Introducing Kubernetes

Agenda
● Linux Containers
● Docker
● Kubernetes
● Kubernetes Architecture
● Kubernetes Demo

What is a container?
-Application and process delivery mechanism
-Stateless with all included dependencies
-Fast start, hyper dense, and portable

Linux Containers
• An operating
system–level
virtualization
method for running
multiple isolated
Linux systems
(containers) on a
single control host.

Linux Containers drawbacks:
• https://lwn.net/Articles/588309/
•Problem 1: effective virtualization.
•Problem 2: sharing resources among containers.
•Problem 3: making resource limits easy to understand.
•Problem 4: live migration.
•Problem 5: upstreaming.
•Problem 6: a common file system.
•Problem 7: inefficient storage.

Docker
● A platform for managing Linux Containers
● Began as an open-source implementation of the
deployment engine which powers Cloud
● Started in March 2013
● Provided an easy-to-use API and powerful container image
management features
● Attracted the community very fast

Problems with standalone
Docker
● Running a server cluster
on a set of Docker
containers, on a single
Docker host is vulnerable to
single point of failure!

Kubernetes:
 Kubernetes is amature open-source platform for hosting
Docker containers in a clustered environment with multiple
Docker hosts.
 Provides container grouping, load balancing, auto-healing,
scaling features.
 Based on learning from internal Google projects.
 Contributors == Google, CodeOS, Redhat, Mesosphere,
Microsoft, HP, IBM, VMWare, Pivotal etc.
 Extensible / flexible API architecture.

Key Concepts of Kubernetes:
 Pod - A group of Containers
 Labels - Labels for identifying pods
 Kubelet - Container Agent
 Proxy - A load balancer for Pods
 etcd - A metadata service
 cAdvisor - Container Advisor provides resource
usage/performance statistics
 Replication Controller - Manages replication of
pods
 Scheduler - Schedules pods in worker nodes
 API Server - Kubernetes API server

Pods:
The primary primitive for running containerized workload.
-Unit of scheduling / resource envelope
-May contain one or more containers
-Containers share network, volumes, isolation components

Pods Cont.
What does a pod look like?

Kubernetes Services
Kubernetes object expressing pod networking endpoint
(internal / external IP address).
-Service is associate with pod through label selector
-ClusterIP–exposed on cluster-internal IP
-NodePort–exposed on nodes IP .via static port
-LoadBalancer–exposed externally on providers NLB
-ExternalName–map service to DNS name

Kubernetes Manifest
YAML file to declare desired state of Kubernetes
object types.
-Define Kubernetes type
-Define type specification
-Labels / Annotations
-Metadata
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
labels:
app: nginx
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.14.2
ports:
- containerPort: 80

Kubernetes demo:
Kubernetes object expressing pod networking endpoint
(internal / external IP address).
-Service is associate with pod through label selector
-ClusterIP–exposed on cluster-internal IP
-NodePort–exposed on nodes IP .via static port
-LoadBalancer–exposed externally on providers NLB
-ExternalName–map service to DNS name

References:
 https://kubernetes.io/docs/home/
 https://confluence.wdc.com/x/g05RHw
 https://confluence.wdc.com/x/qZ_DIQ
 Others…

Introducing Kubernetes

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