Replace godep with dep

vendor/k8s.io/apiserver/plugin/pkg/audit/BUILD

@@ -0,0 +1,28 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["doc.go"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//staging/src/k8s.io/apiserver/plugin/pkg/audit/log:all-srcs",
+        "//staging/src/k8s.io/apiserver/plugin/pkg/audit/webhook:all-srcs",
+    ],
+    tags = ["automanaged"],
+)

vendor/k8s.io/apiserver/plugin/pkg/audit/doc.go

@@ -0,0 +1,18 @@
+/*
+Copyright 2017 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 audit contains implementations for pkg/audit/AuditBackend interface
+package audit // import "k8s.io/apiserver/plugin/pkg/audit"

vendor/k8s.io/apiserver/plugin/pkg/audit/log/BUILD

@@ -0,0 +1,50 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["backend.go"],
+    deps = [
+        "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/audit:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["backend_test.go"],
+    library = ":go_default_library",
+    deps = [
+        "//vendor/github.com/pborman/uuid:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apimachinery/announced:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apimachinery/registered:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/types:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/install:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/v1beta1:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/audit:go_default_library",
+    ],
+)

vendor/k8s.io/apiserver/plugin/pkg/audit/log/backend.go

@@ -0,0 +1,93 @@
+/*
+Copyright 2017 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 log
+
+import (
+	"fmt"
+	"io"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	auditinternal "k8s.io/apiserver/pkg/apis/audit"
+	"k8s.io/apiserver/pkg/audit"
+)
+
+const (
+	// FormatLegacy saves event in 1-line text format.
+	FormatLegacy = "legacy"
+	// FormatJson saves event in structured json format.
+	FormatJson = "json"
+)
+
+// AllowedFormats are the formats known by log backend.
+var AllowedFormats = []string{
+	FormatLegacy,
+	FormatJson,
+}
+
+type backend struct {
+	out          io.Writer
+	format       string
+	groupVersion schema.GroupVersion
+}
+
+var _ audit.Backend = &backend{}
+
+func NewBackend(out io.Writer, format string, groupVersion schema.GroupVersion) audit.Backend {
+	return &backend{
+		out:          out,
+		format:       format,
+		groupVersion: groupVersion,
+	}
+}
+
+func (b *backend) ProcessEvents(events ...*auditinternal.Event) {
+	for _, ev := range events {
+		b.logEvent(ev)
+	}
+}
+
+func (b *backend) logEvent(ev *auditinternal.Event) {
+	line := ""
+	switch b.format {
+	case FormatLegacy:
+		line = audit.EventString(ev) + "\n"
+	case FormatJson:
+		bs, err := runtime.Encode(audit.Codecs.LegacyCodec(b.groupVersion), ev)
+		if err != nil {
+			audit.HandlePluginError("log", err, ev)
+			return
+		}
+		line = string(bs[:])
+	default:
+		audit.HandlePluginError("log", fmt.Errorf("log format %q is not in list of known formats (%s)",
+			b.format, strings.Join(AllowedFormats, ",")), ev)
+		return
+	}
+	if _, err := fmt.Fprint(b.out, line); err != nil {
+		audit.HandlePluginError("log", err, ev)
+	}
+}
+
+func (b *backend) Run(stopCh <-chan struct{}) error {
+	return nil
+}
+
+func (b *backend) Shutdown() {
+	// Nothing to do here.
+}

