Microservices

Definition

• Separate business logic functions.
• Instead of one big problem, several smaller applications.
• Communicative via well defined APIs - usually HTTP
• In demand

Advantages and Disavantages

• Advantages
  • Language independent
  • Fast iterations
  • Small teams
  • Fault Isolation
  • Pair well with containers
  • Scalable
    • Big plus
• Disavantages
  • Complex networking
  • Overhead
    • Databases
    • Servers

Docker

is an open platform for developers and sysadmins to build, ship, and run distributed applications, whether on laptops, data center VMs, or the cloud.

Definition

• Containers are a way to package software in a format that can run isolated on a shared operating system.
• Unlike VMs, containers do not bundle a full operating system - only libraries and setting required to make the software work are needed.
• This makes for efficientm, lightweight, self-contained systems and guarantees that software will always run the same, regardless of where it’s deployed.

Docker vs VM

• VM = App + Bins/Libs + guest OS
• Container = App + Bins/Libs + Docker

Dockerfile

• Describes the build process for an image
• Can be run to automatically create an image
• Contains all the commands necessary to build the image and run your application.

Kubernetes

Components

• Node
  • Kubelet
  • Communicates with master
  • Run Pods
• Pod
  • Runs 1+ containers
  • Exists on a node
• Service
  • Handles requests Usually a load balancer
• Deployment
  • Defines desired state - kubernetes handles the rest