Will it blend?JointOpenStackKubernetesEnvironment

A pragmatic operational assessment of if and when Kubernetes can become an underlay for OpenStack.

TL;DR: Not today. In the future, yes.

Rob Hirschfeld (aka Zehicle online)

In Community: OpenStack Board Member (4 years)

Co-Chair of Kubernetes Cluster Ops SIG

Founder of Digital Rebar & Crowbar Projects

Professional: CEO of RackN - hybrid automation software

Executive at Dell - scale data center ops

Cloud Data Center Ops going back to 1999

Addressing Operators Needs

Operational Success is Essential to Project Success

Operators are not developers!

Simple, Transparent and Stable are key concerns

Becoming a super-user of the platform should not be required to run it

Scale & Upgradability has both internal and external drivers

Generally, Kubernetes has good operational fundamentals

We’re Talking Underlay, not Overlay

We’re talking about installing Kubernetes first (aka underlay) and using it to manage the OpenStack control plane.

This approach is not a win if we

● Disable Kubernetes management● Still need outside management tooling

For now, we’ll ignore that our user may actually want to use Kubernetes as the overlay. IMHO, a bad assumption. Physical Infrastructure

KubernetesUnderlay

OpenStack

KubernetesOverlay

This Talk

Simplest conception of the K8s OpenStack Sandwich

What is Kubernetes?

Container Scheduler (no, it’s not really Orchestration)

API driven to provide restart, placement, network routing and life-cycle

For Applications designed for Kubernetes

Key Design Elements: Immutable Infrastructure (stateless ops)

12 Factor Configuration

Service Oriented

What is Kubernetes: A Three Tier Application

Client

0Ready

1Prereq

2Control

3Nodes

etcd(cluster)etcd

(cluster)etcd

(cluster)

API(cluster)

API(cluster)

API(cluster)

Kubelet

KubeCtl

Container Manager

5Apps

Network CNI

HostNetwork

HostStorage

HostInit

Pod Pod Pod Pod

4Add-Ons

CertificateAuthority

Scheduler(leader)

Heapster

InfrastructureAPIs

Routers,Storage,

LBs...

Proxy

...

Controller(leader)

DNS Watcher ...

Together 4ever: API server + Kubelet

Client

0Ready

1Prereq

2Control

3Nodes

etcd(cluster)etcd

(cluster)etcd

(cluster)

API(cluster)

API(cluster)

API(cluster)

Kubelet

KubeCtl

Container Manager

5Apps

Network CNI

HostNetwork

HostStorage

HostInit

Pod Pod Pod Pod

4Add-Ons

CertificateAuthority

Scheduler(leader)

Heapster

InfrastructureAPIs

Routers,Storage,

LBs...

Proxy

...

Controller(leader)

DNS Watcher ...

Kubernetes = Rainbows?!

Why do we want Kubernetes as Underlay?

Community Perception Accuracy

1 OpenStack Operations is still really hard True

2 We already do most deploys in containers Partially

3 Kubernetes is awesome at containers Partially

4 Kubernetes means free Upgrades and High Availability False

5 Kubernetes is simple, stable and secure (for operators) False

First: We’re Confusing Technical and Marketing

Marketing around Kubernetes under OpenStack is a “hot mess”

● People heard “Kubernetes is stable, OpenStack is not”● Further confuses “OpenStack one platform message”

Who is promoting doing this? Mirantis / CoreOS / Intel / Google

Confusion with the Plain Old Container Install (“POCI”) message

● Canonical (Ubuntu Cloud Install), ● Rackspace (OpenStack Ansible)● Cisco (Kolla)

Second: Why I’m scared

This discussion keep kicking the operations & install problems down the field

Kubernetes is much newer than OpenStack, so even less understood

Yet more complexity and some very basic questions:

● Now we have a both a Kubernetes and OpenStack upgrade problem● We still need tooling to manage OpenStack in Kubernetes● We still need someone to package the containers● Relies on Docker to keep systems running● Storage and Networking are still being worked out

But, it’s going to happen anyway…So let’s get pragmatic about it.

Key Principle: Containerization vs Kubernetes

Containers can be treated as a) lightweight vms or 2) packaged daemon sets.

● Canonical builds their containers like persistent vms and configures with Juju● Kolla & OSA treats containers as packaging and configures with Ansible

Kubernetes accepts neither approach – they expect containers to be immutable and 12 factor configured

● Kubernetes manages the full container life-cycle● Containers need to be able to handle being added, removed ● Services need to be able to handle IP address changes (or use DNS names)

Specific Technical Barriers

Host / Pinned vs Managed Containers

● It is possible to disable Kubernetes management and pin containers ● This eliminates the desired benefit of using Kubernetes

How to handle Layered SDN integrations? Who wins?

How to handle expectations of container persistence?

Assumptions of Exclusive Ownership / Administrative Control

General Challenges to Overcome

Complexity● Overall Complexity of More Components● Need to Control Kubernetes & Kubernetes Stability

● Need for Multiple Tiers of Load Balancer● IP Mobility in Service Registration & Message Bus● Mixed Networking Models

● Utility Upgrades and maintenance of the Underlay● Mixing Kubernetes workloads

Networking

Utility

There are REAL Potential Benefits

Part of Kubernetes Ecosystem (which is likely bigger than OpenStack’s)

Leverage Docker packaging efforts and reduce Python & O/S dependencies

Upgrades would benefit from Kubernetes built-in processes

Use of the Kubernetes job scheduler for maintenance

“Free” fault tolerance of key components

Easier install if Kubernetes already running on-site

More constrained options for configuration and operation

How could this actually be done quickly?

Focus on Control plane, leave the nodes alone.

● Workers are “pinned” and agents need administrative control

Cherry pick services to move into Kubernetes

● Focus on web services● Separate support services (data & message bus)

Externalize data using service registry

Physical Infrastructure

KubernetesUnderlay

OpenStackMgmt

OpenStackNodes

Sup

port

Ser

vice

s

Make sure OpenStack Projects can handle immutable container requirements

More Detail: Ops Underlay vs OpenStack Underlay

Physical Infrastructure

Kub

erne

tes

Con

trolle

rs

OpenStackMgmt OpenStack

Nodes

Dat

abas

e

If you to really want to build this, give me a call - RackN has all the components

Mes

sage

Bus

Software Defined NetworkingKubernetes

WorkersLoad

Bal

ance

r

In summary,

OpenStack operability is not solved via the underlay platform alone.

Technical Leadership motivation required for OpenStack adopting Kubernetes architecture requirements.

Serious messaging confusion in effort has to be resolved.

However, this collaboration is required for OpenStack

Because Kubernetes will have a larger footprint in Operations