vendor/k8s.io/apiserver/plugin/pkg/audit/log/backend_test.go

@@ -0,0 +1,175 @@
+/*
+Copyright 2017 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 log
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"regexp"
+	"testing"
+	"time"
+
+	"github.com/pborman/uuid"
+
+	"k8s.io/apimachinery/pkg/apimachinery/announced"
+	"k8s.io/apimachinery/pkg/apimachinery/registered"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/types"
+	auditinternal "k8s.io/apiserver/pkg/apis/audit"
+	"k8s.io/apiserver/pkg/apis/audit/install"
+	auditv1beta1 "k8s.io/apiserver/pkg/apis/audit/v1beta1"
+	"k8s.io/apiserver/pkg/audit"
+)
+
+// NOTE: Copied from webhook backend to register auditv1beta1 to scheme
+var (
+	groupFactoryRegistry = make(announced.APIGroupFactoryRegistry)
+	registry             = registered.NewOrDie("")
+)
+
+func init() {
+	allGVs := []schema.GroupVersion{auditv1beta1.SchemeGroupVersion}
+	registry.RegisterVersions(allGVs)
+	if err := registry.EnableVersions(allGVs...); err != nil {
+		panic(fmt.Sprintf("failed to enable version %v", allGVs))
+	}
+	install.Install(groupFactoryRegistry, registry, audit.Scheme)
+}
+
+func TestLogEventsLegacy(t *testing.T) {
+	for _, test := range []struct {
+		event    *auditinternal.Event
+		expected string
+	}{
+		{
+			&auditinternal.Event{
+				AuditID: types.UID(uuid.NewRandom().String()),
+			},
+			`[\d\:\-\.\+TZ]+ AUDIT: id="[\w-]+" stage="" ip="<unknown>" method="" user="<none>" groups="<none>" as="<self>" asgroups="<lookup>" namespace="<none>" uri="" response="<deferred>"`,
+		},
+		{
+			&auditinternal.Event{
+				ResponseStatus: &metav1.Status{
+					Code: 200,
+				},
+				RequestURI: "/apis/rbac.authorization.k8s.io/v1/roles",
+				SourceIPs: []string{
+					"127.0.0.1",
+				},
+				Timestamp: metav1.NewTime(time.Now()),
+				AuditID:   types.UID(uuid.NewRandom().String()),
+				Stage:     auditinternal.StageRequestReceived,
+				Verb:      "get",
+				User: auditinternal.UserInfo{
+					Username: "admin",
+					Groups: []string{
+						"system:masters",
+						"system:authenticated",
+					},
+				},
+				ObjectRef: &auditinternal.ObjectReference{
+					Namespace: "default",
+				},
+			},
+			`[\d\:\-\.\+TZ]+ AUDIT: id="[\w-]+" stage="RequestReceived" ip="127.0.0.1" method="get" user="admin" groups="\\"system:masters\\",\\"system:authenticated\\"" as="<self>" asgroups="<lookup>" namespace="default" uri="/apis/rbac.authorization.k8s.io/v1/roles" response="200"`,
+		},
+		{
+			&auditinternal.Event{
+				AuditID: types.UID(uuid.NewRandom().String()),
+				Level:   auditinternal.LevelMetadata,
+				ObjectRef: &auditinternal.ObjectReference{
+					Resource:    "foo",
+					APIVersion:  "v1",
+					Subresource: "bar",
+				},
+			},
+			`[\d\:\-\.\+TZ]+ AUDIT: id="[\w-]+" stage="" ip="<unknown>" method="" user="<none>" groups="<none>" as="<self>" asgroups="<lookup>" namespace="<none>" uri="" response="<deferred>"`,
+		},
+	} {
+		var buf bytes.Buffer
+		backend := NewBackend(&buf, FormatLegacy, auditv1beta1.SchemeGroupVersion)
+		backend.ProcessEvents(test.event)
+		match, err := regexp.MatchString(test.expected, buf.String())
+		if err != nil {
+			t.Errorf("Unexpected error matching line %v", err)
+			continue
+		}
+		if !match {
+			t.Errorf("Unexpected line of audit: %s", buf.String())
+		}
+	}
+}
+
+func TestLogEventsJson(t *testing.T) {
+	for _, event := range []*auditinternal.Event{
+		{
+			AuditID: types.UID(uuid.NewRandom().String()),
+		},
+		{
+			ResponseStatus: &metav1.Status{
+				Code: 200,
+			},
+			RequestURI: "/apis/rbac.authorization.k8s.io/v1/roles",
+			SourceIPs: []string{
+				"127.0.0.1",
+			},
+			// When encoding to json format, the nanosecond part of timestamp is
+			// lost and it will become zero when we decode event back, so we rounding
+			// timestamp down to a multiple of second.
+			Timestamp: metav1.NewTime(time.Now().Truncate(time.Second)),
+			AuditID:   types.UID(uuid.NewRandom().String()),
+			Stage:     auditinternal.StageRequestReceived,
+			Verb:      "get",
+			User: auditinternal.UserInfo{
+				Username: "admin",
+				Groups: []string{
+					"system:masters",
+					"system:authenticated",
+				},
+			},
+			ObjectRef: &auditinternal.ObjectReference{
+				Namespace: "default",
+			},
+		},
+		{
+			AuditID: types.UID(uuid.NewRandom().String()),
+			Level:   auditinternal.LevelMetadata,
+			ObjectRef: &auditinternal.ObjectReference{
+				Resource:    "foo",
+				APIVersion:  "v1",
+				Subresource: "bar",
+			},
+		},
+	} {
+		var buf bytes.Buffer
+		backend := NewBackend(&buf, FormatJson, auditv1beta1.SchemeGroupVersion)
+		backend.ProcessEvents(event)
+		// decode events back and compare with the original one.
+		result := &auditinternal.Event{}
+		decoder := audit.Codecs.UniversalDecoder(auditv1beta1.SchemeGroupVersion)
+		if err := runtime.DecodeInto(decoder, buf.Bytes(), result); err != nil {
+			t.Errorf("failed decoding buf: %s", buf.String())
+			continue
+		}
+		if !reflect.DeepEqual(event, result) {
+			t.Errorf("The result event should be the same with the original one, \noriginal: \n%#v\n result: \n%#v", event, result)
+		}
+	}
+}

