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client.go
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client.go
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// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 elasticsearch
import (
"context"
"errors"
"fmt"
"net/http"
"strings"
"time"
"go.elastic.co/apm/v2"
"github.com/elastic/beats/v7/libbeat/beat"
"github.com/elastic/beats/v7/libbeat/beat/events"
"github.com/elastic/beats/v7/libbeat/esleg/eslegclient"
"github.com/elastic/beats/v7/libbeat/outputs"
"github.com/elastic/beats/v7/libbeat/outputs/outil"
"github.com/elastic/beats/v7/libbeat/publisher"
"github.com/elastic/elastic-agent-libs/logp"
"github.com/elastic/elastic-agent-libs/mapstr"
"github.com/elastic/elastic-agent-libs/testing"
"github.com/elastic/elastic-agent-libs/version"
)
var (
errPayloadTooLarge = errors.New("the bulk payload is too large for the server. Consider to adjust `http.max_content_length` parameter in Elasticsearch or `bulk_max_size` in the beat. The batch has been dropped")
ErrTooOld = errors.New("Elasticsearch is too old. Please upgrade the instance. If you would like to connect to older instances set output.elasticsearch.allow_older_versions to true.")
)
// Client is an elasticsearch client.
type Client struct {
conn eslegclient.Connection
indexSelector outputs.IndexSelector
pipelineSelector *outil.Selector
observer outputs.Observer
// If deadLetterIndex is set, events with bulk-ingest errors will be
// forwarded to this index. Otherwise, they will be dropped.
deadLetterIndex string
log *logp.Logger
}
// clientSettings contains the settings for a client.
type clientSettings struct {
connection eslegclient.ConnectionSettings
indexSelector outputs.IndexSelector
pipelineSelector *outil.Selector
// The metrics observer from the clientSettings, or a no-op placeholder if
// none is provided. This variable is always non-nil for a client created
// via NewClient.
observer outputs.Observer
// If deadLetterIndex is set, events with bulk-ingest errors will be
// forwarded to this index. Otherwise, they will be dropped.
deadLetterIndex string
}
type bulkResultStats struct {
acked int // number of events ACKed by Elasticsearch
duplicates int // number of events failed with `create` due to ID already being indexed
fails int // number of events with retryable failures.
nonIndexable int // number of events with permanent failures.
deadLetter int // number of failed events ingested to the dead letter index.
tooMany int // number of events receiving HTTP 429 Too Many Requests
}
type bulkResult struct {
// A connection-level error if the request couldn't be sent or the response
// couldn't be read. This error is returned from (*Client).Publish to signal
// to the pipeline that this output worker needs to be reconnected before the
// next Publish call.
connErr error
// The array of events sent via bulk request. This excludes any events that
// had encoding errors while assembling the request.
events []publisher.Event
// The http status returned by the bulk request.
status int
// The API response from Elasticsearch.
response eslegclient.BulkResponse
}
const (
defaultEventType = "doc"
)
// Flags passed with the Bulk API request: we filter the response to include
// only the fields we need for checking request/item state.
var bulkRequestParams = map[string]string{
"filter_path": "errors,items.*.error,items.*.status",
}
// NewClient instantiates a new client.
func NewClient(
s clientSettings,
onConnect *callbacksRegistry,
) (*Client, error) {
pipeline := s.pipelineSelector
if pipeline != nil && pipeline.IsEmpty() {
pipeline = nil
}
conn, err := eslegclient.NewConnection(s.connection)
if err != nil {
return nil, err
}
conn.OnConnectCallback = func() error {
globalCallbackRegistry.mutex.Lock()
defer globalCallbackRegistry.mutex.Unlock()
for _, callback := range globalCallbackRegistry.callbacks {
err := callback(conn)
if err != nil {
return err
}
}
if onConnect != nil {
onConnect.mutex.Lock()
defer onConnect.mutex.Unlock()
for _, callback := range onConnect.callbacks {
err := callback(conn)
if err != nil {
return err
}
}
}
return nil
}
// Make sure there's a non-nil obser
observer := s.observer
if observer == nil {
observer = outputs.NewNilObserver()
}
client := &Client{
conn: *conn,
indexSelector: s.indexSelector,
pipelineSelector: pipeline,
observer: observer,
deadLetterIndex: s.deadLetterIndex,
log: logp.NewLogger("elasticsearch"),
}
return client, nil
}
// Clone clones a client.
