This document provides an overview of Kubernetes, a container orchestration system. It begins with background on Docker containers and orchestration tools prior to Kubernetes. It then covers key Kubernetes concepts including pods, labels, replication controllers, and services. Pods are the basic deployable unit in Kubernetes, while replication controllers ensure a specified number of pods are running. Services provide discovery and load balancing for pods. The document demonstrates how Kubernetes can be used to scale, upgrade, and rollback deployments through replication controllers and services.

1. Kubernetes

2. @erialc_w
● ops at Treeptik:
- CloudUnit: Java PaaS based on
Docker
● orchestration:
- on a single host with docker-
compose
- on a containers cluster:
Kubernetes, mesos, swarm...

3. I. Docker and Kubernetes
II. Kubernetes concepts
III. Demo

4. Before Docker
● Dedicated machines for each service
● Management (Chef, Puppet, Salt,
Ansible…)
● Machines (physical, cloud)
● app dependencies, scaling, upgrade,
rollbacks...

5. Docker Containers
Container
● process isolation
● namespace isolation
● own network interface
● own filesystem
Microservice
● one container = one
process

6. Docker Compose
● orchestrate containers
● links
● volumes-from
● on a single host !!!

7. Docker Swarm
● Pool of Docker hosts
● Native clustering:
extends the
Docker API

8. Kubernetes Clusters
● Open source
● (Very!) Active
development
● Scheduler: cluster
orchestration
system

9. II. Kubernetes concepts

10. Key concepts
Pod
● smallest deployable unit
● shared context
Label
● key/value pair
● organize, select objects
Replication Controller
● N pods running
● pod template
Service
● targets pods
● long-lived

11. Pods
Pod
Webserver
Content
Management
Server
● Set of containers
● Settings in a template
● Flat shared networking
namespace
● Shared storage volumes

12. Labels
● Metadata with semantic meaning
● Label selector
set of objects

13. Replication controllers
Replication
Controller
#Pods: 2
label selector: v1
Replication
Controller
#Pods: 1
label selector: v2
Pod Pod
Pod
v1 v1
v2
● Keeps pods running
● Direct control of pods

14. Services
Service
label selector: FE
Pod
FE
● Automatically configured load balancer
● Stable address
● Decoupled from controller
Replication
Controller
#Pods: 2
label selector: FE,
v1
v1
Pod
FE
v1

15. Scaling
Service
label selector: FE
Pod
FE
Replication
Controller
#Pods: 2
label selector: FE,
v1
v1
Pod
FE
v1
Pod
FE
v1
Replication
Controller
#Pods: 3
label selector: FE,
v1

16. Rolling update
Service
label selector: FE
Pod
FE
Replication
Controller
#Pods: 3
label selector: FE,
v1
v1
Pod
FE
v1
Pod
FE
v1
Replication
Controller
#Pods: 2
label selector: FE,
v2
v2 v2

17. III. Demo

18. Problems solved
● dependencies
● upgrade
● scale
● rollbacks

19. Kubernetes architecture
Node
kubelet proxy
docker
Pod
Master
API
scheduler
replication
controller
distributed
storage
kubectl
Pod