Tutorial: Getting Started with @kubernetes-client/node
Introduction
@kubernetes-client/node is the official Node.js client library for Kubernetes. It provides a powerful and flexible way to interact with Kubernetes clusters programmatically. This tutorial will guide you through the basics of using @kubernetes-client/node in your Node.js applications.
Installation
To get started, install the @kubernetes-client/node package using npm:
npm install @kubernetes-client/node
Setting up the Client
First, let's import the necessary modules and create a Kubernetes client:
const k8s = require('@kubernetes-client/node');
async function main() {
const kc = new k8s.KubeConfig();
kc.loadFromDefault();
const client = kc.makeApiClient(k8s.CoreV1Api);
// Your code here
}
main().catch(console.error);
This code creates a KubeConfig object, loads the default configuration (usually from ~/.kube/config), and creates an API client for the Core V1 API.
Listing Pods
Let's start with a simple example of listing pods in the default namespace:
async function listPods() {
const kc = new k8s.KubeConfig();
kc.loadFromDefault();
const client = kc.makeApiClient(k8s.CoreV1Api);
try {
const res = await client.listNamespacedPod('default');
console.log('Pods in default namespace:');
for (const item of res.body.items) {
console.log(` - ${item.metadata.name}`);
}
} catch (err) {
console.error('Error listing pods:', err);
}
}
listPods();
This function will list all pods in the default namespace.
Creating a Deployment
Now, let's create a simple deployment:
const k8s = require('@kubernetes-client/node');
async function createDeployment() {
const kc = new k8s.KubeConfig();
kc.loadFromDefault();
const client = kc.makeApiClient(k8s.AppsV1Api);
const deployment = {
metadata: {
name: 'nginx-deployment'
},
spec: {
replicas: 3,
selector: {
matchLabels: {
app: 'nginx'
}
},
template: {
metadata: {
labels: {
app: 'nginx'
}
},
spec: {
containers: [{
name: 'nginx',
image: 'nginx:1.14.2',
ports: [{
containerPort: 80
}]
}]
}
}
}
};
try {
const res = await client.createNamespacedDeployment('default', deployment);
console.log('Deployment created');
} catch (err) {
console.error('Error creating deployment:', err);
}
}
createDeployment();
This function creates a deployment with three replicas of an Nginx container.
Watching Resources
@kubernetes-client/node also supports watching resources for changes:
const k8s = require('@kubernetes-client/node');
async function watchPods() {
const kc = new k8s.KubeConfig();
kc.loadFromDefault();
const watch = new k8s.Watch(kc);
try {
const req = await watch.watch('/api/v1/namespaces/default/pods',
{},
(type, apiObj) => {
console.log(`Pod ${apiObj.metadata.name} ${type}`);
},
(err) => {
console.log(err);
}
);
// Stop the watch after 30 seconds
setTimeout(() => {
req.abort();
}, 30000);
} catch (err) {
console.error('Error watching pods:', err);
}
}
watchPods();
This function sets up a watch on pods in the default namespace and logs any changes for 30 seconds.
Conclusion
This tutorial has covered the basics of using @kubernetes-client/node, including setting up the client, listing resources, creating deployments, and watching for changes. The library offers many more capabilities for interacting with your Kubernetes clusters. For more advanced usage and a complete API reference, check out the @kubernetes-client/node documentation.
Remember to handle errors appropriately and consider using TypeScript for better type checking and autocompletion when working with the Kubernetes API objects.
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