e2e/storage: testing of external storage drivers

It is useful to apply the storage testsuite also to "external" (=
out-of-tree) storage drivers. One way of doing that is setting up a
custom E2E test suite, but that's still quite a bit of work.

An easier alternative is to parameterize the Kubernetes e2e.test
binary at runtime so that it instantiates the testsuite for one or
more drivers. Some parameters have to be provided before starting the
test because they define configuration and capabilities of the driver
and its storage backend that cannot be discovered at runtime. This is
done by populating the DriverDefinition with the content of the file
that the new -storage.testdriver parameters points to.

The universal .yaml and .json decoder from Kubernetes is used. It's
flexible, but has some downsides:
- currently ignores unknown fields (see kubernetes#71589)
- poor error messages when fields have the wrong type

Storage drivers have to be installed in the test cluster before
starting e2e.test. Only tests involving dynamically provisioned
volumes are currently supported.

test/e2e/BUILD

@@ -33,6 +33,7 @@ go_test(
         "//test/e2e/scheduling:go_default_library",
         "//test/e2e/servicecatalog:go_default_library",
         "//test/e2e/storage:go_default_library",
+        "//test/e2e/storage/external:go_default_library",
         "//test/e2e/ui:go_default_library",
         "//test/e2e/windows:go_default_library",
         "//test/utils/image:go_default_library",

test/e2e/e2e_test.go

@@ -51,6 +51,7 @@ import (
 	_ "k8s.io/kubernetes/test/e2e/scheduling"
 	_ "k8s.io/kubernetes/test/e2e/servicecatalog"
 	_ "k8s.io/kubernetes/test/e2e/storage"
+	_ "k8s.io/kubernetes/test/e2e/storage/external"
 	_ "k8s.io/kubernetes/test/e2e/ui"
 	_ "k8s.io/kubernetes/test/e2e/windows"
 )

test/e2e/storage/BUILD

@@ -95,6 +95,7 @@ filegroup(
     srcs = [
         ":package-srcs",
         "//test/e2e/storage/drivers:all-srcs",
+        "//test/e2e/storage/external:all-srcs",
         "//test/e2e/storage/testpatterns:all-srcs",
         "//test/e2e/storage/testsuites:all-srcs",
         "//test/e2e/storage/utils:all-srcs",

test/e2e/storage/external/BUILD

@@ -0,0 +1,48 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["external.go"],
+    importpath = "k8s.io/kubernetes/test/e2e/storage/external",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/api/legacyscheme:go_default_library",
+        "//staging/src/k8s.io/api/storage/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/unstructured:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//test/e2e/framework:go_default_library",
+        "//test/e2e/storage/testpatterns:go_default_library",
+        "//test/e2e/storage/testsuites:go_default_library",
+        "//vendor/github.com/onsi/ginkgo:go_default_library",
+        "//vendor/github.com/onsi/gomega:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["external_test.go"],
+    data = glob(["testdata/**"]),
+    embed = [":go_default_library"],
+    deps = [
+        "//staging/src/k8s.io/apimachinery/pkg/util/sets:go_default_library",
+        "//test/e2e/storage/testsuites:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

test/e2e/storage/external/README.md

@@ -0,0 +1,49 @@
+When a test suite like test/e2e/e2e.test from Kubernetes includes this
+package, the -storage.testdriver parameter can be used one or more
+times to enabling testing of a certain pre-installed storage driver.
+
+The parameter takes as argument the name of a .yaml or .json file. The
+filename can be absolute or relative to --repo-root. The content of
+the file is used to populate a struct that defines how to test the
+driver. For a full definition of the struct see the external.go file.
+
+Here is an example for the CSI hostpath driver:
+
+    ShortName: mytest
+    StorageClass:
+      FromName: true
+    SnapshotClass:
+      FromName: true
+    DriverInfo:
+      Name: csi-hostpath
+      Capabilities:
+        persistence: true
+        dataSource: true
+        multipods: true
+
+Currently there is no checking for unknown fields, i.e. only file
+entries that match with struct entries are used and other entries are
+silently ignored, so beware of typos.
+
+For each driver, the storage tests from `test/e2e/storage/testsuites`
+are added for that driver with `External Storage [Driver: <Name>]` as
+prefix.
+
+To run just those tests for the example above, put that content into
+`/tmp/hostpath-testdriver.yaml` and invoke:
+
+    ginkgo -p -focus='External.Storage.*csi-hostpath' \
+           -skip='\[Feature:|\[Disruptive\]' \
+           ./test/e2e \
+           -- \
+           -storage.testdriver=/tmp/hostpath-testdriver.yaml
+
+This disables tests which depend on optional features. Those tests
+must be run by selecting them explicitly in an environment that
+supports them, for example snapshotting:
+
+    ginkgo -p -focus='External.Storage.*csi-hostpath.*\[Feature:VolumeSnapshotDataSource\]' \
+           -skip='\[Disruptive\]' \
+           ./test/e2e \
+           -- \
+           -storage.testdriver=/tmp/hostpath-testdriver.yaml

