K8s

K8s - Kubernetes API Client for Elixir

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Features

  • A client API for humans
  • Kubernetes resources, groups, and CRDs are autodiscovered at boot time. No swagger file to include or override.
  • Client supports standard HTTP calls, async batches, wait on status, and watchers
  • Supports multiple clusters
  • Supports multiple authentication credentials

    • serviceaccount
    • token
    • certificate
    • auth-provider
  • Supports multiple kubernetes API
  • Tested against kubernetes swagger specs: 1.10+ and master
  • CRD support
  • Kubernetes resource and version helper functions
  • Kube config file parsing
  • Certificate and service account based auth
  • Pluggable auth providers
  • Macro free; fast compile & fast startup

Installation

The package can be installed by adding k8s to your list of dependencies in mix.exs:

def deps do
  [
    {:k8s, "~> 0.2"}
  ]
end

Usage

Check out the Usage Guide for in-depth examples.

Most functions are also written using doctests.

Testing K8s operations in your application

K8s ships with a K8s.Client.DynamicHTTPProvider for stubbing HTTP responses to kubernetes API requests.

This provider is used throughout the test suite for mocking HTTP responses.

defmodule MyApp.ResourceTest do
  use ExUnit.Case, async: true

  defmodule K8sMock do
    @base_url "https://localhost:6443"
    @namespaces_url @base_url <> "/api/v1/namespaces"

    def request(:get, @namespaces_url, _, _, _) do
      namespaces = [%{"metadata" => %{"name" => "default"}}]
      body = Jason.encode!(namespaces)
      {:ok, %HTTPoison.Response{status_code: 200, body: body}}
    end
  end

  setup do
    DynamicHTTPProvider.register(self(), __MODULE__.K8sMock)
  end

  test "gets namespaces" do
    operation = K8s.Client.get("v1", :namespaces)
    assert {:ok, namespaces} = K8s.Client.run(operation, :default)
    assert namespaces == [%{"metadata" => %{"name" => "default"}}]
  end
end

To see advanced examples of usage, check out these examples in the test suite:

Contributing

Adding support for a new version of kubernetes

Download the swagger spec for the new version. k8s doesn't use swagger to define the API, but it is used to drive property tests.

export NEW_VERSION_NUMBER=1.1n
make get/${NEW_VERSION_NUMBER}
make test/${NEW_VERSION_NUMBER}

Mock discovery responses exist to simulate runtime API discovery using the FileDriver

If new resources or APIs were added to kubernetes in the new version you will likely see one of these errors: unsupported_api_version and unsupported_resource.

Unsupported API Version errors

This error occurs when a new API is added to kubernetes.

Example: {:error, :unsupported_api_version, "scheduling.k8s.io/v1"}

Add the :unsupported_api_version to this mock configuration and rerun the test suite.

A config entry looks like:

// ...
 {
    "groupVersion": "scheduling.k8s.io/v1", // add the api version
    "kind": "APIResourceList", // leave as is
    "resources": [ // add a list of resources provided by the new `groupVersion`
      {
        "kind": "PriorityClass", // `kind` name
        "name": "priorityclasses", // plural name
        "namespaced": false, // namespaced or not
        "singularName": "",
        "verbs": [ // list of verbs supported by the new API
          "create",
          "delete",
          "deletecollection",
          "get",
          "list",
          "patch",
          "update",
          "watch"
        ]
      }
    ]
  },
// ...

Unsupported Resource errors

This error occurs when a new resource type is added to an existing API, similar to above you will need to add the resource to the list of resources.

The following config is missing runtimeclasses as a resource.

  {
    "groupVersion": "node.k8s.io/v1beta1",
    "kind": "APIResourceList",
    "resources": [
      {
        "kind": "Node",
        "name": "nodes",
        "namespaced": false,
        "singularName": "",
        "verbs": [
          "create",
          "delete",
          "deletecollection",
          "get",
          "list",
          "patch",
          "update",
          "watch"
        ]
      }
    ]
  },

After mocking:

  {
    "groupVersion": "node.k8s.io/v1beta1",
    "kind": "APIResourceList",
    "resources": [
      {
        "kind": "Node",
        "name": "nodes",
        "namespaced": false,
        "singularName": "",
        "verbs": [
          "create",
          "delete",
          "deletecollection",
          "get",
          "list",
          "patch",
          "update",
          "watch"
        ]
      },
      {
        "kind": "RuntimeClass",
        "name": "runtimeclasses",
        "namespaced": false,
        "singularName": "",
        "verbs": [
          "create",
          "delete",
          "deletecollection",
          "get",
          "list",
          "patch",
          "update",
          "watch"
        ]
      }
    ]
  },