Linode Kubernetes Engine (LKE)
Linode Kubernetes Engine (LKE) is a fully-managed container orchestration service provided by Linode, allowing you to deploy and manage Kubernetes clusters effortlessly, without the hassle of setting up and maintaining the underlying infrastructure. This tutorial will guide you through the process of creating a Kubernetes cluster on LKE, accessing it, and deploying your first application.
By the end of this tutorial, you'll have a understanding of how to create, access, and manage Kubernetes clusters on Linode Kubernetes Engine.
Prerequisites
Before you begin, make sure you have the following:
Step 1: Create a Kubernetes Cluster
When creating a Kubernetes cluster on Linode Kubernetes Engine (LKE), you have several options and configurations to choose from. Here's a more detailed breakdown of the process:
1. Choose a Region
Linode has data centers located in multiple regions around the world. Select the region closest to your target audience or resources for better performance and lower latency.
2. Select Kubernetes Version
LKE supports multiple Kubernetes versions. Choose the version that best fits your requirements and application compatibility needs. It's generally recommended to use the latest stable version unless you have specific reasons to use an older version.
3. Configure Node Pool
A node pool is a group of compute instances (nodes) that run your Kubernetes workloads. You can configure the following settings for your node pool:
Node Type: Select the type of Linode instances you want to use as nodes in your cluster. Linode offers different instance types with varying CPU, RAM, and storage configurations. Choose the instance type that best suits your workload requirements.
Number of Nodes: Specify the initial number of nodes you want in your node pool. You can scale this number up or down later based on your application's resource needs.
Node Labels: Optionally, you can add labels to your nodes. Labels are key-value pairs that can be used to organize and select groups of nodes for scheduling specific workloads.
Node Taints: Taints allow you to mark nodes as unavailable for certain workloads unless those workloads explicitly tolerate the taint. This can be useful for dedicated nodes or special-purpose hardware.
Auto-scaling: Enable auto-scaling to automatically adjust the number of nodes in your node pool based on resource utilization. You can configure the minimum and maximum number of nodes, as well as the CPU and memory thresholds for scaling.
4. Add Additional Node Pools (Optional)
If you have different types of workloads or specific resource requirements, you can add multiple node pools to your cluster. Each node pool can have its own configuration for node type, labels, taints, and auto-scaling settings.
5. Configure Networking
LKE provides options for configuring the network settings for your cluster, including:
Cluster IP Range: Specify the IP address range to be used for internal cluster services.
Service IP Range: Define the IP address range for external-facing services.
Pod IP Range: Assign an IP address range for pods running in your cluster.
6. Add Addons (Optional)
LKE supports various addons that enhance the functionality of your Kubernetes cluster. Some popular addons include:
Linode Cloud Controller Manager: Integrates your Kubernetes cluster with Linode's cloud services, such as Load Balancers and Node Pools.
Helm: A package manager for Kubernetes that simplifies the deployment and management of applications.
Prometheus and Grafana: Tools for monitoring and visualizing your cluster's metrics and performance.
7. Review and Create Cluster
Once you've configured all the desired settings, review the cluster configuration and click "Create Cluster" to initiate the provisioning process.
After creating your cluster, LKE will provision the necessary compute resources and set up the Kubernetes control plane. This process may take several minutes to complete. Once the cluster is ready, you can proceed to accessing and managing it using the Linode CLI or the kubectl tool.
Step 2: Access Your Kubernetes Cluster
Accessing your Kubernetes cluster on Linode Kubernetes Engine (LKE) is a crucial step after creating the cluster. There are two primary ways to access your LKE cluster: using the Linode CLI or using the Kubernetes CLI (kubectl).
Using the Linode CLI
The Linode CLI is a command-line tool that allows you to interact with various Linode services, including LKE. Here's a more detailed explanation of the steps involved:
1. List Your Kubernetes Clusters
Run the following command to list all the Kubernetes clusters in your Linode account:
linode-cli lke cluster-list
This will display a list of your clusters, along with their IDs, names, regions, and other details.
2. Get the Kubeconfig File
The kubeconfig file is a configuration file that contains information about your Kubernetes cluster, including the API server address, cluster credentials, and other settings. You need this file to authenticate and communicate with your cluster using kubectl.
Run the following command to get the kubeconfig file for your cluster, replacing <cluster-id> with the ID of your cluster:
linode-cli lke kubeconfig-view <cluster-id>
This will print the kubeconfig file content to your terminal.
3. Save the Kubeconfig File
You can save the kubeconfig file output to a local file, e.g., kubeconfig.yaml:
linode-cli lke kubeconfig-view <cluster-id> > kubeconfig.yaml
4. Set the KUBECONFIG Environment Variable
To use the kubectl CLI with your LKE cluster, you need to set the KUBECONFIG environment variable to point to your kubeconfig file:
export KUBECONFIG=path/to/kubeconfig.yaml
You can also add this line to your shell configuration file (e.g., .bashrc, .zshrc) to make it persistent across terminal sessions.
Using kubectl
The kubectl CLI is the standard tool for managing Kubernetes clusters. Once you have the kubeconfig file, you can use kubectl to interact with your LKE cluster. Here are the steps:
1. Install kubectl
If you haven't already, install the kubectl CLI on your local machine. You can find installation instructions for various platforms in the official Kubernetes documentation: https://kubernetes.io/docs/tasks/tools/.
