Applications

• Hosted on a server
• Installed on the disk
• Run as processes
• Provide a service
• Quality of service

A single application running on a host

Containers

• Standardised
• Isolated
• Easily distributed
• Improved security

A single container running on a host

Docker

• Docker is a container platform
• Standard for containers
• Not a hypervisor
• Docker Hub is a library

Multiple containers

• All isolated from one another
• Managed interactions
• Workload control
• Security

A single host running multiple containers side-by-side

Things go wrong

• Hosts crash
• Goal is quality service delivery:
  • Reliability
  • Performance
  • High-availability
• Redundant copies

Multiple Docker hosts behind a load balancer

More to manage

• Config management
  • Networking
• Secret distribution
• Simplicity of load balancer
• Identical nodes
  • Non-adaptive
• Need help orchestrating

Kubernetes

Kubernetes

• Container orchestration
• Networking
• Services
  • Load balancing
  • High availability
• Ingress
• Secret management

A Kubernetes pod wrapping a single container

Kubernetes entities

• Pod
  • Wraps a container
• Deployment
  • Defines pod and how it's deployed to cluster
  • Multiple instances of a pod
  • Multiple different pods

Multiple Kubernetes pods deployed across multiple hosts

Kubernetes entities

• Services
  • Routed across multiple pods
  • Hide underlying implementation

Services broker requests to an orchestrated set of pods

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