Kubernetes Basics Workshop

Benefits of containers

• Portable
• Cloud deployable
• Scalable (Scale-in and Scale-out)
• Declarative format
• Good for microservices

Challenge: Managing many containers in several servers

What is Kubernetes?

• Container orchestration system
  • Deploying
  • Scaling
  • Networking
  • Storage
  • Security
  • Monitoring
  • Logging
  • Automatic cluster resource management

kubectl

• CLI tool for Kubernetes
• ~/.kube/conifg file stores cluster address and credentials
• Kubernetes context: Cluster, namespace, user

Imperative vs. Declarative

• Imperative: Directly instruct Kubernetes to perform actions.
• Declarative: Define desired state in a config file; Kubernetes ensures current state matches it.

Imperative Example

# Imperative command to create a pod
kubectl run my-pod --image=nginx

Declarative Example

To create a pod declaratively, you define the pod in a YAML file and then apply it:

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: nginx
    image: nginx

Apply the configuration using kubectl apply:

# Declarative command to create a pod
kubectl apply -f pod.yaml

Core Kubernetes Components

• Kubernetes API Server: Manages and validates requests.
• ETCD: Stores all cluster data.
• Controller Manager: Handles control loops.
• Scheduler: Assigns pods to nodes.
• Kubelet: Runs on nodes to manage pods.
• Kube Proxy: Handles network routing.

Helm

• Kubernetes package manager
• ArtifactHub.io: A public helm chart repository.
• Install/uninstall/upgrade helm charts

Pod

• Smallest unit in Kubernetes
• Includes one or more containers
• Containers share network and storage
• Containers in a pod are scheduled on the same node

Pod Example

Declarative

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: nginx
    image: nginx

Imperative

# Imperative command to create a pod
kubectl run my-pod --image=nginx

Deployment

• Manages pods
• Ensures desired state
• Can scale pods

Deployment Example

Declarative

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx

Imperative

# Imperative command to create a deployment
kubectl create deployment my-deployment --image=nginx

Service

• Exposes pods to the network
• Load balances traffic
• Types: ClusterIP, NodePort, LoadBalancer, ExternalName

Service Example

Declarative

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: nginx
  ports:
  - protocol: TCP
    port: 80
    targetPort: 80
  type: ClusterIP

Imperative

# Imperative command to create a service
kubectl expose deployment my-deployment --type=ClusterIP --port=80 --target-port=80

ConfigMap

• Stores configuration data
• Decouples configuration from pods
• Can be updated without restarting pods

ConfigMap Example

Declarative

apiVersion: v1
kind: ConfigMap
metadata:
  name: my-config
data:
  key: value

Imperative

# Imperative command to create a configmap
kubectl create configmap my-config --from-literal=key=value

Secret

• Stores sensitive data
• Encoded in base64
• Decouples secrets from pods

Secret Example

Declarative

apiVersion: v1
kind: Secret
metadata:
  name: my-secret
type: Opaque
data:
  username: dXNlcm5hbWU=
  password: cGFzc3dvcmQ=

Imperative

# Imperative command to create a secret
kubectl create secret generic my-secret --from-literal=username=admin --from-literal=password=secretpass

Workload kinds in Kubernetes

• Pod
• Deployment
• StatefulSet
• DaemonSet
• Job
• CronJob

Namespace

• Logical partition of a cluster
• Used to divide resources
• Unique names within a namespace

kuberise.io

• An open-source Internal Developer Platform for Kubernetes
• GitOps-based deployment with ArgoCD
• DRY (Don't Repeat Yourself) approach
  • Same templates for all environments
  • Different values for each environment
• ArgoCD app of apps pattern
• Enable or disable platform tools
• Add your developer applications
• Single templates folder
• Values folder for each platform

./scripts/install.sh minikube onprem https://github.com/kuberise/kuberise.io.git main onprem.kuberise.dev

Kuberise dashboards

• ArgoCD
• Grafana
• Keycloak (Single Sign-On)
• Sample Developer Applications

k9s

• k9s is a Terminal-based UI for Kubernetes
• namespaces
• pods
• deployments
• services
• secrets
• configmaps
• ingress