func (client *Client) Clone() *Client {
// when cloning the connection callback and params are not copied. A
// client's close is for example generated for topology-map support. With params
// most likely containing the ingest node pipeline and default callback trying to
// create install a template, we don't want these to be included in the clone.
connection := eslegclient.ConnectionSettings{
URL: client.conn.URL,
Beatname: client.conn.Beatname,
Kerberos: client.conn.Kerberos,
Username: client.conn.Username,
Password: client.conn.Password,
APIKey: client.conn.APIKey,
Parameters: nil, // XXX: do not pass params?
Headers: client.conn.Headers,
CompressionLevel: client.conn.CompressionLevel,
OnConnectCallback: nil,
Observer: nil,
EscapeHTML: false,
Transport: client.conn.Transport,
}
// Without the following nil check on proxyURL, a nil Proxy field will try
// reloading proxy settings from the environment instead of leaving them
// empty.
client.conn.Transport.Proxy.Disable = client.conn.Transport.Proxy.URL == nil
c, _ := NewClient(
clientSettings{
connection: connection,
indexSelector: client.indexSelector,
pipelineSelector: client.pipelineSelector,
deadLetterIndex: client.deadLetterIndex,
},
nil, // XXX: do not pass connection callback?
)
return c
}
func (client *Client) Publish(ctx context.Context, batch publisher.Batch) error {
span, ctx := apm.StartSpan(ctx, "publishEvents", "output")
defer span.End()
span.Context.SetLabel("events_original", len(batch.Events()))
client.observer.NewBatch(len(batch.Events()))
// Create and send the bulk request.
bulkResult := client.doBulkRequest(ctx, batch)
span.Context.SetLabel("events_encoded", len(bulkResult.events))
if bulkResult.connErr != nil {
// If there was a connection-level error there is no per-item response,
// handle it and return.
return client.handleBulkResultError(ctx, batch, bulkResult)
}
span.Context.SetLabel("events_published", len(bulkResult.events))
// At this point we have an Elasticsearch response for our request,
// check and report the per-item results.
eventsToRetry, stats := client.bulkCollectPublishFails(bulkResult)
stats.reportToObserver(client.observer)
if len(eventsToRetry) > 0 {
span.Context.SetLabel("events_failed", len(eventsToRetry))
batch.RetryEvents(eventsToRetry)
} else {
batch.ACK()
}
return nil
}
// Encode a batch's events into a bulk publish request, send the request to
// Elasticsearch, and return the resulting metadata.
// Reports the network request latency to the client's metrics observer.
// The events list in the result will be shorter than the original batch if
// some events couldn't be encoded. In this case, the removed events will
// be reported to the Client's metrics observer via PermanentErrors.
func (client *Client) doBulkRequest(
ctx context.Context,
batch publisher.Batch,
) bulkResult {
var result bulkResult
rawEvents := batch.Events()
// encode events into bulk request buffer, dropping failed elements from
// events slice
resultEvents, bulkItems := client.bulkEncodePublishRequest(client.conn.GetVersion(), rawEvents)
result.events = resultEvents
client.observer.PermanentErrors(len(rawEvents) - len(resultEvents))
// If we encoded any events, send the network request.
if len(result.events) > 0 {
begin := time.Now()
result.status, result.response, result.connErr =
client.conn.Bulk(ctx, "", "", bulkRequestParams, bulkItems)
if result.connErr == nil {
duration := time.Since(begin)
client.observer.ReportLatency(duration)
client.log.Debugf(
"doBulkRequest: %d events have been sent to elasticsearch in %v.",
len(result.events), duration)
}
}
return result
}
func (client *Client) handleBulkResultError(
ctx context.Context, batch publisher.Batch, bulkResult bulkResult,
) error {
if bulkResult.status == http.StatusRequestEntityTooLarge {
if batch.SplitRetry() {
// Report that we split a batch
client.observer.BatchSplit()
client.observer.RetryableErrors(len(bulkResult.events))
} else {
// If the batch could not be split, there is no option left but
// to drop it and log the error state.
