Kubernetes Study

Overview

Kubernetes project that will provide an environment with an accessible Web-based MongoDB admin interface and an instance of the Mongo database.

┌──────────────────┐
│   Mongo Express  │
│ External Service │
└────────┬─────────┘
         │
         │
    ┌────▼────┐
    │  Mongo  │          ┌────────────────┐       ┌───────┐
    │ Express ├─────────►│MongoDb Internal├──────►│MongoDb│
    │   Pod   │          │    Service     │       │  Pod  │
    └─▲─────▲─┘          └────────────────┘       └─▲───▲─┘
      │     │                                       │   │
      │     │                                       │   │
      │     │                                       │   │
      │     │                             ┌───────┐ │   │
      │     └─────────────────────────────┤Secrets├─┘   │
      │                                   └───────┘     │
      │                                                 │
      │                                  ┌─────────┐    │
      └──────────────────────────────────┤ConfigMap├────┘
                                         └─────────┘

Requirements

• Docker
• Kubectl
• Minikube

Instructions

Run the below commands

kubectl apply -f mongo-secret.yaml
kubectl apply -f mongo.yaml
kubectl apply -f mongo-configmap.yaml 
kubectl apply -f mongo-express.yaml

// Check if the resources were created successfully
kubectl get all

// Apply an ip for the external service
minikube service mongo-express-service

// Access the desired service ip from the browser
minikube service --all

Basic commands

Encode base64 using terminal

echo -n 'value' | base64

Create minikube cluster

minikube start
kubectl get nodes
minikube status
kubectl version

kubectl commands

kubectl get all
kubectl get all | grep mongodb
kubectl get nodes
kubectl get pod
kubectl get pod -o wide
kubectl get services
kubectl create deployment mongo-deployment --image=mongo
kubectl get deployment
kubectl get replicaset
kubectl edit deployment mongo-deployment

Debugging

kubectl logs {pod-name}
kubectl exec -it {pod-name} -- bin/bash

Create mongo deployment

kubectl create deployment mongo-deployment --image=mongo
kubectl logs mongo-deployment-{pod-name}
kubectl describe pod mongo-deployment-{pod-name}

Delete deployment

kubectl delete deployment mongo-depl

Create or edit config file

vim mongo-deployment.yaml
kubectl apply -f mongo-deployment.yaml
kubectl get pod
kubectl get deployment

Delete with config

kubectl delete -f mongo-deployment.yaml

Get metrics

kubectl top

The top command returns the current CPU and memory usage for a cluster’s pods or nodes, or for a particular pod or node if specified.

Exposing an external service using minikube

minikube service mongo-express-service
minikube service --all