Running stateful services in containers - ContainerDays Boston 2016

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RUNNING STATEFUL SERVICES IN CONTAINERSJONAS ROSLAND, EMC {code}DEVELOPER ADVOCATE & COMMUNITY MANAGER


• How are Container Platforms managed?• Handling stateless apps and stateful services• Everything running in containers• Making the platforms understand data persistence

AGENDA


• Clustered servers• Manual deployments• Redundancy, not necessarily high availability

BACK IN THE OLD DAYS


• Infrastructure as a Service• Deploy virtual machines• Manual/half-automated way of deploying apps• Almost efficient

THEN SOME TIME AGO


• Collection of compute resources• Spread out horizontally• Brings scale to your deployments

NOW – CONTAINER PLATFORMS


Standard definitions


APPLICATIONS RUN IN CONTAINERS

Code Code andrequirements Container


• Manages all physical/virtualresources• Deploys and schedules apps• Handles hardware failures

RESOURCE MANAGERS AND SCHEDULERS


SCHEDULING


PAAS SITS ON TOP OF SCHEDULERS


• Enables apps and infrato automatically findparts of each other• Keeps track of how to

connect and use theapplication services

SERVICE DISCOVERY


SERVICE DISCOVERY

Java App

2.3.4.5:8080 Where isJava App?2.3.4.5:8080


You don’t have torewrite your apps!


• Storing data (state) is a critical component of any application• Where they store this state defines their class

– Connected database– In memory– Local disk

APPLICATION STATE DIFFERENCES


• Store no critical data locally• Can be scaled as needed• Recovers quickly

STATELESS APPLICATIONS


• Services that store state• Have usually been treated as HA apps• Can be scale-out or scale-up

STATEFUL SERVICES


FROM oraclelinux:latest

ENV PACKAGE_URL https://repo.mysql.com/yum/mysql-5.7-community/docker/x86_64/mysql-community-server-minimal-5.7.12-1.el7.x86_64.rpm

RUN rpmkeys --import http://repo.mysql.com/RPM-GPG-KEY-mysql && yum install -y $PACKAGE_URL && yum install -y libpwquality && rm -rf /var/cache/yum/*

RUN mkdir /docker-entrypoint-initdb.d

VOLUME /var/lib/mysql

COPY docker-entrypoint.sh /entrypoint.sh

ENTRYPOINT ["/entrypoint.sh"]

EXPOSE 3306 33060

CMD ["mysqld"]

MYSQL IN A CONTAINER


APPLICATIONS BUILT FROM SERVICESFront End or Non-Persistent

Data Services (Persistent)

Scal

e-Up

Scale-Out

CassandraPostgresRedis CouchDB

Elastic SearchHadoop

MariaDB

Mysql

Nginx

HAProxy

MongoDB

RabbitMQTomcat

Memcached

ScaleIO ECS

ApacheRails

Language Specific HTTP


• No!– Without proper storage mapped, the service will lose data– Data doesn’t travel with the service if it’s stored on local

disk• Yes!

– Automatically mapping modern storage backends delivered by EMC, AWS, GCE, OpenStack and othersenables your data to be stored safely

STATEFUL SERVICES IN CONTAINERS?


• Have been mostly focused on stateless apps• Working hard on making stateful services part of

their inventory• So how do you handle both types?

CONTAINER PLATFORMS


• Data is stored outside the platform

EXAMPLE 1


• Data is stored on the same platform

EXAMPLE 2


Virtual Machine

PERSISTENCE AND P3

Platform 2 Platform 3

High Availability

Live Migration

Highly Available

Container Platform

Lifecycle Management

Container Platform

Lifecycle Management


Making the platformunderstand storage


• When a container starts, we can map storage to it• For apps such as databases this is a necessity• When a container stops, the storage is unmounted

and can be reused by another container

HOW DOES STORAGE IN CONTAINERS WORK?


• Local storage locks the container’s data on one server• Using non-local storage gives us the possibility to

move containers across servers• Having that possibility is crucial for HA environments

WHY NOT USE LOCAL STORAGE?


LET’S START WITH THE BASICS

GCE

?

AWSEMC OpenStack


SAY HELLO TO MY LITTLE FRIEND – REX-RAY


NOW WE’RE GETTING SOMEWHERE

GCEAWSEMC OpenStack


AND NOW IT’S GETTING INTERESTING

GCEAWSEMC OpenStack

Mesos Kubernetes


• Gives you the possibility to use any storage platform, and even multiple platforms at the same time• Always in sync with Docker’s development cycle• Integrated with Docker, Mesos and Kubernetes

REX-RAY BENEFITS

Running stateful services in containers - ContainerDays Boston 2016

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