vendor/k8s.io/apiserver/plugin/pkg/audit/webhook/BUILD

@@ -0,0 +1,58 @@
+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = [
+        "webhook_test.go",
+        "webhook_v1alpha1_test.go",
+    ],
+    library = ":go_default_library",
+    deps = [
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+        "//vendor/github.com/stretchr/testify/require:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/serializer/json:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/v1alpha1:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/v1beta1:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/audit:go_default_library",
+        "//vendor/k8s.io/client-go/tools/clientcmd/api/v1:go_default_library",
+    ],
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["webhook.go"],
+    deps = [
+        "//vendor/k8s.io/apimachinery/pkg/apimachinery/announced:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apimachinery/registered:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/runtime/schema:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/util/runtime:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/install:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/v1alpha1:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/apis/audit/v1beta1:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/audit:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/util/webhook:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

vendor/k8s.io/apiserver/plugin/pkg/audit/webhook/webhook.go

@@ -0,0 +1,361 @@
+/*
+Copyright 2017 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 webhook implements the audit.Backend interface using HTTP webhooks.
+package webhook
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"k8s.io/apimachinery/pkg/apimachinery/announced"
+	"k8s.io/apimachinery/pkg/apimachinery/registered"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/runtime"
+	auditinternal "k8s.io/apiserver/pkg/apis/audit"
+	"k8s.io/apiserver/pkg/apis/audit/install"
+	auditv1alpha1 "k8s.io/apiserver/pkg/apis/audit/v1alpha1"
+	auditv1beta1 "k8s.io/apiserver/pkg/apis/audit/v1beta1"
+	"k8s.io/apiserver/pkg/audit"
+	"k8s.io/apiserver/pkg/util/webhook"
+)
+
+const (
+	// ModeBatch indicates that the webhook should buffer audit events
+	// internally, sending batch updates either once a certain number of
+	// events have been received or a certain amount of time has passed.
+	ModeBatch = "batch"
+	// ModeBlocking causes the webhook to block on every attempt to process
+	// a set of events. This causes requests to the API server to wait for a
+	// round trip to the external audit service before sending a response.
+	ModeBlocking = "blocking"
+)
+
+// AllowedModes is the modes known by this webhook.
+var AllowedModes = []string{
+	ModeBatch,
+	ModeBlocking,
+}
+
+const (
+	// Default configuration values for ModeBatch.
+	//
+	// TODO(ericchiang): Make these value configurable. Maybe through a
+	// kubeconfig extension?
+	defaultBatchBufferSize = 1000        // Buffer up to 1000 events before blocking.
+	defaultBatchMaxSize    = 100         // Only send 100 events at a time.
+	defaultBatchMaxWait    = time.Minute // Send events at least once a minute.
+)
+
+// The plugin name reported in error metrics.
+const pluginName = "webhook"
+
+// NewBackend returns an audit backend that sends events over HTTP to an external service.
+// The mode indicates the caching behavior of the webhook. Either blocking (ModeBlocking)
+// or buffered with batch POSTs (ModeBatch).
+func NewBackend(kubeConfigFile string, mode string, groupVersion schema.GroupVersion) (audit.Backend, error) {
+	switch mode {
+	case ModeBatch:
+		return newBatchWebhook(kubeConfigFile, groupVersion)
+	case ModeBlocking:
+		return newBlockingWebhook(kubeConfigFile, groupVersion)
+	default:
+		return nil, fmt.Errorf("webhook mode %q is not in list of known modes (%s)",
+			mode, strings.Join(AllowedModes, ","))
+	}
+}
+
+var (
+	// NOTE: Copied from other webhook implementations
+	//
+	// Can we make these passable to NewGenericWebhook?
+	groupFactoryRegistry = make(announced.APIGroupFactoryRegistry)
+	// TODO(audit): figure out a general way to let the client choose their preferred version
