Merge pull request #53 from josephlewis42/jl/feat/kubernetes

Added review for Kubernetes Skill Tree

Kubernetes Skill Tree/CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
+## Peer Review 1 [Unreleased]
+
+### Added
+
+* More steps to create familiarity with commonly used parts of the sprawling `kubectl` command.
+* Steps to bringing your own application to Kubernetes:
+    * "Use an image from a private container repository"
+    * "Create a container from your app"
+* Introduction to additional tools:
+    * "Try an alternative to kubectl like K9s"
+    * "Install the Kubernetes Dashboard"
+* Milestones for beginner/intermediate/advanced use cases:
+    * Beginner: "Deploy apps for your personal use"
+    * Intermediate: "Run apps for a club on a cluster"
+    * Advanced: "Host apps on the Internet from your cluster"
+* Places to get more information:
+    * "Explore kubectl's "Troubleshooting" section"
+    * "Explore the Kubernetes Reference Guide"
+    * "Explore the Kubernetes Tutorials"
+* More gradual exposure to different concepts:
+    * "Set up health check probes on your workloads" for the different kinds of health checks
+    * "Set up two workloads that communicate" for in-cluster DNS
+    * "Deploy a stateless app" the first major step after a Hello, World Pod is deploying 
+      something that doesn't need to store data.
+    * "Expose a Deployment using a Service" step to show that Deployments and Pods work similarly.
+    * "Create a multi-container Pod" for sidecars
+    * "Use headless Services for service discovery" for service discovery
+    * "Deploy a non-HTTP workload e.g. FTP server" for TCP networking, which is more primitive
+    * "Optimize your workload container sizes" for cost savings and performance
+    * "Set up ServiceAccounts for your workloads" for security and cluster sharing
+    * "Share your cluster with a second person" for practical RBAC
+    * "Configure a Deployment for high availability updates" for proper use of Deployments
+* Different options to get Kubernetes clusters:
+    * "Deploy a cluster in the cloud" this is what most people do.
+    * "Set up a cluster from scratch on Raspberry Pis" a common approach for hobbyists with lots of info and
+      varying degrees of difficulty depending on how deep into it you want to go.
+* Basic operations needs:
+    * Learn how to backup and restore your cluster
+    * Make your cluster reproducible with Terraform
+
+### Changed
+
+* "Create a basic Pod" to "Deploy a 'Hello, World!'' Pod" because it's not obvious what "basic" means.
+* "Secure sensitive data with Secrets" to "Use a Secret to distribute credentials" because Secrets don't
+  provide much security.
+* Merged "Set resource requests for Pods" and "Set resource limits for Pods" to 
+  "Set resource requests and limits for workloads" because it's the same topic.
+* "Perform rolling updates and rollbacks" to "Roll back a change to a Deployment" rolling updates are the default, 
+  but being able to undo a mistake is very important.
+* Merged "Control Pod scheduling tolerations" and "Configure Pod affinity and anti-affinity" into 
+  "Control scheduling with tolerations and affinity" because they're similar topics.
+* Replaced "Set up Persistent Volumes and Claims" and "Create StatefulSets for stateful applications" with "
+  Deploy Wordpress and MySQL with Persistent Volumes" to focus on an outcome. This wil point you at the Kubernetes.io 
+  tutorial for stateful workloads.
+* Consolidated topics related to operators and CRDs into: "Develop your own operator and CRDs". This is a niche skill,
+  but it's good to know it's possible.
+* Consolidated multiple service mesh/advanced networking related solutions to "Deploy a service mesh to your cluster"
+* Consolidated multiple monitoring items to: "Set up cluster-wide logging and monitoring" and 
+  "Set up alerting for unhealthy workloads". Logging/monitoring are usually the same tool and useful by themselves.
+* Many small wording changes to improve cohesion.
+
+### Removed
+
+* "Use Kubectl to manage resources" because it has high overlap with the other skills.
+* Duplicate "Expose a Pod using a Service"
+* "Apply network policies to control traffic between Pods" because only some configurations support this out of the box,
+  it silently fails otherwise which would be frustrating for a beginner.
+* Skills that focus on specific parts of deploying your own cluster, these align better with a platform engineer role 
+  than a hobbyist. Some of these are now covered by deploying a cluster on a Raspberry Pi:
+    * "Set up a container runtime e.g. Containerd, CRI-0" 
+    * "Set up ingress for external access e.g. NGINX, Traefik"
+    * "Set up a multi-node cluster with kubeadm"
+    * "Set up a cluster using Kubeadm"
+    * "Use Cluster API"
+    * "Use Kubernetes on Bare Metal"
+    * "Use persistent volume provisioners"
+    * "Install and configure a networking solution e.g. Calico, Flannel"
+* Removed multiple items related to storage, these should be covered enough to get by with the stateful application tile:
+    * "Use external storage solutions with Kubernetes"
+    * "Configure storage class"
+    * "Implement storage solutions with CSI drivers"
+* Removed multiple skills that start to matter when you have lots of people or large clusters:
+    * "Optimize costs within Kubernetes" partially covered by optimizing workloads
+    * "Use OPA for policies"
+    * "Perform cluster performance tuning" 
+    * "Implement GitOps practices" partially covered elsewhere
+    * "Create a blue-green deployment" not best practice in Kubernetes
+    * "Create a canary deployment" already covered with Deployments
+
+### Fixed
+
+* Various capitalization issues.
+    * `Kind` to `kind` to match their website
+    * `MiniKube` to `minikube` to match their website
+    * Capitalized Kubernetes types except namespace to be consistent with kubernetes.io