From Docker To Kubernetes: A Developer's Guide To Containers - Mandy White - Codemotion Roma 2015

A Developers Guide to Containers and Google Cloud Platform

Codemotion Rome - March 2015Mandy Waite - Google Developer Relations Engineer

@tekgrrl

Containers, containers, everywhere

Containers at Google

Brief intro to Docker

Google Container Engine (Demo)

1

2

3

4

Agenda

Containers

Feedback: goo.gl/FTHOv7 Twiitter: @tekgrrl


● Lightweight environment for running applications

● Hermetically sealed static binaries

○ No External Dependencies

● Isolated applications running on a single host

○ Resources, Users, Filesystem, Network

● Moves us from “Idealized Hardware” to an “Idealized OS”

What is a container?


Implemented on top of a number of (unrelated) Linux APIs:

cgroups: Restrict resources a process can consume

CPU, memory, disk IO, ...

namespaces: Change a process’s view of the system

Network interfaces, PIDs, users, mounts, ...

capabilities: Limits what a user can do

mount, kill, chown, ...

chroots: Determines what parts of the filesystem a user can see

What makes Containers Possible?


Why Should Developers Care?

Static application environment

= reliable deployments

No stress deployment

Repeatable, runnable artifact

= portability

Develop here, run there

Pick your cloud solely on its merits

Loosely coupled

= easier to build and manage

Compose applications from micro-services

Facilitates re-use


Hypervisor

Guest environment

app code

libraries

guest os

Vanilla virtualizationIdealized Hardware


It has downsides:No Isolation

Hypervisor

Guest environment

app code

libraries

guest os

dependency???app code


It has downsides:Little Reuse

Hypervisor

Guest environment

app code

libraries

guest os

Guest environment

app code

libraries

guest os

Guest environment

app code

libraries

guest osredundant


Containers create a better abstraction layer

Hypervisor

Guest environment

app code

libraries

guest os

cut here


Node environment

Portable, isolated, static app environments, Idealized OS

Hypervisor

node os

app code

libraries

app code

libraries

app code

libraries

container 1 container 2 container 3

Containers at Google


● Gmail, Web Search, Maps, ...

● MapReduce, batch, ...

● GFS, Colossus, ...

● Even GCE itself: VMs in containers

Images by Connie Zhou

Everything at Google runs in a container


● Performance

● Repeatability

● Isolation

● Quality of service

● Accounting

● Visibility

● Portability

Why Google Likes Containers


Managed Base OS

Node Container Manager

Scheduled Containers

Cluster Scheduler

Google Internal cluster management stack

Docker


Docker - Bringing Containers to the Mainstream


More Popular than Fernando Alonso (ex Ferrari Driver)


But what is Docker?

An implementation of the container idea

A package format

An ecosystem

A company

An open-source juggernaut

A phenomenon

Container Image

Dependencies

App Code


Docker Swarm

Spotify Helios

CoreOS Fleet

Kubernetes

Orchestrating Docker Containers

Kubernetes

Container Cluster Anyone?

Images by Connie Zhou

$ gcloud preview container clusters create guestbook


Greek for “Helmsman”; also the root of the word “Governor”

• Orchestrator for running Docker containers

• Supports multi-cloud environments

• Inspired and informed by Google’s experiences and internal systems

• Open source, written in Go

Manage applications, not machines

Kubernetes


Cluster: A group of nodes on which containers are scheduledContainer: A sealed application package (Docker)Pod: A small group of tightly coupled Containers

example: content syncer & web server

ReplicationController: A loop that drives current state towards desired state

Service: A set of running pods that work togetherexample: load-balanced backends

Labels: Identifying metadata attached to other objectsexample: phase=canary vs. phase=prod

Selector: A query against labels, producing a set resultexample: all pods where label phase == prod