2. Get the Kubeconfig File
Follow the steps above to get the kubeconfig file for your LKE cluster using the Linode CLI:
linode-cli lke kubeconfig-view <cluster-id> > kubeconfig.yaml
3. Set the KUBECONFIG Environment Variable
Set the KUBECONFIG environment variable to point to your kubeconfig file:
export KUBECONFIG=path/to/kubeconfig.yaml
4. Use kubectl Commands
You should now be able to run kubectl commands against your LKE cluster. For example, to list all pods in your cluster:
kubectl get pods --all-namespaces
Or to get information about nodes in your cluster:
kubectl get nodes
You can explore various kubectl commands and manage your Kubernetes resources, such as deployments, services, and more, directly from your local machine.
Using the Linode CLI
1. Open a terminal on your local machine.
2. Run the following command to list your Kubernetes clusters:
linode-cli lke cluster-list
3. Copy the ID of your newly created cluster.
4. Run the following command to get the kubeconfig file for your cluster:
linode-cli lke kubeconfig-view <cluster-id>
5. This will print the kubeconfig file to your terminal. You can save it to a file (e.g., kubeconfig.yaml) and set the KUBECONFIG environment variable to point to this file.
export KUBECONFIG=path/to/kubeconfig.yaml
Using kubectl
1. Install the kubectl CLI on your local machine if you haven't already.
2. Run the following command to get the kubeconfig file for your cluster:
linode-cli lke kubeconfig-view <cluster-id>
3. Save the output to a file (e.g., kubeconfig.yaml).
4. Set the KUBECONFIG environment variable to point to this file.
export KUBECONFIG=path/to/kubeconfig.yaml
5. You should now be able to run kubectl commands against your LKE cluster.
Step 3: Deploy Your First Application
In the previous step, we deployed a simple Nginx application to your LKE cluster. However, there are several additional steps and configurations you can explore to make your application deployment more robust and production-ready.
1. Configure Persistent Storage
In the previous example, the Nginx pods were using ephemeral storage, which means that any data stored in the containers will be lost when the pods are terminated or restarted. For applications that require persistent data storage, you can use Kubernetes volumes and volume claims.
Here's an example of how you can create a persistent volume claim and use it in your Nginx deployment:
?# nginx-pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: nginx-pvc
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
# nginx-deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
replicas: 3
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:latest
ports:
- containerPort: 80
volumeMounts:
- name: nginx-storage
mountPath: /usr/share/nginx/html
volumes:
- name: nginx-storage
persistentVolumeClaim:
claimName: nginx-pvc
In this example, we create a persistent volume claim (PVC) of 1GiB storage, and mount it to the /usr/share/nginx/html directory in the Nginx container. This way, any content added to the Nginx document root will persist across pod restarts.
2. Configure Ingress
In the previous example, we exposed the Nginx service as a LoadBalancer type, which provisions a load balancer for external access. However, in production environments, you may want to use an Ingress controller to route traffic to your applications based on hostname or URL paths.
Here's an example of how you can configure an Ingress resource for your Nginx deployment:
# nginx-ingress.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: nginx-ingress
spec:
rules:
- http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: nginx-service
port:
number: 80
In this example, the Ingress resource routes all incoming HTTP traffic to the nginx-service Service. You would also need to set up an Ingress controller, such as the NGINX Ingress Controller or the Kubernetes Ingress NGINX, to handle the incoming traffic and load balancing.
3. Configure Horizontal Pod Autoscaling (HPA)
Horizontal Pod Autoscaling (HPA) allows you to automatically scale the number of pods in your deployment based on CPU or memory usage. This ensures that your application has enough resources to handle increased load, while also optimizing resource utilization.
Here's an example of how you can configure HPA for your Nginx deployment:
# nginx-hpa.yaml
apiVersion: autoscaling/v2beta1
kind: HorizontalPodAutoscaler
metadata:
name: nginx-hpa
spec:
scaleTargetRef:
apiVersion: apps/v1
kind: Deployment
name: nginx-deployment
minReplicas: 3
maxReplicas: 10
metrics:
- type: Resource
resource:
name: cpu
targetAverageUtilization: 50
In this example, the HPA will automatically scale the number of replicas for the nginx-deployment between 3 and 10 pods, based on the average CPU utilization across all pods. When the average CPU utilization exceeds 50%, HPA will spin up new pods to handle the increased load.
4. Configure Monitoring and Logging
Monitoring and logging are essential for maintaining the health and performance of your applications in a Kubernetes cluster. LKE supports various addons and integrations for monitoring and logging, such as Prometheus, Grafana, and Fluentd.
5. Explore Additional Kubernetes Resources
Kubernetes provides a wide range of resources and features to manage and configure your applications. Some additional resources you may want to explore include:
ConfigMaps and Secrets for managing application configurations and sensitive data
Jobs and CronJobs for running batch or scheduled tasks
StatefulSets for managing stateful applications
DaemonSets for running a copy of a pod on each node in the cluster
NetworkPolicies for controlling network traffic between pods
By exploring these additional features and configurations, you can build more robust and scalable applications on Linode Kubernetes Engine.
Conclusion
As you continue your journey with LKE, you'll find that the possibilities are huge. With its integration with Linode's cloud services, feature set, and comprehensive documentation, LKE provides a solid foundation for deploying and managing containerized workloads at scale.
Remember, the world of Kubernetes is evolving, and Linode Kubernetes Engine keeps pace with the latest advancements, ensuring that you have access to the latest features and capabilities. By staying up-to-date with the official documentation and exploring the vibrant Kubernetes community, you'll be well-equipped to tackle even the most complex application deployment and management challenges.