why should i care about stateful containers?

Why should I care about stateful containers?

Luke MarsdenCTO, ClusterHQ

@lmarsden @clusterhq

Microservices are smashing up monolithic databases

Many more database instances, many more flavours

prod

staging in cloud 2

DR in cloud 3

hosted CIdev

laptop

Aren’t containers stateless?

12 factor apps

One platform

Dev/prod parity

Cloud services are effectively closed source

Portability

OK, who’s in?

Cattle vs. petsDeep dive

compute

local storage

infrastructure evolution1990s

servers with disks in

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

SAN storage

VM VM VM

infrastructure evolution2000s

vol vol vol

VMware hosts

virtualisation and shared storage

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

EBS

VM VM VM

infrastructure evolution2010s

cloudVMs no longer HA

vol vol vol

EC2Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

infrastructure evolution2010s

computelocal storage

on-prem “hyperconverged” or “SDS”eg OpenStack + Ceph or ScaleIO

VM

vol vol

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

infrastructure evolution2010s

computelocal storage

distributed databasesbare metal / cloud VMs + local storage

db

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

db

infrastructure evolution2010s

computelocal storage

distributed databases on SDS

vol vol

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

db db

infrastructure evolution2015

computelocal storage

distributed databases on SDSin container clusters

vol vol

Servers Volumes

Pets Pets

Cattle Pets

Cattle Cattle

db db

container scheduler

Servers Volumes What is it?

Pets Pets just crap

Cattle Pets storage orchestration

Cattle Cattleephemeral

stateful containers

Pet ~= HA provided by infrastructure/platformCattle ~= HA provided by application

Pros & consStorage orchestration• Run any database/stateful app• Storage layer responsible for

data resilience• Ops independent of database

types• Works within a storage zone

Ephemeral stateful containers• Requires distributed database(s)• Database-defined data resilience• Ops requires understanding each

data service• Can span storage zones

Ephemeral stateful

Storage orchestration

Why should data be pets when servers are cattle?

Relocatable

EBS/SDS/SAN…

Stateless things scale outStateful things scale up

Container can be a shard

You can mix and match stateful + stateless in a

container cluster

Use case: rebalance cluster

storagev1

compute

containerhost

(VM orbare metal)

c1 c2

container composer + scheduler + SD

v2

Use case: rebalance cluster

storagev1

compute

containerhost

(VM orbare metal)

c1 c2

v2

container composer + scheduler + SD

Use case: drain a node

storagev1

compute

containerhost

(VM orbare metal)

c1 c2

v2 v3

c3 c4

v4

container composer + scheduler + SD

Use case: drain a node

storage

compute

containerhost

(VM orbare metal)

v3

c3 c4

v4

v1

c1 c2

v2

container composer + scheduler + SD

Use case: drain a node

storage

compute

containerhost

(VM orbare metal)

v3

c3 c4

v4

v1

c1 c2

v2

container composer + scheduler + SD

Use case: HA when node fails

storagev1

compute

containerhost

(VM orbare metal)

c1

container composer + scheduler + SD

Use case: HA when node fails

storagev1

compute

containerhost

(VM orbare metal)

container composer + scheduler + SD

Use case: HA when node fails

storagev1

compute

containerhost

(VM orbare metal)

c1

container composer + scheduler + SD

Use case: speed up distributed database recovery

storagev1

compute

containerhost

(VM orbare metal)

c1

container composer + scheduler + SD

c2

container overlay network

v2

10.0.0.1 10.0.0.2

c3

v3

10.0.0.3

Use case: speed up distributed database recovery

storagev1

compute

containerhost

(VM orbare metal)

c1

container composer + scheduler + SD

c2

container overlay network

v2

10.0.0.1 10.0.0.2

c3

v3

10.0.0.3

Use case: speed up distributed database recovery

storagev1

compute

containerhost

(VM orbare metal)

container composer + scheduler + SD

c2

container overlay network

v2

10.0.0.2

c3

v3

10.0.0.3

Use case: speed up distributed database recovery

storagev1

compute

containerhost

(VM orbare metal)

container composer + scheduler + SD

c2

container overlay network

v2

10.0.0.2

c3

v3

10.0.0.3

c110.0.0.1

Connecting storage to containers

Try Flocker todayFor stateful microservices

luke@clusterhq.comclusterhq.com

github.com/clusterhq/flocker

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