@ccremer/kubernetes-client-fetch v0.2.0

Kubernetes Client

Query Kubernetes API from the browser. Ideal for SPA-like apps and CRDs.

Features

• Common CRUD operations on resources:

  • get
  • list
  • watch
  • create
  • update
  • patch
  • delete

• Support for most query parameters

• Generic types

  • Some built-in, basic types available, growing as needed.
  • Add your own types

• Interface-first, includes default implementation using the Fetch API.

• Authentication with Kubernetes token (JWT). Extensible.

Getting started

Install the client

npm install @ccremer/kubernetes-client @ccremer/kubernetes-client-fetch

Setup the client and make a request

import { KubeClientBuilder } from '@ccremer/kubernetes-client-fetch'
import { SelfSubjectRulesReview } from '@ccremer/kubernetes-client/types/authorization.k8s.io'

// token:
// a valid JWT for Kubernetes.
// This could come from a password-field, oauth service etc.
const token = '...'
// apiUrl:
// Either a CORS-enabled remote URL with https,
// or proxied by the webserver to the actual API.
const apiUrl = '/api'

const client = KubeClientBuilder.DefaultClient(token, apiUrl)
client
  .create<SelfSubjectRulesReview>({
    apiVersion: 'authorization.k8s.io/v1',
    kind: 'SelfSubjectRulesReview',
    spec: {
      namespace: 'default',
    },
  })
  .then((selfSubjectRulesReview) => {
    console.debug('Created client with permissions', selfSubjectRulesReview.status)
  })
  .catch((err) => {
    console.error('could not fetch object', err)
  })

You can also provide your own resource type, as long as it fulfills the KubeMeta interface contract.

import { KubeObject } from '@ccremer/kubernetes-client/types/core'

export interface MyCustomResource extends KubeObject {
  apiVersion: 'customgroup/v1'
  kind: 'CustomResource'
  spec: {
    field: string
  }
}

ℹ️ The client doesn't set a default name or namespace when querying, so be sure you set the correct metadata.

Accessing Kubernetes API

Because of CORS, the default implementation expects the Kubernetes API to be available at /api and /apis, proxied by whatever webserver you are running. You can change the endpoint for it, e.g. set to /kube/ (no trailing slash), so that the endpoints are concatenated to /kube/api and /kube/apis.

Example configuration for Vite in Dev mode:

import { defineConfig } from 'vite'
import 'dotenv/config'

// https://vitejs.dev/config/
export default defineConfig(() => {
  return {
    server: {
      proxy: {
        '/apis': {
          target: process.env.VITE_KUBERNETES_API_URL,
          changeOrigin: true,
          secure: false,
        },
        '/api': {
          target: process.env.VITE_KUBERNETES_API_URL,
          changeOrigin: true,
          secure: false,
        },
      },
    },
  }
})

The /api endpoint is for core resources like Namespaces or Pods, while /apis is for resources under a group like apps for Deployments.

Alternatively, you can set the endpoint to a full URL like https://console.cluster.6443. However, keep CORS and other browser limitations in mind if your app is served under a different domain.

Extension points

The default built-in client can be extended in various points.

• The KubeClientBuilder accepts various interfaces that are injected into the Client class.
• Each API endpoint for a resource is generated based on metadata like apiVersion and kind. Implement UrlGenerator interface to provide your own generator and supply it to the builder.
• Each HTTP request requires authorization. Implement the Authorizer interface and supply your implementation to the builder.
• You can provide your own custom fetch()-like function to the builder.

Known Issues

• The Config class returns a KubeConfig-like structure complete with cluster and user information. However, currently only a variant with a JWT token is supported, created with Config.FromToken() combined with DefaultAuthorizer.
• There is no validation to the passed in payloads or returned results.
• Many Kubernetes resource types are missing, and they're not (yet?) generated from the Kubernetes API scheme. Implement your own or better yet, contribute to @ccremer/kubernetes-client :)

Production readiness

This library is fairly new. Expect breaking changes as new experience is gained.

Other than that, this package follows SemVer.

Why

There is an official Kubernetes client. However, it's not yet ready for browsers and development seems a bit slow.