gKube

A Gomega Kubernetes API matcher/assertion library to help make writing tests simpler with less boilerplate logic. It wraps the controller-runtime dynamic client and includes some pod sub-resource helpers using client-go.

A simple example of creating a namespace and asserting on some fields with JSONPath:

package simple

import (
	"testing"

	. "github.com/matt-simons/gkube"
	. "github.com/onsi/ginkgo/v2"
	. "github.com/onsi/gomega"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

var _ = Describe("Simple use of the KubernetesHelper", Ordered, func() {

	var k8s KubernetesHelper
	var namespace *corev1.Namespace

	BeforeAll(func() {
		k8s = NewKubernetesHelper()
		namespace = &corev1.Namespace{
			ObjectMeta: metav1.ObjectMeta{
				Name: "simple",
			},
		}
	})

	It("should create a namespace", func() {
		Eventually(k8s.Create(namespace)).Should(Succeed())
		Eventually(k8s.Object(namespace)).Should(
			WithJSONPath("{.status.phase}", Equal(corev1.NamespacePhase("Active"))),
		)
	})

	It("should filter a list of namespaces using a JSONPath", func() {
		Eventually(k8s.Objects(&corev1.NamespaceList{})).Should(
			WithJSONPath("{.items[*].metadata.name}", ContainElement("simple")),
		)
	})

	AfterAll(func() {
		Eventually(k8s.Delete(namespace, GracePeriodSeconds(30))).Should(Succeed())
	})
})

func TestKubernetesHelper(t *testing.T) {
	RegisterFailHandler(Fail)
	RunSpecs(t, "Simple")
}

More examples can be found at https://github.com/matt-simons/gkube-examples

Helper

A Kubernetes Helper interface designed to be used with Gomega assertions.

Options

The helper can be constructed by providing zero or many options:

• WithClient passes a client for interacting with Kubernetes API servers.
• WithConfig passes config for initializing REST configs for talking to the Kubernetes API.
• WithScheme passes a scheme which contains information associating Go types with Kubernetes groups, versions, and kinds.
• WithContext passes a context which carries deadlines, cancellation signals, and other request-scoped values.

Example for using the KubernetesHelper with Openshift Custom Resources:

import openshiftapi "github.com/openshift/api"

...

scheme := runtime.NewScheme()
openshiftapi.Install(scheme)
k8s := NewKubernetesHelper(WithScheme(scheme))

Client Helpers

Create, Delete, DeleteAllOf, Get, List, Patch, Update wrap their respective client functions by returning a function which can be called by Gomega's Eventually or Consistently. The function returns an error if it occurs.

Object Helpers

Object and Objects use Get to retrieve a specified Object or ObjectList, however they are wrapped in a func() client.Object which is passed to a matcher.

When using Object the object's name must be provided and namespace if it is namespaced.

Client Options

The controller-runtime's client options are also surfaced for convenience when gkube is dot imported. Zero or many options can be provided to all compatible helpers, e.g.:

Eventually(k8s.Objects(&corev1.ConfigMapList{}, InNamespace("default"))).Should(WithJSONPath(
	"{.items[*].metadata.name}", ContainElement("my-configmap")))

Eventually(k8s.DeleteAllOf(&corev1.Pod{},
	InNamespace("default"), MatchingLabels{"app": "foo"})).Should(Succeed())

Pod Subresource Helpers

These helpers interact with some of the more useful pod subresources.

Exec

Executes a command in a running pod, this helper functions similarly to gexec. It allows you to assert against the exit code, and stream output into gbytes.Buffer to allow you make assertions against output.

Eventually(k8s.Object(pod)).WithTimeout(time.Minute).Should(WithJSONPath(
	`{.status.phase}`, BeEquivalentTo(corev1.PodRunning)))

execOpts := &corev1.PodExecOptions{
	Container: pod.Spec.Containers[0].Name,
	Command:   []string{"/bin/sh", "-c", "echo hellopod"},
	Stdout:    true,
	Stderr:    true,
}
session, err := k8s.Exec(pod, execOpts, time.Minute, GinkgoWriter, GinkgoWriter)
Expect(err).ShouldNot(HaveOccurred())

Eventually(session).WithTimeout(time.Minute).Should(Exit())
Eventually(session).Should(Say("hellopod"))

Log

TBD

PortForward

TBD

Matchers

WithJSONPath

WithJSONPath is a transformer function. It transforms the expected object by an expression then evaluates a matcher against the result(s), it can be used in conjunction with the Object or Objects helpers.

If only one result is produced from the expression then the results list is flattened for convenience. It's is generally recommended to keep expressions simple and specific to a field. If you need to validate multiple fields, use multiple assertions or the EqualObject matcher.

See Kubernetes JSONPath documentation for more details and examples: https://kubernetes.io/docs/reference/kubectl/jsonpath/

Example asserting a pod phase:

Eventually(k8s.Object(pod)).WithTimeout(time.Minute).Should(WithJSONPath(
	"{.status.phase}", BeEquivalentTo(corev1.PodRunning),
)

Example asserting a specific condition from a deployment:

Eventually(k8s.Object(deployment)).WithTimeout(time.Minute).Should(WithJSONPath(
	`{.status.conditions[?(@.type=="Available")]}`,
	MatchFields(IgnoreExtras, Fields{
		"Status": BeEquivalentTo(corev1.ConditionTrue),
		"Reason": Equal("MinimumReplicasAvailable"),
	}),
))

EqualObject

From the CAPI project: https://github.com/kubernetes-sigs/cluster-api/blob/main/internal/matchers/matchers.go.

Can be used in conjunction with the Object or Objects helpers. It matches the whole Object.

The matcher can accept one of two options, IgnorePaths or AllowPaths:

• IgnorePaths instructs the Matcher to ignore given paths when computing a diff.
• AllowPaths instructs the Matcher to restrict its diff to the given paths. If empty the Matcher will look at all paths.

IgnoreAutogeneratedMetadata is a predefined IgnorePaths that contains the paths for all the metadata fields that are commonly set by the client and APIServer.

cm := &corev1.ConfigMap{ObjectMeta: metav1.ObjectMeta{Name: "config", Namespace: "default"}}
expected := &corev1.ConfigMap{
	ObjectMeta: metav1.ObjectMeta{Name: "config", Namespace: "default"},
	Data: map[string]string{"key", "val"},
}
Eventually(k8s.Object(cm)).Should(EqualObject(expected, IgnoreAutogeneratedMetadata))