+	registry = registered.NewOrDie("")
+)
+
+func init() {
+	allGVs := []schema.GroupVersion{auditv1alpha1.SchemeGroupVersion, auditv1beta1.SchemeGroupVersion}
+	registry.RegisterVersions(allGVs)
+	if err := registry.EnableVersions(allGVs...); err != nil {
+		panic(fmt.Sprintf("failed to enable version %v", allGVs))
+	}
+	install.Install(groupFactoryRegistry, registry, audit.Scheme)
+}
+
+func loadWebhook(configFile string, groupVersion schema.GroupVersion) (*webhook.GenericWebhook, error) {
+	return webhook.NewGenericWebhook(registry, audit.Codecs, configFile, []schema.GroupVersion{groupVersion}, 0)
+}
+
+func newBlockingWebhook(configFile string, groupVersion schema.GroupVersion) (*blockingBackend, error) {
+	w, err := loadWebhook(configFile, groupVersion)
+	if err != nil {
+		return nil, err
+	}
+	return &blockingBackend{w}, nil
+}
+
+type blockingBackend struct {
+	w *webhook.GenericWebhook
+}
+
+func (b *blockingBackend) Run(stopCh <-chan struct{}) error {
+	return nil
+}
+
+func (b *blockingBackend) Shutdown() {
+	// nothing to do here
+}
+
+func (b *blockingBackend) ProcessEvents(ev ...*auditinternal.Event) {
+	if err := b.processEvents(ev...); err != nil {
+		audit.HandlePluginError(pluginName, err, ev...)
+	}
+}
+
+func (b *blockingBackend) processEvents(ev ...*auditinternal.Event) error {
+	var list auditinternal.EventList
+	for _, e := range ev {
+		list.Items = append(list.Items, *e)
+	}
+	// NOTE: No exponential backoff because this is the blocking webhook
+	// mode. Any attempts to retry will block API server requests.
+	return b.w.RestClient.Post().Body(&list).Do().Error()
+}
+
+func newBatchWebhook(configFile string, groupVersion schema.GroupVersion) (*batchBackend, error) {
+	w, err := loadWebhook(configFile, groupVersion)
+	if err != nil {
+		return nil, err
+	}
+
+	return &batchBackend{
+		w:            w,
+		buffer:       make(chan *auditinternal.Event, defaultBatchBufferSize),
+		maxBatchSize: defaultBatchMaxSize,
+		maxBatchWait: defaultBatchMaxWait,
+		shutdownCh:   make(chan struct{}),
+	}, nil
+}
+
+type batchBackend struct {
+	w *webhook.GenericWebhook
+
+	// Channel to buffer events in memory before sending them on the webhook.
+	buffer chan *auditinternal.Event
+	// Maximum number of events that can be sent at once.
+	maxBatchSize int
+	// Amount of time to wait after sending events before force sending another set.
+	//
+	// Receiving maxBatchSize events will always trigger a send, regardless of
+	// if this amount of time has been reached.
+	maxBatchWait time.Duration
+
+	// Channel to signal that the sending routine has stopped and therefore
+	// it's safe to assume that no new requests will be initiated.
+	shutdownCh chan struct{}
+
+	// The sending routine locks reqMutex for reading before initiating a new
+	// goroutine to send a request. This goroutine then unlocks reqMutex for
+	// reading when completed. The Shutdown method locks reqMutex for writing
+	// after the sending routine has exited. When reqMutex is locked for writing,
+	// all requests have been completed and no new will be spawned, since the
+	// sending routine is not running anymore.
+	reqMutex sync.RWMutex
+}
+
+func (b *batchBackend) Run(stopCh <-chan struct{}) error {
+	go func() {
+		// Signal that the sending routine has exited.
+		defer close(b.shutdownCh)
+
+		b.runSendingRoutine(stopCh)
+
+		// Handle the events that were received after the last buffer
+		// scraping and before this line. Since the buffer is closed, no new
+		// events will come through.
+		for {
+			if last := func() bool {
+				// Recover from any panic in order to try to send all remaining events.
+				// Note, that in case of a panic, the return value will be false and
+				// the loop execution will continue.
+				defer runtime.HandleCrash()
+
+				events := b.collectLastEvents()
+				b.sendBatchEvents(events)
+				return len(events) == 0
+			}(); last {
+				break
+			}
+		}
+	}()
+	return nil
+}
+
+func (b *batchBackend) Shutdown() {
+	<-b.shutdownCh
+
+	// Write locking reqMutex will guarantee that all requests will be completed
+	// by the time the goroutine continues the execution. Since this line is
