talks/kubernetes_101/index.md

title	description	author	keywords
Kubernetes 101	An introduction	Ricardo Band	kubernetes,container,basics

Kubernetes 101

An introduction

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Stuff you should already know

• Containers
• Container engines
  • docker, podman ❤️
• Bonus points for:
  • docker-compose
  • podman-compose

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Agenda part 1 - The basics

• 🧑 Workloads aka your app
• 🛋️ Environment
• 📦 Containers
• 🏡 Pods
• 🏭 Deployments
• 🏪 Services
• 💾 Volumes
• 🌆 Namespaces

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Agenda part 2 - Advanced topics

• 🏷️ Labels and 🔖 Taints
• 🏘️ ReplicaSets
• 🧰 DaemonSet
• 🗃️ StatefulSets
• 🌐 Ingress Controller
• 📑 Cluster DNS
• 💾 Container Storage Interface (CSI)
• 🕸️ Container Network Interface (CNI)
  • 👮 Network Policies

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🧑🛋️ Workloads and their environment

Example: Simple PHP app

• index.php
• PHP runtime (php-fpm)
• Webserver (NGINX)
• OS (Alpine)

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📦 Containers

• Isolated environment
  • Linux namespace and cgroups
• Networking?
• Persistant storage?
• Scheduling, Load balancing

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🏡 Pods

• "Runnable unit of work"
• Holds Containers
• Connects to overlay network
• Container runtime interfaces (CRI)
  • containerd, CRI-O, Docker

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🏭 Deployment

• Manages:
  • Pods
  • Volumes
  • Secrets
• Types:
  • ReplicaSets
  • DaemonSets
  • StatefulSets

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🏪 Services

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💾 Volumes

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🌆 Namepaces

• Isolates group of resources
• Names need to be unique

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You survived, take a cookie!

🍪

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💣 Hands on

Let's deploy a simple web app with a volume.

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🏷️ Labels and 🔖 Taints

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🏘️ ReplicaSets

• Maintain a stable set of replica Pods
• Pods are identical
• Good for scaling
• Finds Pods by their label 🏷️

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🧰 DaemonSets

• Pods are started on every node of the cluster
• Useful for cluster wide services

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🗃️ StatefulSets

• Fine control over storage
• Pods are started in order
• Pods have stable identities
  • redis-1, redis-2, redis-3, ...
• Useful for clustered services
  • E.g. primary pod needs to start first

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🌐 Ingress Controller

• Load balancer
• Can be NGINX, HAProxy
• Different in Cloud kubernetes
• Handles HTTP(S) traffic to the cluster
• Kubernetes object: Ingress
• OpenShift object: Route

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📑 Cluster DNS

• Pods: <pod-ip-address>.<namespace-name>.pod.cluster.local
• Services: <service-name>.<namespace-name>.svc.cluster.local
• Pods behind Services: <pod-ip-address>.<service-name>.<namespace-name>.svc.cluster.local
• /etc/resolv.conf:

  nameserver 2001:cafe:42:1::23
  search <namespace>.svc.cluster.local svc.cluster.local cluster.local
  options ndots:5
  

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💾 Container Storage Interface (CSI)

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🕸️ Container Netrwork Interface (CNI)

👮 Network Policies

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Kubernetes distribution

• 💻 On bare metal
  • RedHat OpenShift
  • OKD
  • Rancher
  • k3s/k3os (RaspberryPi)
• ⛅ In the cloud:
  • Amazon (EKS, ECS)
  • Google (GCP)

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Still not enough?

• 🃏 Custom Resources
• 🔑 Secrets
• 📡 Control Plane
• 🔩 Operators
• 🕑 Jobs and CronJobs
• 🗺️ ConfigMaps
• 🔐 Pod Security Policies
• 🪪 Role Based Access Control (RBAC)
• 🪵 Resource Quotas

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Sources

• Kubernetes Children’s Guide

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by Ricardo Band

mailto:email@ricardo.band
 https://www.ricardo.band/