The document provides an introduction to Kubernetes, an open-source platform for automating the deployment, scaling, and management of containerized applications, emphasizing its architecture and key features such as automatic binpacking and self-healing. It outlines essential building blocks like pods, services, replication controllers, and volumes, as well as deployment patterns like canary updates and rolling updates. The document concludes with resources for further exploration of Kubernetes and invites questions from the audience.

1. Intro to KubernetesMiloš Simić :: NS BigData Meetup

2. Plan
• What is Kubernetes
• Architecture
• Building blocks
• Where to go next
• Questions
http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning-
framework-for-containers/

3. What is Kubernetes
• Kubernetes is an open-source system (written in Go) for automating
deployment, scaling, and management of containerized applications
• It groups containers that make up an application into logical units for easy
management and discovery.
• Kubernetes builds upon 15 years of experience of running production
workloads at Google, combined with best ideas and practices from the
community.
• Inspired and informed by Google’s experiences and internal systems (Borg
best name ever :D)
• Supports multiple cloud and bare-metal environments
• Supports multiple container runtimes
https://www.joyent.com/triton/compute

4. What can
Kubernetes
do
• Automatic binpacking
• Horizontal auto-scaling
• Automated rollouts and rollbacks
• Self-healing
• Application health checking
• …
• Manage applications, not
machines
http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning-
framework-for-containers/

5. We need a cluster
• Laptop to multi-node cluster
• Hosted or self managed
• On-Premise or Cloud Bare
• Physical or Virtual Machines
• Or bunch of Raspberry PIs
Raspberry pi kubernetes cluster

6. Architecture
• etcd overall state of the cluster at any given
point of time.
• The Controllers create, update and delete
the resources they manage (pods, service
endpoints, etc.)
• API server provides internal and external
interface to Kubernetes.
• Scheduler tracks resource utilization on each
node to ensure that workload is not scheduled
in excess of the available resources
• Kubelet is responsible for the running state of
each node (that is, ensuring that all containers
on the node are healthy). It takes care of
starting, stopping, and maintaining application
containers (organized into pods)
https://mesosphere.com/blog/kubernetes-and-the-dcos/

7. Building blocks
pods
• A Pod is the basic building block of
Kubernetes–the smallest and simplest unit in
the Kubernetes object model that you create
or deploy.
• A Pod represents a running process on your
cluster.
• A Pod encapsulates an application
container (or, in some cases, multiple
containers)
• Each Pod is assigned a unique IP addres
• Containers inside a Pod can communicate
with one another using localhost
• Pods are functionally identical and therefore
ephemeral and replaceable - no saved state image from Bryan Dorsey GOTO talk

8. Building blocks
service and labels
• Kubernetes Pods are mortal. They are born and
when they die, they are not resurrected.
• A Kubernetes Service is an abstraction which
defines a logical set of Pods and a policy by
which to access them.
• Service has static ip address
• Load balances incoming requests across
grouped pods
• Services find their group of Pods using Labels
• A Label is a key/value pair attached to
everything and convey user-defined attributes
• Metadata with semantic meaning and
Grouping Mechanism
• Query on labels to do things like dashboards
image from Bryan Dorsey GOTO talk

9. Building blocks
replication controller
• Replication Controllers ensure the
specified number of Pod “replicas”
are running at any one given time.
• Controll loop
• If one Pod dies then the
Replication Controller will replace
it to maintain a total count of
specified pods
• Have one job: ensure N copies of a
pod
• if too few, start new ones
• if too many, kill some
• group == selector
image from Bryan Dorsey GOTO talk

10. Building blocks
volumes
• If Pods are ephemeral how can I
persist my container data across
container restarts?
• Well, Kubernetes supports the
concept of Volumes so you can use a
Volume type that is persistent.
• Look like Directories to Containers
• Volume options
• mounted local storage device such
as a disk
• network file systems (and similar
services)
• Cloud Provider Block Storage
(Google, AWS, Azure)
image from Bryan Dorsey GOTO talk

11. Example
apiVersion: apps/v1beta1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 2 # tells deployment to run 2 pods matching the template
template: # create pods using pod definition in this template
metadata:
# name is not included in the meta data as a unique name is
# generated from the deployment name
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.7.9
ports:
- containerPort: 80
apiVersion: v1
kind: Service
metadata:
name: nginx-service
spec:
ports:
- port: 8000 # the port that this service should serve on
targetPort: 80
protocol: TCP
# just like the selector in the deployment,
# but this time it identifies the set of pods to load balance
# traffic to.
selector:
app: nginx
• To start working we describe our jobs in YAML or JSON
• Submit to master, he will schedule job for us somewhere in the cluster
• Pods and replication controllers could be merged into Deployments
kubectl create -f ./deployment.yaml kubectl create -f ./service.yaml

12. Patterns
• Canary update
• Only a part of the audience get access to the new version of the
app, while the rest still access the “old” version one.
• very useful when we want to be sure about stability in case of
any changes which may be breaking, and have big side effects.
• Rolling updates
• Rolling updates allow Deployments update to take place with
zero downtime by incrementally updating Pods instances with
new ones.
• New Pods will be scheduled on Nodes with available resources.

13. Where to go next
• kubernetes.io
• Google Kubernetes Engine
• Play with kubernetes
• hello Minikube, test on your
machine
• Read Borg and Omega
papers :)
https://github.com/kubernetes/minikube

14. Questions?
Thank you for your
attention :)
milossimicsimo@gmail.com@MilosSimicSimoMilosSimic
http://www.businesscloudnews.com/2016/06/02/emc-launches-storage-provisioning-
framework-for-containers/