+	// executed after shutdownCh was closed, no new requests will follow this
+	// lock, because read lock is called in the same goroutine that closes
+	// shutdownCh before exiting.
+	b.reqMutex.Lock()
+	b.reqMutex.Unlock()
+}
+
+// runSendingRoutine runs a loop that collects events from the buffer. When
+// stopCh is closed, runSendingRoutine stops and closes the buffer.
+func (b *batchBackend) runSendingRoutine(stopCh <-chan struct{}) {
+	defer close(b.buffer)
+
+	for {
+		func() {
+			// Recover from any panics caused by this function so a panic in the
+			// goroutine can't bring down the main routine.
+			defer runtime.HandleCrash()
+
+			t := time.NewTimer(b.maxBatchWait)
+			defer t.Stop() // Release ticker resources
+
+			b.sendBatchEvents(b.collectEvents(stopCh, t.C))
+		}()
+
+		select {
+		case <-stopCh:
+			return
+		default:
+		}
+	}
+}
+
+// collectEvents attempts to collect some number of events in a batch.
+//
+// The following things can cause collectEvents to stop and return the list
+// of events:
+//
+//   * Some maximum number of events are received.
+//   * Timer has passed, all queued events are sent.
+//   * StopCh is closed, all queued events are sent.
+//
+func (b *batchBackend) collectEvents(stopCh <-chan struct{}, timer <-chan time.Time) []auditinternal.Event {
+	var events []auditinternal.Event
+
+L:
+	for i := 0; i < b.maxBatchSize; i++ {
+		select {
+		case ev, ok := <-b.buffer:
+			// Buffer channel was closed and no new events will follow.
+			if !ok {
+				break L
+			}
+			events = append(events, *ev)
+		case <-timer:
+			// Timer has expired. Send whatever events are in the queue.
+			break L
+		case <-stopCh:
+			// Webhook has shut down. Send the last events.
+			break L
+		}
+	}
+
+	return events
+}
+
+// collectLastEvents assumes that the buffer was closed. It collects the first
+// maxBatchSize events from the closed buffer into a batch and returns them.
+func (b *batchBackend) collectLastEvents() []auditinternal.Event {
+	var events []auditinternal.Event
+
+	for i := 0; i < b.maxBatchSize; i++ {
+		ev, ok := <-b.buffer
+		if !ok {
+			break
+		}
+		events = append(events, *ev)
+	}
+
+	return events
+}
+
+// sendBatchEvents sends a POST requests with the event list in a goroutine
+// and logs any error encountered.
+func (b *batchBackend) sendBatchEvents(events []auditinternal.Event) {
+	if len(events) == 0 {
+		return
+	}
+
+	list := auditinternal.EventList{Items: events}
+
+	// Locking reqMutex for read will guarantee that the shutdown process will
+	// block until the goroutine started below is finished. At the same time, it
+	// will not prevent other batches from being proceed further this point.
+	b.reqMutex.RLock()
+	go func() {
+		// Execute the webhook POST in a goroutine to keep it from blocking.
+		// This lets the webhook continue to drain the queue immediatly.
+
+		defer b.reqMutex.RUnlock()
+		defer runtime.HandleCrash()
+
+		err := webhook.WithExponentialBackoff(0, func() error {
+			return b.w.RestClient.Post().Body(&list).Do().Error()
+		})
+		if err != nil {
+			impacted := make([]*auditinternal.Event, len(events))
+			for i := range events {
+				impacted[i] = &events[i]
+			}
+			audit.HandlePluginError(pluginName, err, impacted...)
+		}
+	}()
+	return
+}
+
+func (b *batchBackend) ProcessEvents(ev ...*auditinternal.Event) {
+	for i, e := range ev {
+		// Per the audit.Backend interface these events are reused after being
+		// sent to the Sink. Deep copy and send the copy to the queue.
+		event := e.DeepCopy()
+
+		// The following mechanism is in place to support the situation when audit
+		// events are still coming after the backend was shut down.
+		var sendErr error
+		func() {
+			// If the backend was shut down and the buffer channel was closed, an
+			// attempt to add an event to it will result in panic that we should
+			// recover from.
+			defer func() {
+				if err := recover(); err != nil {
+					sendErr = errors.New("audit webhook shut down")
+				}
+			}()
+
+			select {
+			case b.buffer <- event:
+			default:
+				sendErr = errors.New("audit webhook queue blocked")
+			}
+		}()
+		if sendErr != nil {
+			audit.HandlePluginError(pluginName, sendErr, ev[i:]...)
+			return
+		}
+	}
+}

