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Configuring envtest for integration tests

The controller-runtime/pkg/envtest Go library helps write integration tests for your controllers by setting up and starting an instance of etcd and the Kubernetes API server, without kubelet, controller-manager or other components.

Installation

The test make target, also called by the docker-build target, downloads a set of envtest binaries (described above) to run tests with. Typically nothing needs to be done on your part, as the download and install script is fully automated, although it does require bash to run.

If you would like to download the tarball containing these binaries, to use in a disconnected environment for example, run the following (Kubernetes version 1.19.2 is an example version):

K8S_VERSION=1.19.2
curl -sSLo envtest-bins.tar.gz "https://storage.googleapis.com/kubebuilder-tools/kubebuilder-tools-${K8S_VERSION}-$(go env GOOS)-$(go env GOARCH).tar.gz"

Then install them:

mkdir /opt/kubebuilder/testbin
tar -C /opt/kubebuilder/testbin --strip-components=1 -zvxf envtest-bins.tar.gz

Once these binaries are installed, you can either change the test target to:

test: manifests generate fmt vet
	go test ./... -coverprofile cover.out

Or configure the existing target to skip the download and point to a custom location:

make test SKIP_FETCH_TOOLS=1 KUBEBUILDER_ASSETS=/opt/kubebuilder/testbin

Writing tests

Using envtest in integration tests follows the general flow of:

import sigs.k8s.io/controller-runtime/pkg/envtest

//specify testEnv configuration
testEnv = &envtest.Environment{
	CRDDirectoryPaths: []string{filepath.Join("..", "config", "crd", "bases")},
}

//start testEnv
cfg, err = testEnv.Start()

//write test logic

//stop testEnv
err = testEnv.Stop()

kubebuilder does the boilerplate setup and teardown of testEnv for you, in the ginkgo test suite that it generates under the /controllers directory.

Logs from the test runs are prefixed with test-env.

Configuring your test control plane

Controller-runtime’s envtest framework requires kubectl, kube-apiserver, and etcd binaries be present locally to simulate the API portions of a real cluster.

For projects built with plugin v3+ (see your PROJECT file’s layout key), the make test command will install these binaries to the testbin/ directory and use them when running tests that use envtest.

You can use environment variables and/or flags to specify the kubectl,api-server and etcd setup within your integration tests.

Environment Variables

Variable nameTypeWhen to use
USE_EXISTING_CLUSTERbooleanInstead of setting up a local control plane, point to the control plane of an existing cluster.
KUBEBUILDER_ASSETSpath to directoryPoint integration tests to a directory containing all binaries (api-server, etcd and kubectl).
TEST_ASSET_KUBE_APISERVER, TEST_ASSET_ETCD, TEST_ASSET_KUBECTLpaths to, respectively, api-server, etcd and kubectl binariesSimilar to KUBEBUILDER_ASSETS, but more granular. Point integration tests to use binaries other than the default ones. These environment variables can also be used to ensure specific tests run with expected versions of these binaries.
KUBEBUILDER_CONTROLPLANE_START_TIMEOUT and KUBEBUILDER_CONTROLPLANE_STOP_TIMEOUTdurations in format supported by time.ParseDurationSpecify timeouts different from the default for the test control plane to (respectively) start and stop; any test run that exceeds them will fail.
KUBEBUILDER_ATTACH_CONTROL_PLANE_OUTPUTbooleanSet to true to attach the control plane’s stdout and stderr to os.Stdout and os.Stderr. This can be useful when debugging test failures, as output will include output from the control plane.

See that the test makefile target will ensure that all is properly setup when you are using it. However, if you would like to run the tests without use the Makefile targets, for example via an IDE, then you can set the environment variables directly in the code of your suite_test.go:

var _ = BeforeSuite(func(done Done) {
	Expect(os.Setenv("TEST_ASSET_KUBE_APISERVER", "../testbin/bin/kube-apiserver")).To(Succeed())
	Expect(os.Setenv("TEST_ASSET_ETCD", "../testbin/bin/etcd")).To(Succeed())
	Expect(os.Setenv("TEST_ASSET_KUBECTL", "../testbin/bin/kubectl")).To(Succeed())

	logf.SetLogger(zap.New(zap.WriteTo(GinkgoWriter), zap.UseDevMode(true)))
	testenv = &envtest.Environment{}

	_, err := testenv.Start()
	Expect(err).NotTo(HaveOccurred())

	close(done)
}, 60)

var _ = AfterSuite(func() {
	Expect(testenv.Stop()).To(Succeed())

	Expect(os.Unsetenv("TEST_ASSET_KUBE_APISERVER")).To(Succeed())
	Expect(os.Unsetenv("TEST_ASSET_ETCD")).To(Succeed())
	Expect(os.Unsetenv("TEST_ASSET_KUBECTL")).To(Succeed())

})

Flags

Here’s an example of modifying the flags with which to start the API server in your integration tests, compared to the default values in envtest.DefaultKubeAPIServerFlags:

customApiServerFlags := []string{
	"--secure-port=6884",
	"--admission-control=MutatingAdmissionWebhook",
}

apiServerFlags := append([]string(nil), envtest.DefaultKubeAPIServerFlags...)
apiServerFlags = append(apiServerFlags, customApiServerFlags...)

testEnv = &envtest.Environment{
	CRDDirectoryPaths: []string{filepath.Join("..", "config", "crd", "bases")},
	KubeAPIServerFlags: apiServerFlags,
}

Testing considerations

Unless you’re using an existing cluster, keep in mind that no built-in controllers are running in the test context. In some ways, the test control plane will behave differently from “real” clusters, and that might have an impact on how you write tests. One common example is garbage collection; because there are no controllers monitoring built-in resources, objects do not get deleted, even if an OwnerReference is set up.

To test that the deletion lifecycle works, test the ownership instead of asserting on existence. For example:

expectedOwnerReference := v1.OwnerReference{
	Kind:       "MyCoolCustomResource",
	APIVersion: "my.api.example.com/v1beta1",
	UID:        "d9607e19-f88f-11e6-a518-42010a800195",
	Name:       "userSpecifiedResourceName",
}
Expect(deployment.ObjectMeta.OwnerReferences).To(ContainElement(expectedOwnerReference))