Introduction
In this article, we will cover various Kubernetes commands and configurations, as well as their usage within Amazon EKS (Elastic Kubernetes Service). Kubernetes is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications. EKS is a managed Kubernetes service provided by AWS, making it easier to run Kubernetes without needing to maintain the control plane yourself.
Basic Kubernetes Commands
Deploying an Application
To deploy an application in Kubernetes, you typically start with a deployment YAML file (my-deployment.yaml). This file defines the desired state of your application, including the number of replicas, the container image to use, and other configurations.
sudo kubectl create -f my-deployment.yamlThis command creates the deployment as specified in the YAML file. The -f flag specifies the file to use.
sudo kubectl rollout status deployment/my-deploymentThis command checks the status of the deployment rollout, ensuring that all replicas are up and running.
sudo kubectl rollout history deployment/my-deploymentThis command shows the revision history of the deployment, which is useful for tracking changes and debugging issues.
sudo kubectl delete deployment my-deploymentThis command deletes the specified deployment, removing all associated resources.
Recording Deployment Details
To keep a history of the changes made to a deployment, you can use the --record flag.
sudo kubectl create -f my-deployment.yaml --recordThis command creates the deployment and records the current command in the resource’s annotation.
Applying Changes to a Deployment
sudo kubectl apply -f my-deployment.yamlThis command updates an existing deployment to match the configuration in the YAML file. If the deployment does not exist, it will be created.
sudo kubectl describe deploymentThis command provides detailed information about the deployment, including the current state of the replicas, events, and more.
sudo kubectl get nodesThis command lists all nodes in the Kubernetes cluster, providing their status and other details.
Updating a Deployment
sudo kubectl set image deployment/my-deployment nginx-container=nginx:1.12This command updates the container image used in the deployment to a new version.
Rolling Back a Deployment
sudo kubectl rollout undo deployment/my-deploymentThis command rolls back the deployment to a previous revision.
Viewing Pods and Deployments
sudo kubectl get deploymentThis command lists all deployments in the current namespace.
sudo kubectl get podsThis command lists all pods in the current namespace.
EKS Cluster Configuration
Basic Cluster Configuration
The following is a basic EKS cluster configuration YAML (cluster.yaml):
apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig
metadata:
name: eks-cluster
region: us-east-2
nodeGroups:
- name: ng-1
instanceType: t2.small
desiredCapacity: 3
ssh:
publicKeyName: eks-key
- name: ng-mixed
minSize: 3
maxSize: 5
instancesDistribution:
maxPrice: 0.2
instanceTypes: ["t2.small", "t3.small"]
onDemandBaseCapacity: 0
onDemandPercentageAboveBaseCapacity: 50
ssh:
publicKeyName: eks-keyAdvanced Cluster Configuration
A more advanced EKS cluster configuration might look like this:
apiVersion: eksctl.io/v1alpha5
kind: ClusterConfig
metadata:
name: eks-cluster
region: us-east-2
nodeGroups:
- name: scale-east2a
instanceType: t2.small
desiredCapacity: 1
maxSize: 10
availabilityZones: ["us-east-2a"]
iam:
withAddonPolicies:
autoScaler: true
labels:
nodegroup-type: stateful-east2a
instance-type: onDemand
ssh:
publicKeyName: eks-key
- name: scale-east2b
instanceType: t2.small
desiredCapacity: 1
maxSize: 10
availabilityZones: ["us-east-2b"]
iam:
withAddonPolicies:
autoScaler: true
labels:
nodegroup-type: stateful-east2b
instance-type: onDemand
ssh:
publicKeyName: eks-key
- name: scale-spot
desiredCapacity: 1
maxSize: 10
instancesDistribution:
instanceTypes: ["t2.small", "t3.small"]
onDemandBaseCapacity: 0
onDemandPercentageAboveBaseCapacity: 0
availabilityZones: ["us-east-2a", "us-east-2b"]
iam:
withAddonPolicies:
autoScaler: true
labels:
nodegroup-type: stateless-workload
instance-type: spot
ssh:
publicKeyName: eks-key
availabilityZones: ["us-east-2a", "us-east-2b"]
cloudWatch:
clusterLogging:
enableTypes: ["api", "audit", "authenticator"]Deployment Configuration Example
Here is an example deployment YAML file (deployment.yaml) for Kubernetes:
apiVersion: apps/v1
kind: Deployment
metadata:
name: test-autoscaler
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
service: nginx
app: nginx
spec:
containers:
- image: nginx
name: test-autoscaler
resources:
limits:
cpu: 300m
memory: 512Mi
requests:
cpu: 300m
memory: 512Mi
nodeSelector:
instance-type: spotRole-Based Access Control (RBAC) Configuration
RBAC in Kubernetes allows you to control who can access your cluster and what actions they can perform. Here is an example Role YAML file (role.yaml):
kind: Role
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
namespace: production
name: prod-viewer-role
rules:
- apiGroups: ["", "extensions", "apps"]
resources: ["*"] # can be further limited, e.g. ["deployments", "replicasets", "pods"]
verbs: ["get", "list", "watch"]And here is the corresponding RoleBinding YAML file (rolebinding.yaml):
kind: RoleBinding
apiVersion: rbac.authorization.k8s.io/v1beta1
metadata:
name: prod-viewer-binding
namespace: production
subjects:
- kind: User
name: testproduser
apiGroup: ""
roleRef:
kind: Role
name: testproduser-role
apiGroup: ""Conclusion
In this guide, we have covered basic Kubernetes commands for managing deployments, updating images, rolling back deployments, and viewing resources. We also explored how to configure an EKS cluster and set up Role-Based Access Control (RBAC) to secure your cluster. By understanding these concepts and commands, you will be well-equipped to manage and maintain Kubernetes clusters in a production environment.