vendor/k8s.io/apiserver/plugin/pkg/audit/webhook/webhook_test.go

@@ -0,0 +1,405 @@
+/*
+Copyright 2017 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 webhook
+
+import (
+	stdjson "encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"reflect"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	auditinternal "k8s.io/apiserver/pkg/apis/audit"
+	auditv1beta1 "k8s.io/apiserver/pkg/apis/audit/v1beta1"
+	"k8s.io/apiserver/pkg/audit"
+	"k8s.io/client-go/tools/clientcmd/api/v1"
+)
+
+// newWebhookHandler returns a handler which recieves webhook events and decodes the
+// request body. The caller passes a callback which is called on each webhook POST.
+// The object passed to cb is of the same type as list.
+func newWebhookHandler(t *testing.T, list runtime.Object, cb func(events runtime.Object)) http.Handler {
+	s := json.NewSerializer(json.DefaultMetaFactory, audit.Scheme, audit.Scheme, false)
+	return &testWebhookHandler{
+		t:          t,
+		list:       list,
+		onEvents:   cb,
+		serializer: s,
+	}
+}
+
+type testWebhookHandler struct {
+	t *testing.T
+
+	list     runtime.Object
+	onEvents func(events runtime.Object)
+
+	serializer runtime.Serializer
+}
+
+func (t *testWebhookHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	err := func() error {
+		body, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			return fmt.Errorf("read webhook request body: %v", err)
+		}
+
+		obj, _, err := t.serializer.Decode(body, nil, t.list.DeepCopyObject())
+		if err != nil {
+			return fmt.Errorf("decode request body: %v", err)
+		}
+		if reflect.TypeOf(obj).Elem() != reflect.TypeOf(t.list).Elem() {
+			return fmt.Errorf("expected %T, got %T", t.list, obj)
+		}
+		t.onEvents(obj)
+		return nil
+	}()
+
+	if err == nil {
+		io.WriteString(w, "{}")
+		return
+	}
+	// In a goroutine, can't call Fatal.
+	assert.NoError(t.t, err, "failed to read request body")
+	http.Error(w, err.Error(), http.StatusInternalServerError)
+}
+
+func newTestBlockingWebhook(t *testing.T, endpoint string, groupVersion schema.GroupVersion) *blockingBackend {
+	return newWebhook(t, endpoint, ModeBlocking, groupVersion).(*blockingBackend)
+}
+
+func newTestBatchWebhook(t *testing.T, endpoint string, groupVersion schema.GroupVersion) *batchBackend {
+	return newWebhook(t, endpoint, ModeBatch, groupVersion).(*batchBackend)
+}
+
+func newWebhook(t *testing.T, endpoint string, mode string, groupVersion schema.GroupVersion) audit.Backend {
+	config := v1.Config{
+		Clusters: []v1.NamedCluster{
+			{Cluster: v1.Cluster{Server: endpoint, InsecureSkipTLSVerify: true}},
+		},
+	}
+	f, err := ioutil.TempFile("", "k8s_audit_webhook_test_")
+	require.NoError(t, err, "creating temp file")
+
+	defer func() {
+		f.Close()
+		os.Remove(f.Name())
+	}()
+
+	// NOTE(ericchiang): Do we need to use a proper serializer?
+	require.NoError(t, stdjson.NewEncoder(f).Encode(config), "writing kubeconfig")
+
+	backend, err := NewBackend(f.Name(), mode, groupVersion)
+	require.NoError(t, err, "initializing backend")
+
+	return backend
+}
+
+func TestWebhook(t *testing.T) {
+	gotEvents := false
+	defer func() { require.True(t, gotEvents, "no events received") }()
+
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		gotEvents = true
+	}))
+	defer s.Close()
+
+	backend := newTestBlockingWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+
+	// Ensure this doesn't return a serialization error.
+	event := &auditinternal.Event{}
+	require.NoError(t, backend.processEvents(event), "failed to send events")
+}
+
+// waitForEmptyBuffer indicates when the sendBatchEvents method has read from the
+// existing buffer. This lets test coordinate closing a timer and stop channel
+// until the for loop has read from the buffer.
+func waitForEmptyBuffer(b *batchBackend) {
+	for len(b.buffer) != 0 {
+		time.Sleep(time.Millisecond)
+	}
+}
+
+func TestBatchWebhookMaxEvents(t *testing.T) {
+	nRest := 10
+	events := make([]*auditinternal.Event, defaultBatchMaxSize+nRest) // greater than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1beta1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+
+	backend.ProcessEvents(events...)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time, 1)
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, defaultBatchMaxSize, <-got, "did not get batch max size")
+
+	go func() {
+		waitForEmptyBuffer(backend) // wait for the buffer to empty
+		timer <- time.Now()         // Trigger the wait timeout
+	}()
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, nRest, <-got, "failed to get the rest of the events")
+}
+
+func TestBatchWebhookStopCh(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	expected := len(events)
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1beta1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+	backend.ProcessEvents(events...)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time)