batch.Drop()
client.observer.PermanentErrors(len(bulkResult.events))
client.log.Error(errPayloadTooLarge)
}
// Don't propagate a too-large error since it doesn't indicate a problem
// with the connection.
return nil
}
err := apm.CaptureError(ctx, fmt.Errorf("failed to perform any bulk index operations: %w", bulkResult.connErr))
err.Send()
client.log.Error(err)
if len(bulkResult.events) > 0 {
// At least some events failed, retry them
batch.RetryEvents(bulkResult.events)
} else {
// All events were sent successfully
batch.ACK()
}
client.observer.RetryableErrors(len(bulkResult.events))
return bulkResult.connErr
}
// bulkEncodePublishRequest encodes all bulk requests and returns slice of events
// successfully added to the list of bulk items and the list of bulk items.
func (client *Client) bulkEncodePublishRequest(version version.V, data []publisher.Event) ([]publisher.Event, []interface{}) {
okEvents := data[:0]
bulkItems := []interface{}{}
for i := range data {
if data[i].EncodedEvent == nil {
client.log.Error("Elasticsearch output received unencoded publisher.Event")
continue
}
event := data[i].EncodedEvent.(*encodedEvent)
if event.err != nil {
// This means there was an error when encoding the event and it isn't
// ingestable, so report the error and continue.
client.log.Error(event.err)
continue
}
meta, err := client.createEventBulkMeta(version, event)
if err != nil {
client.log.Errorf("Failed to encode event meta data: %+v", err)
continue
}
if event.opType == events.OpTypeDelete {
// We don't include the event source in a bulk DELETE
bulkItems = append(bulkItems, meta)
} else {
// Wrap the encoded event in a RawEncoding so the Elasticsearch client
// knows not to re-encode it
bulkItems = append(bulkItems, meta, eslegclient.RawEncoding{Encoding: event.encoding})
}
okEvents = append(okEvents, data[i])
}
return okEvents, bulkItems
}
func (client *Client) createEventBulkMeta(version version.V, event *encodedEvent) (interface{}, error) {
eventType := ""
if version.Major < 7 {
eventType = defaultEventType
}
meta := eslegclient.BulkMeta{
Index: event.index,
DocType: eventType,
Pipeline: event.pipeline,
ID: event.id,
}
if event.opType == events.OpTypeDelete {
if event.id != "" {
return eslegclient.BulkDeleteAction{Delete: meta}, nil
} else {
return nil, fmt.Errorf("%s %s requires _id", events.FieldMetaOpType, events.OpTypeDelete)
}
}
if event.id != "" || version.Major > 7 || (version.Major == 7 && version.Minor >= 5) {
if event.opType == events.OpTypeIndex {
return eslegclient.BulkIndexAction{Index: meta}, nil
}
return eslegclient.BulkCreateAction{Create: meta}, nil
}
return eslegclient.BulkIndexAction{Index: meta}, nil
}
func getPipeline(event *beat.Event, defaultSelector *outil.Selector) (string, error) {
if event.Meta != nil {
pipeline, err := events.GetMetaStringValue(*event, events.FieldMetaPipeline)
if errors.Is(err, mapstr.ErrKeyNotFound) {
return "", nil
}
if err != nil {
return "", errors.New("pipeline metadata is no string")
}
return strings.ToLower(pipeline), nil
}
if defaultSelector != nil {
return defaultSelector.Select(event)
}
return "", nil
}
// bulkCollectPublishFails checks per item errors returning all events
// to be tried again due to error code returned for that items. If indexing an
// event failed due to some error in the event itself (e.g. does not respect mapping),
// the event will be dropped.