Key Concepts


node 1

f0118

node 3

node 4node 2

d9376

b0111

a1209

Kubernetes Cluster

node 5

c8743

node 3

node 4node 2

x5621

b0111

a1209


Small group of containers & volumes

Tightly coupled

The atom of cluster scheduling & placement

Shared namespace• share IP address & localhost

Ephemeral• can die and be replaced

Example: data puller & web server

Pods

Pod

File Puller Web Server

Volume

ConsumersContent Manager


Dashboard

show: FE

● Metadata with semantic meaning● Membership identifier● The only Grouping Mechanism

➔ Allow for intent of many users (e.g. dashboards)➔ Build higher level systems … ➔ Queryable by Selectors

Behavior Benefits

Pod Pod

frontend

Pod

frontend

Pod Pod

FE FE v2

Dashboard

show: v2

more at labels.md

Labels

https://github.com/GoogleCloudPlatform/kubernetes/blob/e7922489ac7b9879d4175fb46ba3a9914f4bf1ac/docs/labels.md


Behavior Benefits

ReplicationController

#Pods → 2label selector: v1

Pod Pod

frontend

Pod

frontend

Pod Pod

v1 v1

ReplicationController

#Pods → 1label selector: v2

v2

● Keeps Pods running● Gives direct control of Pod #s

➔ Recreates Pods, maintains desired state

➔ Fine-grained control for scaling

more at rc.md

Replication Controllers

https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/replication-controller.md



Replication Controller- Name = “nifty-rc”- Selector = {“App”: “Nifty”}- PodTemplate = { ... }- NumReplicas = 4

API Server

How many?

3

Start 1 more

OK

How many?

4

Canonical example of control loops

Have 1 job: ensure N copies of a pod● if too few, start new ones● if too many, kill some● group == selector

Replicated pods are fungible● No implied ordinality or identity


node 1

f0118

node 3

node 4node 2

d9376

b0111

a1209

Replication Controller- Desired = 4- Current = 4



node 1

f0118

node 3

node 4node 2


d9376

b0111

a1209



node 1

f0118

node 3

node 4


b0111

a1209



node 1

f0118

node 3

node 4


b0111

a1209

c9bad



node 1

f0118

node 3

node 4node 2


d9376

b0111

a1209

c9bad



node 1

f0118

node 3

node 4node 2


d9376

b0111

a1209

c9bad



A group of pods that act as one == Service• group == selector

Defines access policy• only “load balanced” for now

Gets a stable virtual IP and port• called the service portal• also a DNS name

VIP is captured by kube-proxy• watches the service constituency• updates when backends change

Hide complexity - ideal for non-native apps

Services

Portal (VIP)

Client


Kubernetes StatusOpen sourced in June, 2014

• won the BlackDuck “rookie of the year” award• so did cAdvisor :)

Google launched Google Container Engine (GKE)• hosted Kubernetes• https://cloud.google.com/container-engine/

Roadmap:• https://github.com/GoogleCloudPlatform/kubernetes/blob/master/docs/roadmap.md

Driving towards a 1.0 release in O(months)• O(100) nodes, O(50) pods per node• focus on web-like app serving use-cases

Google Container Engine- Inspired by a decade within Google - Reimagines Cluster computing- Designed for a multi-cloud world

Photo by Connie Zhou


Let’s build something

Guestbook PHP App

Redis Worker

Redis Worker

Redis Master

Guestbook PHP AppGuestbook

PHP App


Demo


Kubernetes is Open SourceWe want your help!

http://kubernetes.iohttps://github.com/GoogleCloudPlatform/kubernetes

irc.freenode.net #google-containers@kubernetesio

http://kubernetes.io

http://kubernetes.io

https://github.com/GoogleCloudPlatform/kubernetes

https://github.com/GoogleCloudPlatform/kubernetes


Local Meetups

Docker Roma Meetup

GDG Roma LAB


Feedback: goo.gl/FTHOv7Tweet Me questions: @tekgrrl

Questions

plus.google.com/+MandyWaite

Thank you!

Software

From Docker To Kubernetes: A Developer's Guide To Containers - Mandy White - Codemotion Roma 2015