kubectl wip

kubernetes/kubectl/README.md

@@ -0,0 +1,157 @@
+# Introduction to KUBECTL
+
+To start off this tutorial, we will be using [kind](https://kind.sigs.k8s.io/) to create our test cluster. </br>
+You can use `minikube` or any Kubernetes cluster. </br>
+
+Kind is an amazing tool for running test clusters locally as it runs in a container which makes it lightweight and easy to run throw-away clusters for testing purposes. </br>
+
+## Create a kubernetes cluster
+
+```
+# create two clusters
+kind create cluster --name dev --image kindest/node:v1.23.5
+kind create cluster --name prod --image kindest/node:v1.23.5
+
+# see cluster up and running
+kubectl get nodes
+NAME                  STATUS   ROLES                  AGE     VERSION
+prod-control-plane   Ready    control-plane,master   2m12s   v1.23.5
+```
+
+# Understanding the KUBECONFIG
+
+Default location of the `kubeconfig` file is in `<users-directory>/.kube/config`
+
+```
+kind: Config
+apiVersion: v1
+clusters:
+ - list of clusters (addresses \ endpoints) 
+users:
+ - list of users (thing that identifies us when accessing a cluster [certificate]) 
+contexts:
+ - list of contexts ( which user and cluster to use when running commands)
+```
+
+Commands to interact with `kubeconfig` are `kubectl config`. </br>
+Key commands are telling `kubectl` which context to use 
+
+```
+kubectl config current-context
+kubectl config get-contexts
+kubectl config use-context <name>
+```
+
+You can also tell your `kubectl` to use different config files. </br>
+This is useful to keep your production config separate from your development ones </br>
+
+Set the `$KUBECONFIG` environment variable to a path:
+```
+#linux
+export KUBECONFIG=<path>
+
+#windows 
+$ENV:KUBECONFIG="C:\Users\aimve\.kube\config"
+```
+
+# Working with Kubernetes resources
+
+Now that we have cluster access, next we can read resources from the cluster
+with the `kubectl get` command.
+
+## Namespaces 
+
+Most kubernetes resources are namespace scoped:
+
+```
+kubectl get namespaces
+```
+
+By default, `kubectl` commands will run against the `default` namespace
+
+## List resources in a namespace
+
+```
+kubectl get <resource>
+
+kubectl get pods
+kubectl get deployments
+kubectl get services
+kubectl get configmaps
+kubectl get secrets
+kubectl get ingress
+```
+
+## KUBECTL Create resources
+
+We can create a namespace with the `kubectl create` command:
+
+```
+kubectl create ns example-apps
+```
+
+Let's create a couple of resources:
+
+```
+
+kubectl -n example-apps create deployment webserver --image=nginx --port=80
+kubectl -n example-apps get deploy
+kubectl -n example-apps get pods
+
+kubectl -n example-apps create service clusterip webserver --tcp 80:80
+kubectl -n example-apps get service
+kubectl -n example-apps port-forward svc/webserver 80
+# we can access http://localhost/
+
+kubectl -n example-apps create configmap webserver-config --from-file config.json=./kubernetes/kubectl/config.json
+kubectl -n example-apps get cm
+
+kubectl -n example-apps create secret generic webserver-secret --from-file secret.json=./kubernetes/kubectl/secret.json
+kubectl -n example-apps get secret
+
+```
+
+## Working with YAML
+
+As you can see we can create resources with `kubectl` but this is only for basic testing purposes.
+Kubernetes is a declarative platform, meaning we should provide it what to create instead
+of running imperative line-by-line commands. </br>
+
+We can also get the YAML of pre-existing objects in our cluster with the `-o yaml` flag on the `get` command </br>
+
+Let's output all our YAML to a `yaml` folder:
+
+```
+kubectl -n example-apps get cm webserver-config -o yaml > .\kubernetes\kubectl\yaml\config.yaml
+kubectl -n example-apps get secret webserver-secret -o yaml > .\kubernetes\kubectl\yaml\secret.yaml
+kubectl -n example-apps get deploy webserver -o yaml > .\kubernetes\kubectl\yaml\deployment.yaml
+kubectl -n example-apps get svc webserver -o yaml > .\kubernetes\kubectl\yaml\service.yaml   
+```
+
+## Create resources from YAML files
+
+The most common and recommended way to create resources in Kubernetes is with the `kubectl apply` command. </br>
+This command takes in declarative `YAML` files.
+
+To show you how powerful it is, instead of creating things line-by-line, we can deploy all our infrastructure
+with a single command. </br>
+
+Let's deploy a Wordpress CMS site, with a back end MySQL database. </br>
+This is a snippet taken from my `How to learn Kubernetes` video:
+
+```
+kubectl create ns wordpress-site
+kubectl -n wordpress-site apply -f ./kubernetes/tutorials/basics/yaml/
+```
+
+We can checkout our site with the `port-forward` command:
+
+```
+kubectl -n wordpress-site get svc
+
+NAME        TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
+mysql       ClusterIP   10.96.146.75   <none>        3306/TCP   17s
+wordpress   ClusterIP   10.96.157.6    <none>        80/TCP     17s
+
+kubectl -n wordpress-site port-forward svc/wordpress 80
+```