/x/kubernetes_client

This module implements several ways of sending authenticated requests to the Kubernetes API from deno scripts.

Kubernetes is a complex architechure which likes using sophisticated networking concepts, while Deno is a relatively young runtime, so there’s some mismatch in capabilities. Therefor one client implementation cannot work in every case, and different Deno flags enable supporting different setups.

This library is intended as a building block. If you are unsure how to issue a specific request from your own library/code, or if your usage results in any TODO: ... error message from my code, please feel free to file a Github Issue.

Usage

Here’s a basic request, listing all Pods in the default namespace. It uses the autoDetectClient() entrypoint which returns the first usable client.

Note: This example shows a manual HTTP request. To use the Kubernetes APIs more easily, consider also using /x/kubernetes_apis

import { autoDetectClient } from 'https://deno.land/x/kubernetes_client/mod.ts';
const kubernetes = await autoDetectClient();

const podList = await kubernetes.performRequest({
  method: 'GET',
  path: `/api/v1/namespaces/default/pods`,
  expectJson: true, // run JSON.parse on the response body
});
console.log(podList);

// see demo.ts for more request examples (streaming responses, etc)

To get started on local development, autoDetectClient will most likely decide to call out to your kubectl installation to make each network call. This only requires the --allow-run=kubectl Deno flag.

To use other clients, more flags are necesary. See “Client Implementations” below for more information on flags and other HTTP clients.

The kubectl client logs the issued commands if --verbose is passed to the Deno program.

Check out lib/contract.ts to see the type/API contract.

Changelog

• v0.3.2 on 2021-11-28: Fix another regression on modern Deno, related to client certificates. Or more exactly the lack thereof when running in-cluster.

• v0.3.1 on 2021-11-27: Fix cluster certificate authority setup in KubeConfigRestClient on Deno v1.15.0 and later.

• v0.3.0 on 2021-08-29: Allow TLS authentication, when supported by Deno (#7). More consistently use --verbose flag (#4). Updated deps to /std@0.105.0. Now requires Deno v1.11 or later.

• v0.2.4 on 2021-05-09: Clean up Deno-specific code in stream-transformers.ts. This also improves compatibility with Deno Deploy. Updated deps to /std@0.95.0.

• v0.2.3 on 2021-04-26: Full fix for certificate data encodings. Addresses a partial fix in v0.2.3 which introduced an InCluster regression.

• v0.2.2 on 2021-04-21: Fix for using certificate data stored within kubeconfig. The Base64 encoding was not being respected previously.

• v0.2.1 on 2021-03-26: Better Windows support from @jhannes. Checks for the $USERPROFILE variable as well as $HOME.

• v0.2.0 on 2021-02-27: Rewrote KubeConfig handling and removed stable/unstable split. There’s only two transport implementations now: KubectlRaw and KubeConfig.

• v0.1.3 on 2020-12-29: Improved KubectlRaw Patch support. Now supports namespaced resources ;) and knows that subresources can’t be patched.

• v0.1.2 on 2020-12-27: Initial KubectlRaw Patch support. Also exports the Reflector implementation and plumbs the unstable Kubeconfig client more.

• v0.1.1 on 2020-12-24: Add a generic Reflector implementation. This is useful for consuming a pairing of list & watch APIs.

• v0.1.0 on 2020-11-16: Initial publication, with KubectlRaw and InCluster clients. Also includes ReadableStream transformers, useful for consuming watch streams.

Client Implementations

An error message is shown when no client is usable, something like this:

Error: Failed to load any possible Kubernetes clients:
  - InCluster PermissionDenied: Requires read access to "/var/run/secrets/kubernetes.io/serviceaccount/namespace", run again with the --allow-read flag
  - KubeConfig PermissionDenied: Requires env access to "KUBECONFIG", run again with the --allow-env flag
  - KubectlProxy PermissionDenied: Requires net access to "localhost:8001", run again with the --allow-net flag
  - KubectlRaw PermissionDenied: Requires run access to "kubectl", run again with the --allow-run flag

Each client has different pros and cons:

• KubectlRawRestClient invokes kubectl --raw for every HTTP call. Excellent for development, though a couple APIs are not possible to implement.

  Flags: --allow-run=kubectl

• KubeConfigRestClient uses Deno’s fetch() to issue HTTP requests. There’s a few different functions to configure it:

  • forInCluster() uses a pod’s ServiceAccount to automatically authenticate. This is what is used when you deploy your script to a cluster.

    Flags: --allow-read=/var/run/secrets/kubernetes.io --allow-net=kubernetes.default.svc.cluster.local plus either --unstable or --cert=/var/run/secrets/kubernetes.io/serviceaccount/ca.crt

    Lazy flags: --allow-read --allow-net --unstable

  • forKubectlProxy() expects a kubectl proxy command to be running and talks directly to it without auth.

    This allows a full range-of-motion for development purposes regardless of the Kubernetes configuration.

    Flags: --allow-net=localhost:8001 given that kubectl proxy is already running at that URL.

  • readKubeConfig(path?, context?) (or forKubeConfig(config, context?)) tries using the given config (or $HOME/.kube/config if none is given) as faithfully as possible.

    This requires a lot of flags depending on the config file, and in some cases simply cannot work. For example https://<ip-address> server values are not currently supported by Deno, and invoking auth plugins such as gcloud aren’t implemented yet, so any short-lived tokens in the kubeconfig must already be fresh. Trial & error works here :)

    Entry-level flags: --allow-env --allow-net --allow-read=$HOME/.kube

Related: API Typings

This module is only implementing the HTTP/transport part of talking to Kubernetes. You’ll likely also want Typescript interfaces around actually working with Kubernetes resources.

API typings are available in a sibling project: kubernetes_apis published to /x/kubernetes_apis.

Of course, for some situations it might make sense to issue specific requests directly in which case using this client library alone might make more sense.

TODO

• Support for kubectl proxy
• Add filtering to Reflector implementation (e.g. by annotation)