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background-image: url(elephant_jog.jpg)

Elephants on Automatic

.sigblock[ Josh Berkus, Red Hat

Oleksii Kliukin, Zalando

Kubecon EU 2017 ]

.leftlogo[ redhat logo

zalando logo ]

state station

Getting to State

Stateless Now

nginx scaling

1.5: StatefulSet

  1. storage
  2. identity
  3. discovery

Not Quite Enough

  • "cluster join"
  • failover
  • special nodes
  • rebalancing

Custom Schedulers?

  • not packaged with app
  • kube expertise needed
  • message lag

running robot

Bot Pattern

Bot Pattern

  • control daemon in node
  • runs as PID 1 in container
  • communicates via consensus
    or kube api

Bot Tasks

  • initialization
  • joining cluster/group
  • failover
  • telemetry

Bot Examples

  • governor
  • Patroni
  • entrypoint.py
  • Joyent's ContainerPilot

elephant Vader helm

Helm

Helm Adds

  • parameterization
  • deploy multiple instances
  • app registry
  • support for sidecars

Examples

  1. Patroni/Spilo
  2. CitusDB

Patroni

  • HA PostgreSQL controller
  • Etcd, Zookeeper or Consul
  • Spilo = Patroni + PostgreSQL

spilo_diagram

Extensibility

  • callbacks
  • custom replica creation methods
  • pluggable consistent KV-stores

More than autofailover

  • synchronous mode
  • cascading replication
  • dynamic configuration

Cluster maintenance

  • "Hands-off" mode
  • Scheduled failovers and restarts

Interfaces

  • REST API
  • patronictl

Helm parameters

  • cluster name
  • Etcd host
  • number of replicas
  • credentials

Patroni Demo

patroni demo

citus sharded

CitusDB

Sharded Parallel Postgres

  • sharded Postgres
  • partition data over nodes
  • shards duplicate for redundancy
  • query node distributes queries
  • mainly for data mining (big data)

shard diagram

StatefulSet Setup

  • one query node (node 0)
  • 2 to N shards
  • service for query node only

Simple Bot

  • if node 0, query node
  • if not node 1, register with query node
  • updates Kubernetes label for discovery
  • (auto rebalancing not OSS, yet)

Helm Params

  • cluster name
  • cluster size
  • storage allocation
  • passwords

Citus Demo

Pull Requests Welcome!

github.com/zalando/patroni

github.com/jberkus/atomicdb

Resources

  • This Presentation:
    jberkus.github.io/container_cluster
  • Simplified Configuration Scripts:
    github.com/jberkus/atomicdb/

Spilo Resources

  • Patroni Project:
    github.com/zalando/patroni
  • Spilo Project:
    github.com/zalando/spilo
  • Helm Chart:
    github.com/kubernetes
    /charts/incubator/patroni

Spilo demo:

  • Helm Chart:
    github.com/alexeyklyukin/
    /charts/incubator/patroni

¿questions?

.left-column-narrow[ more
jberkus:

project atomic:

  ]

.right-column-wide[ @fuzzychef
www.databasesoup.com
jberkus.github.io

www.projectatomic.io

  ]

.leftlogo[rh logo]

.rightlogo[cc by sa]

Photo Credits

Giant rideable robot elepant courtesy of The Nantes Project: http://www.lesmachines-nantes.fr/en/
Darth Vader elephant helm created by Blank William: http://www.blankwilliam.com/
The running robot with elephant cartoon by Mark F. Stosiak: http://www.markstosiak.com/