test/e2e/storage/external/external.go

@@ -0,0 +1,276 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package external
+
+import (
+	"flag"
+	"io/ioutil"
+
+	"github.com/pkg/errors"
+
+	storagev1 "k8s.io/api/storage/v1"
+	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/sets"
+	"k8s.io/kubernetes/pkg/api/legacyscheme"
+	"k8s.io/kubernetes/test/e2e/framework"
+	"k8s.io/kubernetes/test/e2e/storage/testpatterns"
+	"k8s.io/kubernetes/test/e2e/storage/testsuites"
+
+	"github.com/onsi/ginkgo"
+	"github.com/onsi/gomega"
+)
+
+// List of testSuites to be executed for each external driver.
+var csiTestSuites = []func() testsuites.TestSuite{
+	testsuites.InitProvisioningTestSuite,
+	testsuites.InitSnapshottableTestSuite,
+	testsuites.InitSubPathTestSuite,
+	testsuites.InitVolumeIOTestSuite,
+	testsuites.InitVolumeModeTestSuite,
+	testsuites.InitVolumesTestSuite,
+}
+
+func init() {
+	flag.Var(testDriverParameter{}, "storage.testdriver", "name of a .yaml or .json file that defines a driver for storage testing, can be used more than once")
+}
+
+// testDriverParameter is used to hook loading of the driver
+// definition file and test instantiation into argument parsing: for
+// each of potentially many parameters, Set is called and then does
+// both immediately. There is no other code location between argument
+// parsing and starting of the test suite where those test could be
+// defined.
+type testDriverParameter struct {
+}
+
+var _ flag.Value = testDriverParameter{}
+
+func (t testDriverParameter) String() string {
+	return "<.yaml or .json file>"
+}
+
+func (t testDriverParameter) Set(filename string) error {
+	driver, err := t.loadDriverDefinition(filename)
+	if err != nil {
+		return err
+	}
+	if driver.DriverInfo.Name == "" {
+		return errors.Errorf("%q: DriverInfo.Name not set", filename)
+	}
+
+	description := "External Storage " + testsuites.GetDriverNameWithFeatureTags(driver)
+	ginkgo.Describe(description, func() {
+		testsuites.DefineTestSuite(driver, csiTestSuites)
+	})
+
+	return nil
+}
+
+func (t testDriverParameter) loadDriverDefinition(filename string) (*driverDefinition, error) {
+	if filename == "" {
+		return nil, errors.New("missing file name")
+	}
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		return nil, err
+	}
+	// Some reasonable defaults follow.
+	driver := &driverDefinition{
+		DriverInfo: testsuites.DriverInfo{
+			SupportedFsType: sets.NewString(
+				"", // Default fsType
+			),
+		},
+		ClaimSize: "5Gi",
+	}
+	// TODO: strict checking of the file content once https://github.com/kubernetes/kubernetes/pull/71589
+	// or something similar is merged.
+	if err := runtime.DecodeInto(legacyscheme.Codecs.UniversalDecoder(), data, driver); err != nil {
+		return nil, errors.Wrap(err, filename)
+	}
+	return driver, nil
+}
+
+var _ testsuites.TestDriver = &driverDefinition{}
+
+// We have to implement the interface because dynamic PV may or may
+// not be supported. driverDefinition.SkipUnsupportedTest checks that
+// based on the actual driver definition.
+var _ testsuites.DynamicPVTestDriver = &driverDefinition{}
+
+// Same for snapshotting.
+var _ testsuites.SnapshottableTestDriver = &driverDefinition{}
+
+// runtime.DecodeInto needs a runtime.Object but doesn't do any
+// deserialization of it and therefore none of the methods below need
+// an implementation.
+var _ runtime.Object = &driverDefinition{}
+
+// DriverDefinition needs to be filled in via a .yaml or .json
+// file. It's methods then implement the TestDriver interface, using
+// nothing but the information in this struct.
+type driverDefinition struct {
+	// DriverInfo is the static information that the storage testsuite
+	// expects from a test driver. See test/e2e/storage/testsuites/testdriver.go
+	// for details. The only field with a non-zero default is the list of
+	// supported file systems (SupportedFsType): it is set so that tests using
+	// the default file system are enabled.
+	DriverInfo testsuites.DriverInfo
+
+	// ShortName is used to create unique names for test cases and test resources.
+	ShortName string
+
+	// StorageClass must be set to enable dynamic provisioning tests.
+	// The default is to not run those tests.
+	StorageClass struct {