+
+	go func() {
+		waitForEmptyBuffer(backend)
+		close(stopCh) // stop channel has stopped
+	}()
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, expected, <-got, "get queued events after timer expires")
+}
+
+func TestBatchWebhookProcessEventsAfterStop(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan struct{})
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		close(got)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+	stopCh := make(chan struct{})
+
+	backend.Run(stopCh)
+	close(stopCh)
+	<-backend.shutdownCh
+	backend.ProcessEvents(events...)
+	assert.Equal(t, 0, len(backend.buffer), "processed events after the backed has been stopped")
+}
+
+func TestBatchWebhookShutdown(t *testing.T) {
+	events := make([]*auditinternal.Event, 1)
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan struct{})
+	contReqCh := make(chan struct{})
+	shutdownCh := make(chan struct{})
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		close(got)
+		<-contReqCh
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+	backend.ProcessEvents(events...)
+
+	go func() {
+		// Assume stopCh was closed.
+		close(backend.buffer)
+		backend.sendBatchEvents(backend.collectLastEvents())
+	}()
+
+	<-got
+
+	go func() {
+		close(backend.shutdownCh)
+		backend.Shutdown()
+		close(shutdownCh)
+	}()
+
+	// Wait for some time in case there's a bug that allows for the Shutdown
+	// method to exit before all requests has been completed.
+	time.Sleep(1 * time.Second)
+	select {
+	case <-shutdownCh:
+		t.Fatal("Backend shut down before all requests finished")
+	default:
+		// Continue.
+	}
+
+	close(contReqCh)
+	<-shutdownCh
+}
+
+func TestBatchWebhookEmptyBuffer(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	expected := len(events)
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1beta1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time, 1)
+
+	timer <- time.Now() // Timer is done.
+
+	// Buffer is empty, no events have been queued. This should exit but send no events.
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+
+	// Send additional events after the sendBatchEvents has been called.
+	backend.ProcessEvents(events...)
+	go func() {
+		waitForEmptyBuffer(backend)
+		timer <- time.Now()
+	}()
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+
+	// Make sure we didn't get a POST with zero events.
+	require.Equal(t, expected, <-got, "expected one event")
+}
+
+func TestBatchBufferFull(t *testing.T) {
+	events := make([]*auditinternal.Event, defaultBatchBufferSize+1) // More than buffered size
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		// Do nothing.
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+
+	// Make sure this doesn't block.
+	backend.ProcessEvents(events...)
+}
+
+func TestBatchRun(t *testing.T) {
+
+	// Divisable by max batch size so we don't have to wait for a minute for
+	// the test to finish.
+	events := make([]*auditinternal.Event, defaultBatchMaxSize*3)
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := new(int64)
+	want := len(events)
+
+	wg := new(sync.WaitGroup)
+	wg.Add(want)
+	done := make(chan struct{})
+
+	go func() {
+		wg.Wait()
+		// When the expected number of events have been received, close the channel.
+		close(done)
+	}()
+
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(obj runtime.Object) {
+		events := obj.(*auditv1beta1.EventList)
+		atomic.AddInt64(got, int64(len(events.Items)))
+		wg.Add(-len(events.Items))
+	}))
+	defer s.Close()
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+
+	// Test the Run codepath. E.g. that the spawned goroutines behave correctly.
+	backend.Run(stopCh)
+
+	backend.ProcessEvents(events...)
+
+	select {
+	case <-done:
+		// Received all the events.
+	case <-time.After(2 * time.Minute):
+		t.Errorf("expected %d events got %d", want, atomic.LoadInt64(got))
+	}
+}
+
+func TestBatchConcurrentRequests(t *testing.T) {
+	events := make([]*auditinternal.Event, defaultBatchBufferSize) // Don't drop events
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	wg := new(sync.WaitGroup)
+	wg.Add(len(events))
+
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1beta1.EventList{}, func(events runtime.Object) {
+		wg.Add(-len(events.(*auditv1beta1.EventList).Items))
+
+		// Since the webhook makes concurrent requests, blocking on the webhook response
+		// shouldn't block the webhook from sending more events.
+		//
+		// Wait for all responses to be received before sending the response.
+		wg.Wait()
+	}))
+	defer s.Close()
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1beta1.SchemeGroupVersion)
+	backend.Run(stopCh)
+
+	backend.ProcessEvents(events...)
+	// Wait for the webhook to receive all events.
+	wg.Wait()
+}

