kubernetes

#Installing kubenetes

-- https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

#Debian

-- You can easily install kubernetes using MINIKUBE

-- wget https://storage.googleapis.com/minikube/releases/latest/minikube-linux-amd64
-- chmod +x minikube-linux-amd64
-- sudo mv minikube-linux-amd64 /usr/local/bin/minikube
-- sudo apt install conntrack
#setup
-- minikube start --driver=none (this will create a ~/.kube/config file with requesite certificates)
-- kubectl apply -f config-secret.yml 
#alternatively 

-- sudo apt-get update && sudo apt-get install -y apt-transport-https curl
-- curl -s https://packages.cloud.google.com/apt/doc/apt-key.gpg | sudo apt-key add -
-- cat <<EOF | sudo tee /etc/apt/sources.list.d/kubernetes.list
    deb https://apt.kubernetes.io/ kubernetes-xenial main
    EOF
-- sudo apt-get update
-- sudo apt-get install -y kubelet kubeadm kubectl
-- sudo apt-mark hold kubelet kubeadm kubectl

#Getting all the info in the kubenetes infra
-- kubectl get all

#setting up environment
-- ensure the secret file is created first
-- kubectl apply -f config_with_secret.yml
-- kubectl get secret (ensure it is there)

#secondly

-- ensure to create any config maps 
-- kubectl apply -f configmap.yml



#Service

-- You can create the Service config file in the same file as the Deployment confifs
-- if done as above

RUN

-- kubectl apply -f mango.yml
-- kubectl get service

#To check if the service is connected to the right pod
-- kubectl describe service {service_name}
-- kubectl get pod -o wide
-- check for the 'EndPoints' IP and port match the output of 'get pod -o wide' IP

#ConfigMaps
-- These are files used to keep track of addresses of shared resources e.g. IP addresses for database servers which multiple services rely on

#Creating a service to be accessible in the public WAN

---

apiVersion: v1
kind: Service
metadata:
    name: mongo-express-service
spec:
    selector:
      app: mongo-express
    type: LoadBalancer
    ports:
      - protocol: TCP
        port: 8081
        targetPort: 8081
        nodePort: 30000

The type load balancer: means that the service will be given both an internal and external IP from which it can be accessible on the browser

** ClusterIP ** this is an internal IP each service is given but can only be used within the pod

#Accessing a pod
-- kubectl exec -it {pod_id} -- /bin/sh