Why containers?

• Resources
• Self-contained apps
• Portability
• Security (?)

Application anatomy

• Web server
• Application server
  • Login service
  • Profile service
  • Comment service
• Database

Pets vs cattle

Microservices

• Independent components
  • Scale
  • Upgrade
  • Iterations
• Polyglot application stack

Containers on scale

$ssh host1
host1# docker run container
$ssh host2
host2# docker run container
$ssh host3
host3# docker run container

Running containers on scale is a challenge.

Container orchestration

• Container lifecycle management
• Load balancing
• Health checks
• Observability (logs, metrics, traces)

Borg

• Kuberneted predecessor
• Developped at Google

https://kubernetes.io/blog/2015/04/borg-predecessor-to-kubernetes/

What is Kubernetes?

Container orchestration platform

Pods

• Group of containers
• Shared network space
• Smallest scalable unit

https://kubernetes.io/docs/concepts/workloads/pods/

Deployments

• Rolling upgrades
• Desired state: how many replicas should be running of a given pod?

Services

An abstract way to expose an application running on a set of Pods as a network service

https://kubernetes.io/docs/concepts/services-networking/service/

Ingress

Set of rules to direct inbound traffic to services.

https://kubernetes.io/docs/concepts/services-networking/ingress/