vendor/k8s.io/apiserver/plugin/pkg/audit/webhook/webhook_v1alpha1_test.go

@@ -0,0 +1,289 @@
+/*
+Copyright 2017 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 webhook
+
+import (
+	"net/http/httptest"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	auditinternal "k8s.io/apiserver/pkg/apis/audit"
+	auditv1alpha1 "k8s.io/apiserver/pkg/apis/audit/v1alpha1"
+)
+
+func TestBatchWebhookMaxEventsV1Alpha1(t *testing.T) {
+	nRest := 10
+	events := make([]*auditinternal.Event, defaultBatchMaxSize+nRest) // greater than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1alpha1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+
+	backend.ProcessEvents(events...)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time, 1)
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, defaultBatchMaxSize, <-got, "did not get batch max size")
+
+	go func() {
+		waitForEmptyBuffer(backend) // wait for the buffer to empty
+		timer <- time.Now()         // Trigger the wait timeout
+	}()
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, nRest, <-got, "failed to get the rest of the events")
+}
+
+func TestBatchWebhookStopChV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	expected := len(events)
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1alpha1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+	backend.ProcessEvents(events...)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time)
+
+	go func() {
+		waitForEmptyBuffer(backend)
+		close(stopCh) // stop channel has stopped
+	}()
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+	require.Equal(t, expected, <-got, "get queued events after timer expires")
+}
+
+func TestBatchWebhookProcessEventsAfterStopV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan struct{})
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		close(got)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+	stopCh := make(chan struct{})
+
+	backend.Run(stopCh)
+	close(stopCh)
+	<-backend.shutdownCh
+	backend.ProcessEvents(events...)
+	assert.Equal(t, 0, len(backend.buffer), "processed events after the backed has been stopped")
+}
+
+func TestBatchWebhookShutdownV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, 1)
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := make(chan struct{})
+	contReqCh := make(chan struct{})
+	shutdownCh := make(chan struct{})
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		close(got)
+		<-contReqCh
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+	backend.ProcessEvents(events...)
+
+	go func() {
+		// Assume stopCh was closed.
+		close(backend.buffer)
+		backend.sendBatchEvents(backend.collectLastEvents())
+	}()
+
+	<-got
+
+	go func() {
+		close(backend.shutdownCh)
+		backend.Shutdown()
+		close(shutdownCh)
+	}()
+
+	// Wait for some time in case there's a bug that allows for the Shutdown
+	// method to exit before all requests has been completed.
+	time.Sleep(1 * time.Second)
+	select {
+	case <-shutdownCh:
+		t.Fatal("Backend shut down before all requests finished")
+	default:
+		// Continue.
+	}
+
+	close(contReqCh)
+	<-shutdownCh
+}
+
+func TestBatchWebhookEmptyBufferV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, 1) // less than max size.
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	expected := len(events)
+	got := make(chan int, 2)
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		got <- len(events.(*auditv1alpha1.EventList).Items)
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+
+	stopCh := make(chan struct{})
+	timer := make(chan time.Time, 1)
+
+	timer <- time.Now() // Timer is done.
+
+	// Buffer is empty, no events have been queued. This should exit but send no events.
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+
+	// Send additional events after the sendBatchEvents has been called.
+	backend.ProcessEvents(events...)
+	go func() {
+		waitForEmptyBuffer(backend)
+		timer <- time.Now()
+	}()
+
+	backend.sendBatchEvents(backend.collectEvents(stopCh, timer))
+
+	// Make sure we didn't get a POST with zero events.
+	require.Equal(t, expected, <-got, "expected one event")
+}
+
+func TestBatchBufferFullV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, defaultBatchBufferSize+1) // More than buffered size
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		// Do nothing.
+	}))
+	defer s.Close()
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+
+	// Make sure this doesn't block.
+	backend.ProcessEvents(events...)
+}
+
+func TestBatchRunV1Alpha1(t *testing.T) {
+
+	// Divisable by max batch size so we don't have to wait for a minute for
+	// the test to finish.
+	events := make([]*auditinternal.Event, defaultBatchMaxSize*3)
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	got := new(int64)
+	want := len(events)
+
+	wg := new(sync.WaitGroup)
+	wg.Add(want)
+	done := make(chan struct{})
+
+	go func() {
+		wg.Wait()
+		// When the expected number of events have been received, close the channel.
+		close(done)
+	}()
+
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(obj runtime.Object) {
+		events := obj.(*auditv1alpha1.EventList)
+		atomic.AddInt64(got, int64(len(events.Items)))
+		wg.Add(-len(events.Items))
+	}))
+	defer s.Close()
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+
+	// Test the Run codepath. E.g. that the spawned goroutines behave correctly.
+	backend.Run(stopCh)
+
+	backend.ProcessEvents(events...)
+
+	select {
+	case <-done:
+		// Received all the events.
+	case <-time.After(2 * time.Minute):
+		t.Errorf("expected %d events got %d", want, atomic.LoadInt64(got))
+	}
+}
+
+func TestBatchConcurrentRequestsV1Alpha1(t *testing.T) {
+	events := make([]*auditinternal.Event, defaultBatchBufferSize) // Don't drop events
+	for i := range events {
+		events[i] = &auditinternal.Event{}
+	}
+
+	wg := new(sync.WaitGroup)
+	wg.Add(len(events))
+
+	s := httptest.NewServer(newWebhookHandler(t, &auditv1alpha1.EventList{}, func(events runtime.Object) {
+		wg.Add(-len(events.(*auditv1alpha1.EventList).Items))
+
+		// Since the webhook makes concurrent requests, blocking on the webhook response
+		// shouldn't block the webhook from sending more events.
+		//
+		// Wait for all responses to be received before sending the response.
+		wg.Wait()
+	}))
+	defer s.Close()
+
+	stopCh := make(chan struct{})
+	defer close(stopCh)
+
+	backend := newTestBatchWebhook(t, s.URL, auditv1alpha1.SchemeGroupVersion)
+	backend.Run(stopCh)
+
+	backend.ProcessEvents(events...)
+	// Wait for the webhook to receive all events.
+	wg.Wait()
+}