// Each of the events will be reported in the returned stats as exactly one of
// acked, duplicates, fails, nonIndexable, or deadLetter.
func (client *Client) bulkCollectPublishFails(bulkResult bulkResult) ([]publisher.Event, bulkResultStats) {
events := bulkResult.events
if len(bulkResult.events) == 0 {
// No events to process
return nil, bulkResultStats{}
}
if bulkResult.status != 200 {
return events, bulkResultStats{fails: len(events)}
}
reader := newJSONReader(bulkResult.response)
if err := bulkReadToItems(reader); err != nil {
client.log.Errorf("failed to parse bulk response: %v", err.Error())
return events, bulkResultStats{fails: len(events)}
}
count := len(events)
eventsToRetry := events[:0]
stats := bulkResultStats{}
for i := 0; i < count; i++ {
itemStatus, itemMessage, err := bulkReadItemStatus(client.log, reader)
if err != nil {
// The response json is invalid, mark the remaining events for retry.
stats.fails += count - i
eventsToRetry = append(eventsToRetry, events[i:]...)
break
}
if client.applyItemStatus(events[i], itemStatus, itemMessage, &stats) {
eventsToRetry = append(eventsToRetry, events[i])
client.log.Debugf("Bulk item insert failed (i=%v, status=%v): %s", i, itemStatus, itemMessage)
}
}
return eventsToRetry, stats
}
// applyItemStatus processes the ingestion status of one event from a bulk request.
// Returns true if the item should be retried.
// In the provided bulkResultStats, applyItemStatus increments exactly one of:
// acked, duplicates, deadLetter, fails, nonIndexable.
func (client *Client) applyItemStatus(
event publisher.Event,
itemStatus int,
itemMessage []byte,
stats *bulkResultStats,
) bool {
encodedEvent := event.EncodedEvent.(*encodedEvent)
if itemStatus < 300 {
if encodedEvent.deadLetter {
// This was ingested into the dead letter index, not the original target
stats.deadLetter++
} else {
stats.acked++
}
return false // no retry needed
}
if itemStatus == 409 {
// 409 is used to indicate there is already an event with the same ID, or
// with identical Time Series Data Stream dimensions when TSDS is active.
stats.duplicates++
return false // no retry needed
}
if itemStatus == http.StatusTooManyRequests {
stats.fails++
stats.tooMany++
return true
}
if itemStatus < 500 {
// hard failure, apply policy action
if encodedEvent.deadLetter {
// Fatal error while sending an already-failed event to the dead letter
// index, drop.
client.log.Errorf("Can't deliver to dead letter index event (status=%v). Look at the event log to view the event and cause.", itemStatus)
client.log.Errorw(fmt.Sprintf("Can't deliver to dead letter index event %#v (status=%v): %s", event, itemStatus, itemMessage), logp.TypeKey, logp.EventType)
stats.nonIndexable++
return false
}
if client.deadLetterIndex == "" {
// Fatal error and no dead letter index, drop.
client.log.Warnf("Cannot index event (status=%v): dropping event! Look at the event log to view the event and cause.", itemStatus)
client.log.Warnw(fmt.Sprintf("Cannot index event %#v (status=%v): %s, dropping event!", event, itemStatus, itemMessage), logp.TypeKey, logp.EventType)
stats.nonIndexable++
return false
}
// Send this failure to the dead letter index and "retry".
// We count this as a "retryable failure", and then if the dead letter
// ingestion succeeds it is counted in the "deadLetter" counter
// rather than the "acked" counter.
client.log.Warnf("Cannot index event (status=%v), trying dead letter index. Look at the event log to view the event and cause.", itemStatus)
client.log.Warnw(fmt.Sprintf("Cannot index event %#v (status=%v): %s, trying dead letter index", event, itemStatus, itemMessage), logp.TypeKey, logp.EventType)
encodedEvent.setDeadLetter(client.deadLetterIndex, itemStatus, string(itemMessage))
}
// Everything else gets retried.
stats.fails++
return true
}
func (client *Client) Connect() error {
return client.conn.Connect()
}
func (client *Client) Close() error {
return client.conn.Close()
}
func (client *Client) String() string {
return "elasticsearch(" + client.conn.URL + ")"
}
func (client *Client) Test(d testing.Driver) {
client.conn.Test(d)
}
func (stats bulkResultStats) reportToObserver(ob outputs.Observer) {
ob.AckedEvents(stats.acked)
ob.RetryableErrors(stats.fails)
ob.PermanentErrors(stats.nonIndexable)
ob.DuplicateEvents(stats.duplicates)
ob.DeadLetterEvents(stats.deadLetter)
ob.ErrTooMany(stats.tooMany)
}