Kubernetes Namespaces - ResourceQuota - Declarative using YAML ¶

Kubernetes Manifests ¶

00

#00-namespace-LimitRange-default.yml
apiVersion: v1
kind: Namespace
metadata: 
  name: dev3
---  
apiVersion: v1
kind: LimitRange
metadata:
  name: default-cpu-mem-limit-range
  namespace: dev3
spec:
  limits:
    - default:
        cpu: "500m"  # If not specified default limit is 1 vCPU per container     
        memory: "512Mi" # If not specified the Container's memory limit is set to 512Mi, which is the default memory limit for the namespace.
      defaultRequest:
        cpu: "300m" # If not specified default it will take from whatever specified in limits.default.cpu      
        memory: "256Mi" # If not specified default it will take from whatever specified in limits.default.memory
      type: Container 
---
apiVersion: v1
kind: ResourceQuota
metadata:
  name: ns-resource-quota
  namespace: dev3
spec:
  hard:
    requests.cpu: "1"
    requests.memory: 1Gi
    limits.cpu: "2"
    limits.memory: 2Gi  
    pods: "5"    
    configmaps: "5" 
    persistentvolumeclaims: "5" 
    secrets: "5" 
    services: "5"

01

#01-storage-class.yml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata: 
  name: ebs-sc
provisioner: ebs.csi.aws.com
volumeBindingMode: WaitForFirstConsumer

02

#02-persistent-volume-claim.yml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: ebs-mysql-pv-claim
  namespace: dev3  
spec: 
  accessModes:
    - ReadWriteOnce
  storageClassName: ebs-sc
  resources: 
    requests:
      storage: 4Gi

03

#03-UserManagement-ConfigMap.yml
apiVersion: v1
kind: ConfigMap
metadata:
  name: usermanagement-dbcreation-script
  namespace: dev3
data: 
  mysql_usermgmt.sql: |-
    DROP DATABASE IF EXISTS usermgmt;
    CREATE DATABASE usermgmt;

04

#04-mysql-deployment.yml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: mysql
  namespace: dev3
spec: 
  replicas: 1
  selector:
    matchLabels:
      app: mysql
  strategy:
    type: Recreate 
  template: 
    metadata: 
      labels: 
        app: mysql
    spec: 
      containers:
        - name: mysql
          image: mysql:5.6
          env:
            - name: MYSQL_ROOT_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-db-password
                  key: db-password 
          ports:
            - containerPort: 3306
              name: mysql    
          volumeMounts:
            - name: mysql-persistent-storage
              mountPath: /var/lib/mysql    
            - name: usermanagement-dbcreation-script
              mountPath: /docker-entrypoint-initdb.d #https://hub.docker.com/_/mysql Refer Initializing a fresh instance                                            
      volumes: 
        - name: mysql-persistent-storage
          persistentVolumeClaim:
            claimName: ebs-mysql-pv-claim
        - name: usermanagement-dbcreation-script
          configMap:
            name: usermanagement-dbcreation-script

05

#05-mysql-clusterip-service.yml
apiVersion: v1
kind: Service
metadata: 
  name: mysql
  namespace: dev3
spec:
  selector:
    app: mysql 
  ports: 
    - port: 3306  
  clusterIP: None # This means we are going to use Pod IP

06

#06-UserManagementMicroservice-Deployment-Service.yml
apiVersion: apps/v1
kind: Deployment 
metadata:
  name: usermgmt-microservice
  namespace: dev3
  labels:
    app: usermgmt-restapp
spec:
  replicas: 1
  selector:
    matchLabels:
      app: usermgmt-restapp
  template:  
    metadata:
      labels: 
        app: usermgmt-restapp
    spec:
      initContainers:
        - name: init-db
          image: busybox:1.31
          command: ['sh', '-c', 'echo -e "Checking for the availability of MySQL Server deployment"; while ! nc -z mysql 3306; do sleep 1; printf "-"; done; echo -e "  >> MySQL DB Server has started";']      
      containers:
        - name: usermgmt-restapp
          image: stacksimplify/kube-usermanagement-microservice:1.0.0
          ports: 
            - containerPort: 8095           
          env:
            - name: DB_HOSTNAME
              value: "mysql"            
            - name: DB_PORT
              value: "3306"            
            - name: DB_NAME
              value: "usermgmt"            
            - name: DB_USERNAME
              value: "root"            
            - name: DB_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: mysql-db-password
                  key: db-password           
          livenessProbe:
            exec:
              command: 
                - /bin/sh
                - -c 
                - nc -z localhost 8095
            initialDelaySeconds: 60
            periodSeconds: 10
          readinessProbe:
            httpGet:
              path: /usermgmt/health-status
              port: 8095
            initialDelaySeconds: 60
            periodSeconds: 10

07

#07-UserManagement-Service.yml
apiVersion: v1
kind: Service
metadata:
  name: usermgmt-restapp-service
  namespace: dev3
  labels: 
    app: usermgmt-restapp
spec:
  type: NodePort
  selector:
    app: usermgmt-restapp
  ports: 
    - port: 8095
      targetPort: 8095
      nodePort: 31231

08

#08-kubernetes-secrets.yml
apiVersion: v1
kind: Secret
metadata:
  name: mysql-db-password
  namespace: dev3
type: Opaque
data: 
  db-password: ZGJwYXNzd29yZDEx

Step-01: Create Namespace manifest ¶

Important Note: File name starts with 00- so that when creating k8s objects namespace will get created first so it don't throw an error.
```
apiVersion: v1
kind: Namespace
metadata:
  name: dev3
```

Step-02: Create ResourceQuota manifest ¶

apiVersion: v1
kind: ResourceQuota
metadata:
  name: ns-resource-quota
  namespace: dev3
spec:
  hard:
    requests.cpu: "1"
    requests.memory: 1Gi
    limits.cpu: "2"
    limits.memory: 2Gi  
    pods: "5"    
    configmaps: "5" 
    persistentvolumeclaims: "5" 
    replicationcontrollers: "5" 
    secrets: "5" 
    services: "5"

Step-03: Create k8s objects & Test ¶

# Create All Objects
kubectl apply -f kube-manifests/

# List Pods
kubectl get pods -n dev3 -w

# View Pod Specification (CPU & Memory)
kubectl get pod <pod-name> -o yaml -n dev3

# Get & Describe Limits
kubectl get limits -n dev3
kubectl describe limits default-cpu-mem-limit-range -n dev3

# Get Resource Quota 
kubectl get quota -n dev3
kubectl describe quota ns-resource-quota -n dev3

# Get NodePort
kubectl get svc -n dev3

# Get Public IP of a Worker Node
kubectl get nodes -o wide

# Access Application Health Status Page
http://<WorkerNode-Public-IP>:<NodePort>/usermgmt/health-status

AWS EKS - Elastic Kubernetes Service - Masterclass ¶

Step-04: Clean-Up ¶

Delete all k8s objects created as part of this section
```
# Delete All
kubectl delete -f kube-manifests/
```

References: ¶

https://kubernetes.io/docs/tasks/administer-cluster/namespaces-walkthrough/
https://kubernetes.io/docs/tasks/administer-cluster/manage-resources/quota-memory-cpu-namespace/

Additional References: ¶

https://kubernetes.io/docs/tasks/administer-cluster/manage-resources/cpu-constraint-namespace/
https://kubernetes.io/docs/tasks/administer-cluster/manage-resources/memory-constraint-namespace/