mirror of https://github.com/k3s-io/k3s
134 lines
4.2 KiB
Go
134 lines
4.2 KiB
Go
/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package webhook implements the audit.Backend interface using HTTP webhooks.
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package webhook
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import (
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"context"
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"fmt"
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"time"
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"k8s.io/apimachinery/pkg/runtime/schema"
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auditinternal "k8s.io/apiserver/pkg/apis/audit"
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"k8s.io/apiserver/pkg/apis/audit/install"
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"k8s.io/apiserver/pkg/audit"
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"k8s.io/apiserver/pkg/util/webhook"
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"k8s.io/client-go/rest"
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utiltrace "k8s.io/utils/trace"
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)
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const (
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// PluginName is the name of this plugin, to be used in help and logs.
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PluginName = "webhook"
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// DefaultInitialBackoff is the default amount of time to wait before
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// retrying sending audit events through a webhook.
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DefaultInitialBackoff = 10 * time.Second
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)
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func init() {
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install.Install(audit.Scheme)
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}
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// retryOnError enforces the webhook client to retry requests
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// on error regardless of its nature.
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// The default implementation considers a very limited set of
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// 'retriable' errors, assuming correct use of HTTP codes by
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// external webhooks.
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// That may easily lead to dropped audit events. In fact, there is
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// hardly any error that could be a justified reason NOT to retry
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// sending audit events if there is even a slight chance that the
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// receiving service gets back to normal at some point.
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func retryOnError(err error) bool {
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if err != nil {
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return true
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}
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return false
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}
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func loadWebhook(configFile string, groupVersion schema.GroupVersion, initialBackoff time.Duration) (*webhook.GenericWebhook, error) {
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w, err := webhook.NewGenericWebhook(audit.Scheme, audit.Codecs, configFile,
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[]schema.GroupVersion{groupVersion}, initialBackoff)
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w.ShouldRetry = retryOnError
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return w, err
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}
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type backend struct {
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w *webhook.GenericWebhook
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name string
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}
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// NewDynamicBackend returns an audit backend configured from a REST client that
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// sends events over HTTP to an external service.
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func NewDynamicBackend(rc *rest.RESTClient, initialBackoff time.Duration) audit.Backend {
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return &backend{
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w: &webhook.GenericWebhook{
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RestClient: rc,
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InitialBackoff: initialBackoff,
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ShouldRetry: retryOnError,
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},
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name: fmt.Sprintf("dynamic_%s", PluginName),
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}
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}
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// NewBackend returns an audit backend that sends events over HTTP to an external service.
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func NewBackend(kubeConfigFile string, groupVersion schema.GroupVersion, initialBackoff time.Duration) (audit.Backend, error) {
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w, err := loadWebhook(kubeConfigFile, groupVersion, initialBackoff)
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if err != nil {
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return nil, err
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}
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return &backend{w: w, name: PluginName}, nil
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}
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func (b *backend) Run(stopCh <-chan struct{}) error {
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return nil
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}
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func (b *backend) Shutdown() {
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// nothing to do here
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}
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func (b *backend) ProcessEvents(ev ...*auditinternal.Event) bool {
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if err := b.processEvents(ev...); err != nil {
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audit.HandlePluginError(b.String(), err, ev...)
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return false
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}
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return true
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}
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func (b *backend) processEvents(ev ...*auditinternal.Event) error {
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var list auditinternal.EventList
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for _, e := range ev {
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list.Items = append(list.Items, *e)
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}
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return b.w.WithExponentialBackoff(context.Background(), func() rest.Result {
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trace := utiltrace.New("Call Audit Events webhook",
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utiltrace.Field{"name", b.name},
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utiltrace.Field{"event-count", len(list.Items)})
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// Only log audit webhook traces that exceed a 25ms per object limit plus a 50ms
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// request overhead allowance. The high per object limit used here is primarily to
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// allow enough time for the serialization/deserialization of audit events, which
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// contain nested request and response objects plus additional event fields.
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defer trace.LogIfLong(time.Duration(50+25*len(list.Items)) * time.Millisecond)
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return b.w.RestClient.Post().Body(&list).Do()
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}).Error()
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}
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func (b *backend) String() string {
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return b.name
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}
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