the reality is…

https://www.youtube.com/watch?v=wgdBVIX9ifA

Microservices are a way to do SOA

SOAP vs REST

• Heavy message format: XML and <soap:Envelope> schema

• RPC based: service -> method (i.e. doctorSvc->GetAllPatients)

• Uses HTTP merely as transport protocol. Can use other transports.

• Small messages. No format assumed

• Resource based (i.e. /doctors/<id>/patients

• Embraces HTTP semantics: use HTTP verbs and return codes

Orchestration

• Main logic business belongs to a single central service (the orchestrator)

• Central service calls other services and combines its results

• Typical example: BPEL process

Coreography

• Logic distributed.

• No central point that coordinates other services

• Best with event source model

The 8 key aspects of Microservices (byFowler)

1. Componentization via Services

2. Organized around Business Capabilities

3. Products not Projects

4. Smart endpoints and dumb pipes

5. Decentralized Governance

6. Decentralized Data Management

7. Infrastructure Automation

8. Design for failure

https://martinfowler.com/articles/microservices.html

The 7 sins of Microservices

• LUST: Using the latest & greatest tech

• GLUTTONY: Excessive communication protocols

• GREED: All your Service are belong to us

• SLOTH: Creating a distributed monolith

• WRATH: Blowing up when bad things happen

• ENVY: The shared single domain fallacy

• PRIDE: Testing in the world of transcience

https://opencredo.com/the-seven-deadly-sins-of-microservices-redux/

LUST

• Do not believe that using the latest tech will solve all your problems

• Docker, k8s, Terraform, Swarm are great technologies

• But sometimes the right choice is to pick some old and boring techs

GLUTTONY

• HTTP, Protobuff, AMQP, 0MQ, gRPC, MQTT, …

• All are great communication protocols…

• …But not all together!

• Choose one synchronousprotocol…

• … And an asynchronous one

GREED

• Organization needs to adapt a “microservices culture”

• Each microservice belongs to specific team

• Deployment, technologies & tools, processes… are team responsabilities

SLOTH

• If you don’t change your mind and develop each microservice with using same patterns and decisions used to create monoliths

• You’ll finish not having microservices at all. Instead...

• You’ll have a set of microservices that can’t be deployed and updated independently

WRATH

• Failure happens all of time

• Must embrace DevOps mentality of shared understanding and responsibility

• Rapid provisioning, monitoring and deployment are mandatory pre-requisites

ENVY

• Using a Shared Single Domain is OK when developing a monolith

• In microservices is better to follow the DDD concept of ‘bounded context’ to encapsulate better our services

• Anyway: there is no rule. Don’t assume that one bounded context == one microservice

PRIDE

• Testing microservices is often harder (or much harder) than testing a monolith

• Test as much as you can in your CI/CD pipelines

• Unit tests, integration tests, component tests, end-to-end tests. Automate them all.

12 factor apps

https://12factor.net/

I - Codebase

• One codebase, many deploys

• If there is more than onecodebase, it is not an app, it is a distributed system

II - Dependencies

• Explicity declare and isolate dependencies

• 12 factor app never relies on the existence of “system-wide” packages

• All dependencies are declared by the app…

• … and a dependency isolation tool is required also

III - Config

• Store config in the environment

• Configuration vary between deploys. So can’t be part of the app

• Try to avoid config files, and never store them to repo

• Store configuration in environment variables

IV – Backing services

• A backing Service is any external Service consumed by the app (database, rabbitmq, external mail service,…)

• App must make not distinction between local and 3rd party backingservices

• All backing services are just attached resources that can be accessedthrough an URI

• Any backing Service can be changed from local to 3rd party at anytime, only changing configuration

V – Build, Release, Run

• Strictly separate the build & run stages

• A codebase is transformed to a deploy through 3 stages• Build stage: Creating an executable from source code

• Release stage: Deploying the executable to specific environment and applyconfig

• Run stage: Starts the app by starting specific executables on the environment

• These 3 stages must be completely isolaged (i. e. can’t change thecode during run or release stages)

VI - Processes

• Execute the app as one or more stateless processes

• Any app is stateless and share nothing. Any state must be stored in a stateful backing Service

• Using local storage and/or memory is OK, only if it used as a cache in a single request lifetime

• Sticky sessions are (of course) a violation of 12 factor apps

VII – Port binding

• Expose Services via port binding

• A 12 factor app is completely self-contained

• No runtime injection of any webserver or similar is allowed

• App expose its functionality using a configurable port

VIII - Concurrency

• Scale out via process model

• In 12 factor apps process is a 1st class citizen

• Scale using more processes, instead of any other way (like threads)

• As 12 factor apps are stateless and share nothing, concurrency and scale using processes is a safe and simple operation

IX - Disposability

• Maximize robustness with fast startup and graceful shutdown

• 12 factor apps are disposable: can be stopped at any momento

• App must shutdown gracefully at SIGTERM

• App should be robust when a sudden death happen (i. e. hardware failure)

X – Dev / prod parity

• Keep development, staging, and production as similar as possible

• App must be designed for Continuous deployment in mind: gap between prod and dev must be as small as posible

• Code authors are code deployers. No “deployment team”

XI - Logs

• Treat logs as event streams

• A twelve-factor app never concerns itself with routing or storage of its output stream

• App never manages its logfiles: just log to the stream

• Environment maps the stream wherever appropiate

XII – Admin processes

• Run admin/management tasks as one-off processes

• One-off admin processes should be run in an identical environment as the regular long-running processes of the app.

• Admin code must ship with application code to avoid synchronization issues.

When to use microservices?

Microservices are not a free lunch!

• Significant Operations Overhead

• Substantial DevOps Skills Required

• Implicit interfaces management

• Duplication Of Effort

• Distributed System Complexity

• Asynchronicity Is Difficult!

• Testability Challenges

So… when to use them?

• If your organization has a strong devops culture

• Microservices allow to break a very big monolith in small pieces. Eachpiece can be managed by one pizza team.

• Microservices biggest advantage is agility: you can update, test and deploy each microservice in an independent way.

Agility in Microservices

• Amazon is a heavy user of microservices

• A single shop product use case can interact with 100+ microservices

• Amazon deploy to production…

• Once each 11 hours

Agility in Microservices

• Amazon is a heavy user of microservices

• A single shop product use case can interact with 100+ microservices

• Amazon deploy to production…

• Once each 11 hours minutes

Agility in Microservices

• Amazon is a heavy user of microservices

• A single shop product use case can interact with 100+ microservices

• Amazon deploy to production…

• Once each 11 hours minutes seconds

Agility in Microservices

• NEVER try to use microservices if the organization do not have anstrong Devops culture

• NEVER try to use microservices if a CI/CD pipeline is not established

• Doing Microservices is harder then doing Monoliths. Onlyorganizations that do monoliths well have a chance to do microservices well.

So…

• Use Microservices if really need them

• Don’t use them only because Amazon and Netflix do (probably yourproblems and Amazon problems are not the same).

• Remember: There are not silver bullets

Finally: Serverless

• Serverless means that you don’t need to bother about server management

• A step forward than PaaS

• Services are exposed as functions(FaaS) which are very-micro services!

• Scale per invocation, not per server

• More on this GAPAND at 11:30 by @adiazcan & @shmancebo ;-)

Thanks!!! Eduard Tomàs – Dev @ Plain concepts@eiximenis

http://geeks.ms/etomas

#Gapand2017