101 Docker & k8s

Docker

• Containerization Fundamentals

  • LXC: It implements process sandboxing. https://linuxcontainers.org/
  • Process group isolation
  • AUFS: https://en.wikipedia.org/wiki/Aufs
  • https://medium.com/@jessgreb01/digging-into-docker-layers-c22f948ed612
  • OverlayFS as a successor to AUFS. https://docs.docker.com/storage/storagedriver/overlayfs-driver/
  • Docker originally used LinuX Containers (LXC), but later switched to runC (formerly known as libcontainer), which runs in the same operating system as its host. This allows it to share a lot of the host operating system resources. Also, it uses a layered filesystem (AuFS) and manages networking.
  • Docker is diferent to a VM: https://stackoverflow.com/questions/16047306/how-is-docker-different-from-a-virtual-machine
  • Docker vs automation systems like chef or puppet or https://www.vagrantup.com/

• What is a container and an image

  • Portable deployment across machines. Docker defines a format for bundling an application and all its dependencies into a single object called a container.

• Container Images.

  • CMD vs Entrypoint: https://medium.freecodecamp.org/docker-entrypoint-cmd-dockerfile-best-practices-abc591c30e21

• Create your image. Dockerfile basics

  • Docker commands build, run, push, pull

• Docker volumes

• Docker compose and docker-compose.yaml syntax

  • Compose with other data
  • https://docs.docker.com/compose/startup-order/

• Secrets

• Docker registry to hold images

Docker Exercise: Create a Docker Image and link it with services

Description: Create your docker image for a simple site writen in node.js. Required: We need a redis service and a mongodb database to complete the service.

Tasks

1. BASIC: Create a docker image from the provided node.js code and upload it to public DockerHub registry.
2. ADVANCED: Write a docker-compose.yaml file that attatches a mongodb database to the host.
3. PRO: Modify the docker-compose.yaml to add redis support and ensure we have valid data on redis before start.
   • Side Note: you will need to create a custom redis image that starts FROM redis and populates it with data.
   • Redis autocomplete idea: https://redislabs.com/ebook/part-2-core-concepts/chapter-6-application-components-in-redis/6-1-autocomplete/6-1-2-address-book-autocomplete/

K8s

• K8s architecture and fundamentals

• Minikube - https://kubernetes.io/docs/setup/minikube/#installation

  • https://stackoverflow.com/questions/45002364/how-to-upgrade-minikube
  • Dashboard
  • Minikube own registry
    • minikube start
    • minikube dashboard
    • minikube addons enable registry
  • Other registry providers: Amazon ECR, https://aws.amazon.com/ecr/

• Pods, Deployments and Services

• The kubectl cli

• Deploy your Dockerfile in k8s

• ConfigMap

• K8s, apply change when configmap changes, reactive changes

• Cloud Managed k8s solutions. Example with digitalocean

• Auto deploy with bitbucket pipelines

• Extra: Metrics with Prometheus and Graphana

Who to follow

• https://www.cncf.io/
• https://www.hashicorp.com/
• https://cloud.google.com/knative/
• https://kubernetes.io/
• https://www.terraform.io/

Other interesting things

• EFK Stack to monitor kubernetes logs. minikube addons enable efk
• https://github.com/jetstack/cert-manager