This document provides an overview of Kubernetes networking and storage capabilities. It begins with an agenda that includes a deep dive on Kubernetes networking and persistent volumes, as well as live demos of persistent storage and another topic. The document then discusses Kubernetes networking at the host level using pods that share IP, IPC, and disk, as well as inter-host networking solutions like OpenShift SDN. It also covers Kubernetes persistent volume claims that allow administrators to provision storage and developers to request storage that is independent of the underlying devices. The document concludes with demos of storage and another topic.

1. Networking & Storage Deep Dive
Ken Thompson
Senior Cloud Solution Architect
Melbourne Docker Meetup - October 2015
KUBERNETES: THE HELMSMEN

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Agenda
Kubernetes Deep Dive
● Kubernetes Networking
● Kubernetes Persistent Volumes
● Live Demos:
– Persistent Storage
– Something Fun!...

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Container orchestration at scale
KUBERNETES
● Scale workloads across a cluster of
container hosts
● Declarative state of environment
that gets managed
● Intelligent policy-based scheduling
● Multi-host networking support (with
OpenShift-SDN/OvSwitch etc.)
● Multi-host shared storage for
containers
● Image update mechanisms (with
OpenShift Deployment Configs -
rolling update, a-b, etc.)

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KUBERNETES DEEP DIVE:
NETWORKING

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DOCKER IN-HOST NETWORKING
Suitable for single-host, not for multi-host
● Docker assigns an IP to each
container
● Its local and private only by default
● Complex for multi-host
● Plugins starting to become available
● Now we have a container..hold on!
– What happens If we want to
have containers sharing
filesystem
– Or IPC communications
– Or localhost communications
(mysql & phpmyadmin for eg.)
eth0
Linux bridge: docker0: 172.17.42.1/16
vethXXX
172.17.x.x/16
container
eth0
vethXXX
172.17.x.y/16
container
eth0

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KUBERNETES IN-HOST NETWORKING
Kubernetes Pods
● Pods (aka gears in OSE v2)
– Pod typically runs only one
container for independent scaling,
with exceptions such as “sidecars”.
Ie. MySQL & phpMyAdmin
– Same IP / network namespace
– Same IPC
– Ability to share disk
– Scheduled on same machine
– Atomic unit
– Can listen (to other containers)on
127.0.0.1 or 0.0.0.0

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INTER-HOST NETWORKING
Solutions Available
PROGRAMMABLE
INFRA
● GCE – each host gets a
subnet of 256 Ips
● AWS 40-100 Ips per
host
● Custom enterprise
networking
OVERLAY NETWORKS
● Flannel (ie. Atomic
Host) – subnet with
simple overlay.
● Others solutions
available like Weave,
etc.
Open vSwitch
● OpenStack
● Very large
deployments
● Programmable
● OpenShift-SDN uses
this

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● Kubernetes assigns 10.1.x.0/24 subnet to pods in each node
● Gateway IP 10.1.x.1 is assigned to lbr0
● Out of the box with OpenShift, Open vSwitch VXLAN overlay is used to connect nodes/pods
● Flat network, allow subdivision via flows
OPENSHIFT-SDN NETWORKING
OVS: br0
vxlan0
eth0
vovsbr
Linux bridge: lbr0: 10.1.0.1/24
vlinuxbr
veth pair
vethXXX
Pod
10.1.0.2
eth0
vethXXX
Pod
10.1.0.3
eth0VXLAN
VXLAN overlay
OVS: br0
vxlan0
eth0
vovsbr
Linux bridge: lbr0: 10.1.1.1/24
vlinuxbr
veth pair
vethXXX
Pod
10.1.1.2
eth0
vethXXX
Pod
10.1.1.3
eth0
10.1.1.0/24
VXLAN

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● OpenShift-SDN or similar overlays allow communications within a cluster, but how do
access from outside; ie. WWW?
● Router Pod – Runs HAproxy, proxies incoming traffic through SDN – HTTP/S Only
OPENSHIFT-SDN ROUTING

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KUBERNETES DEEP DIVE:
STORAGE

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DOCKER STORAGE CONSTRAINTS KUBERNETES GOALS
CONTAINER STORAGE
1) Containers are ephemeral
(stateless), once they disappear, so
does the data
2) You can mount the host filesystem,
but
1) What about loss of host?
2) How do you scale across
1000s of hosts?
3) How is this data shared?
1) Allow administrators to describe
available storage
2) Allow application developers to
discover and request persistent
storage
3) Persistent storage should be
available without being closely
bound to a particular disk, server,
network or storage device
4) Support iSCSI, NFS, EBS, Gluster,
Ceph… and many more!
Problem Statement

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PERSISTENT VOLUME CLAIMS
● Admins add PVs to cluster [1]
● Like Pods, PVClaims live in a
namespace
● Pods [3] and Pvclaims [2] are
requests for resources by users
● Users request resources with
limits, like cpu usage by a
container or storage capacity of a
volume [2]
● OpenShift binds requests to
available resources
● Multiple access modes
(RWO,ROM,RWM)
Requests for storage
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
name: myclaim
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 8Gi
kind: Pod
apiVersion: v1
metadata:
name: mypod
spec:
containers:
- name: myfrontend
image: dockerfile/nginx
volumeMounts:
- mountPath: "/var/www/html"
name: mypd
volumes:
- name: mypd
persistentVolumeClaim:
claimName: myclaim
POST:
kind: PersistentVolume
apiVersion: v1
metadata:
name: pv0001
spec:
capacity:
storage: 10
nfs:
Server: srv.com
path: /data/path
1 2
3

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DB
Host 1 Host 2
Storage Pool
Kubernetes Persistent Volumes
CONTAINER STORAGE
mysql-claim
pv0001
Network Storage NFSiSCSI EBS RBD
2. Dev “Claims” PV
1. Admin creates PV

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DB
Host 1 Host 2
DB
What happens to a container & its storage when a node is lost?
CONTAINER STORAGE
Storage Pool
mysql-claim
pv0001
Network Storage NFSiSCSI EBS RBD

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What happens to a container & its storage when a node is lost?
CONTAINER STORAGE
DB
Host 1 Host 2
DB
Storage Pool
mysql-claim
pv0001
Network Storage NFSiSCSI EBS RBD

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Storage Demo
(https://github.com/openshift/origin/tree/master/examples/wordpress)
&
HexBoard Demo
(https://www.youtube.com/watch?v=wWNVpFibayA&feature=youtu.be&t=24m25s)

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Free Kubernetes eBook
OpenShift Enterprise Test-Drive
(Free 8 hour Environment on AWS)
Questions?
http://red.ht/1NbW2wi http://red.ht/1MQVgqb
Plus some great ways to get started with Kubernetes...

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APPENDIX

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WHAT ARE LINUX CONTAINERS?
Software packaging concept that typically includes an application and all of
its runtime dependencies
● Easy to deploy and portable
across host systems
● Isolates applications on a
host operating system
● In RHEL, this is done through:
● Control Groups (cgroups)
● Kernel namespaces
● SELinux, sVirt, iptables
● Docker
HOST OS
SERVER
CONTAINER
LIBS
APP

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TRADITIONAL OS VS. CONTAINERS
Traditional OS Containers
HARDWARE
HOST OS
HARDWARE
HOST OS
CONTAINER
LIBS
APP A
LIBS A LIBS B LIBS LIBS
APP A APP B
CONTAINER
LIBS
APP B
Packaged dependencies = faster boot times + greater portability

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Developers can access OpenShift via Web, CLI or IDE
OPENSHIFT 3
Turn-key solution for Developer Productivity + Container Orchestration