Improved Kubernetes cluster documentation

kubernetes-example/kubectl-intro.md

 # Introduction to kubectl 
 
+## Prerequisites
+
+For using this you must install the following tools: 
+
+- Python 
+- Pip
+- Kubectl 
+- Openstack-Client
+
+### Python 
+
+Install python and pip for your OS, if it is not installed. This is already done at the NetLab PCs.
+
+### Installing kubectl and arkade
+
+Run this in a **bash** terminal to download arkade and install kubectl:
+
+For windows you can use e.g. the **Git Bash** terminal.
+
+```bash
+curl -sLS https://dl.get-arkade.dev | sh
+arkade get kubectl
+# To load the path to the binary
+export PATH=$PATH:$HOME/.arkade/bin/
+```
+
+With arkade you can also install other tools: ```arkade get``` to see all possibilities.
+
+### Openstack Client
+
+To install the Openstack client and the magnum package:
+
+If you are using Windows, you must start the bash terminal with **Administrator** privileges!
+
+```bash
+pip3 install openstackclient python-magnumclient
+# Download the Openstack RC File from your Openstack account
+# Load the file
+source {USERNAME}-openrc.sh
+```
+
+### Download the kubeconfig 
+
+Download the kubeconfig file for your cluster from OpenStack.
+
+```bash
+# Before using this, check if Openstack RC File is loaded!
+openstack coe cluster config {CLUSTER_NAME}
+# Then run the given command in terminal
+export ...
+# Now you are able to run kubectl commands at your Kubernetes cluster
+```
+
 ## Deployment of the needed description in kubernetes
 
-These are two approaches to create the description in Kuberentes: 
+These are two approaches to create the description in Kubernetes: 
 
 ```bash
 # create a namespace 
@@ -41,10 +94,10 @@ kubectl logs -n web-test deployment/nginx-deployment
 
 ```bash
 # scale up instances to 5
-kubectl scale deployment/nginx-deployment --replicas=5
+kubectl scale -n web-test deployment/nginx-deployment --replicas=5
 
 # scale down instances again to 3
-kubectl scale deployment/nginx-deployment --replicas=3
+kubectl scale -n web-test deployment/nginx-deployment --replicas=3
 
 ```
 

kubernetes-example/nginx.yml

+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx-deployment
+  namespace: web-test
+spec:
+  selector:
+    matchLabels:
+      app: nginx-deployment
+  replicas: 3 # tells deployment to run 3 pods matching the template
+  template:
+    metadata:
+      labels:
+        app: nginx-deployment
+    spec:
+      containers:
+      - name: nginx
+        image: nginx:latest
+        ports:
+        - containerPort: 80
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kubernetes-example/service.yml

+apiVersion: v1
+kind: Service
+metadata:
+  name: nginx-service
+  namespace: web-test
+spec:
+  type: NodePort
+  selector:
+    app: nginx-deployment
+  ports:
+      # By default and for convenience, the `targetPort` is set to the same value as the `port` field.
+    - port: 80
+      targetPort: 80
+      # Optional field
+      # By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767)
+      nodePort: 30007
\ No newline at end of file