+		// FromName set to true enables the usage of a storage
+		// class with DriverInfo.Name as provisioner and no
+		// parameters.
+		FromName bool
+
+		// FromFile is used only when FromName is false.  It
+		// loads a storage class from the given .yaml or .json
+		// file. File names are resolved by the
+		// framework.testfiles package, which typically means
+		// that they can be absolute or relative to the test
+		// suite's --repo-root parameter.
+		//
+		// This can be used when the storage class is meant to have
+		// additional parameters.
+		FromFile string
+	}
+
+	// SnapshotClass must be set to enable snapshotting tests.
+	// The default is to not run those tests.
+	SnapshotClass struct {
+		// FromName set to true enables the usage of a
+		// snapshotter class with DriverInfo.Name as provisioner.
+		FromName bool
+
+		// TODO (?): load from file
+	}
+
+	// ClaimSize defines the desired size of dynamically
+	// provisioned volumes. Default is "5GiB".
+	ClaimSize string
+
+	// ClientNodeName selects a specific node for scheduling test pods.
+	// Can be left empty. Most drivers should not need this and instead
+	// use topology to ensure that pods land on the right node(s).
+	ClientNodeName string
+}
+
+func (d *driverDefinition) DeepCopyObject() runtime.Object {
+	return nil
+}
+
+func (d *driverDefinition) GetObjectKind() schema.ObjectKind {
+	return nil
+}
+
+func (d *driverDefinition) GetDriverInfo() *testsuites.DriverInfo {
+	return &d.DriverInfo
+}
+
+func (d *driverDefinition) SkipUnsupportedTest(pattern testpatterns.TestPattern) {
+	supported := false
+	// TODO (?): add support for more volume types
+	switch pattern.VolType {
+	case testpatterns.DynamicPV:
+		if d.StorageClass.FromName || d.StorageClass.FromFile != "" {
+			supported = true
+		}
+	}
+	if !supported {
+		framework.Skipf("Driver %q does not support volume type %q - skipping", d.DriverInfo.Name, pattern.VolType)
+	}
+
+	supported = false
+	switch pattern.SnapshotType {
+	case "":
+		supported = true
+	case testpatterns.DynamicCreatedSnapshot:
+		if d.SnapshotClass.FromName {
+			supported = true
+		}
+	}
+	if !supported {
+		framework.Skipf("Driver %q does not support snapshot type %q - skipping", d.DriverInfo.Name, pattern.SnapshotType)
+	}
+}
+
+func (d *driverDefinition) GetDynamicProvisionStorageClass(config *testsuites.PerTestConfig, fsType string) *storagev1.StorageClass {
+	f := config.Framework
+
+	if d.StorageClass.FromName {
+		provisioner := d.DriverInfo.Name
+		parameters := map[string]string{}
+		ns := f.Namespace.Name
+		suffix := provisioner + "-sc"
+		if fsType != "" {
+			parameters["csi.storage.k8s.io/fstype"] = fsType
+		}
+
+		return testsuites.GetStorageClass(provisioner, parameters, nil, ns, suffix)
+	}
+
+	items, err := f.LoadFromManifests(d.StorageClass.FromFile)
+	gomega.Expect(err).NotTo(gomega.HaveOccurred(), "load storage class from %s", d.StorageClass.FromFile)
+	gomega.Expect(len(items)).To(gomega.Equal(1), "exactly one item from %s", d.StorageClass.FromFile)
+
+	err = f.PatchItems(items...)
+	gomega.Expect(err).NotTo(gomega.HaveOccurred(), "patch items")
+
+	sc, ok := items[0].(*storagev1.StorageClass)
+	gomega.Expect(ok).To(gomega.BeTrue(), "storage class from %s", d.StorageClass.FromFile)
+	if fsType != "" {
+		if sc.Parameters == nil {
+			sc.Parameters = map[string]string{}
+		}
+		sc.Parameters["csi.storage.k8s.io/fstype"] = fsType
+	}
+	return sc
+}
+
+func (d *driverDefinition) GetSnapshotClass(config *testsuites.PerTestConfig) *unstructured.Unstructured {
+	if !d.SnapshotClass.FromName {
+		framework.Skipf("Driver %q does not support snapshotting - skipping", d.DriverInfo.Name)
+	}
+
+	snapshotter := config.GetUniqueDriverName()
+	parameters := map[string]string{}
+	ns := config.Framework.Namespace.Name
+	suffix := snapshotter + "-vsc"
+
+	return testsuites.GetSnapshotClass(snapshotter, parameters, ns, suffix)
+}
+
+func (d *driverDefinition) GetClaimSize() string {
+	return d.ClaimSize
+}
+
+func (d *driverDefinition) PrepareTest(f *framework.Framework) (*testsuites.PerTestConfig, func()) {
+	config := &testsuites.PerTestConfig{
+		Driver:         d,
+		Prefix:         "external",
+		Framework:      f,
+		ClientNodeName: d.ClientNodeName,
+	}
+	return config, func() {}
+}