Refactor filebeat connector (#12997)

The filebeat channel package wraps the publisher pipeline,
providing support for preparing custom user settings. The drawback is,
that inputs can not configure custom fields, processors, and ACK
handlers. The later is required for implementing end-to-end ACK.

This refactoring modifies the channel.Factory and channel.Connector
types, such that input authors are able to make use of all the
capabilities of the publisher pipeline.

Inputs are free to configure the PublishMode. If not set, then filebeat
defaults to guaranteed sends.

The channel.Outleter should become more similar to beat.Client in the
future, and will be eventually removed. A side effect of moving closer
to beat.Client is the removal of the filebeat/util package.
The complex shutdown handling in filebeat still prevents us from
removing channel.Outlet. The complex shutdown handling is still required
for handling the interactions between the logs input and the registrar
on shutdown.

filebeat/channel/connector.go

@@ -0,0 +1,119 @@
+// 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 channel
+
+import (
+	"github.com/elastic/beats/libbeat/beat"
+	"github.com/elastic/beats/libbeat/common"
+	"github.com/elastic/beats/libbeat/processors"
+)
+
+// ConnectorFunc is an adapter for using ordinary functions as Connector.
+type ConnectorFunc func(*common.Config, beat.ClientConfig) (Outleter, error)
+
+type pipelineConnector struct {
+	parent   *OutletFactory
+	pipeline beat.Pipeline
+}
+
+// Connect passes the cfg and the zero value of beat.ClientConfig to the underlying function.
+func (fn ConnectorFunc) Connect(cfg *common.Config) (Outleter, error) {
+	return fn(cfg, beat.ClientConfig{})
+}
+
+// ConnectWith passes the configuration and the pipeline connection setting to the underlying function.
+func (fn ConnectorFunc) ConnectWith(cfg *common.Config, clientCfg beat.ClientConfig) (Outleter, error) {
+	return fn(cfg, clientCfg)
+}
+
+func (c *pipelineConnector) Connect(cfg *common.Config) (Outleter, error) {
+	return c.ConnectWith(cfg, beat.ClientConfig{})
+}
+
+func (c *pipelineConnector) ConnectWith(cfg *common.Config, clientCfg beat.ClientConfig) (Outleter, error) {
+	config := inputOutletConfig{}
+	if err := cfg.Unpack(&config); err != nil {
+		return nil, err
+	}
+
+	var err error
+	var userProcessors beat.ProcessorList
+
+	userProcessors, err = processors.New(config.Processors)
+	if err != nil {
+		return nil, err
+	}
+
+	if lst := clientCfg.Processing.Processor; lst != nil {
+		if len(userProcessors.All()) == 0 {
+			userProcessors = lst
+		} else if orig := lst.All(); len(orig) > 0 {
+			newLst := processors.NewList(nil)
+			newLst.List = append(newLst.List, lst, userProcessors)
+			userProcessors = newLst
+		}
+	}
+
+	setOptional := func(to common.MapStr, key string, value string) {
+		if value != "" {
+			to.Put(key, value)
+		}
+	}
+
+	meta := clientCfg.Processing.Meta.Clone()
+	fields := clientCfg.Processing.Fields.Clone()
+
+	serviceType := config.ServiceType
+	if serviceType == "" {
+		serviceType = config.Module
+	}
+
+	setOptional(meta, "pipeline", config.Pipeline)
+	setOptional(fields, "fileset.name", config.Fileset)
+	setOptional(fields, "service.type", serviceType)
+	setOptional(fields, "input.type", config.Type)
+	if config.Module != "" {
+		event := common.MapStr{"module": config.Module}
+		if config.Fileset != "" {
+			event["dataset"] = config.Module + "." + config.Fileset
+		}
+		fields["event"] = event
+	}
+
+	mode := clientCfg.PublishMode
+	if mode == beat.DefaultGuarantees {
+		mode = beat.GuaranteedSend
+	}
+
+	// connect with updated configuration
+	clientCfg.PublishMode = mode
+	clientCfg.Processing.EventMetadata = config.EventMetadata
+	clientCfg.Processing.Meta = meta
+	clientCfg.Processing.Fields = fields
+	clientCfg.Processing.Processor = userProcessors
+	client, err := c.pipeline.ConnectWith(clientCfg)
+	if err != nil {
+		return nil, err
+	}
+
+	outlet := newOutlet(client, c.parent.wgEvents)
+	if c.parent.done != nil {
+		return CloseOnSignal(outlet, c.parent.done), nil
+	}
+	return outlet, nil
+}

filebeat/channel/factory.go

@@ -82,75 +82,12 @@ func NewOutletFactory(
 // Inputs and all harvesters use the same pipeline client instance.
 // This guarantees ordering between events as required by the registrar for
 // file.State updates
-func (f *OutletFactory) Create(p beat.Pipeline, cfg *common.Config, dynFields *common.MapStrPointer) (Outleter, error) {
-	config := inputOutletConfig{}
-	if err := cfg.Unpack(&config); err != nil {
-		return nil, err
-	}
-
-	processors, err := processors.New(config.Processors)
-	if err != nil {
-		return nil, err
-	}
-
-	setMeta := func(to common.MapStr, key, value string) {
-		if value != "" {
-			to[key] = value
-		}
-	}
-
-	meta := common.MapStr{}
-	setMeta(meta, "pipeline", config.Pipeline)
-
-	fields := common.MapStr{}
-	setMeta(fields, "module", config.Module)
-	if config.Module != "" && config.Fileset != "" {
-		setMeta(fields, "dataset", config.Module+"."+config.Fileset)
-	}
-	if len(fields) > 0 {
-		fields = common.MapStr{
-			"event": fields,
-		}
-	}
-	if config.Fileset != "" {
-		fields.Put("fileset.name", config.Fileset)
-	}
-	if config.ServiceType != "" {
-		fields.Put("service.type", config.ServiceType)
-	} else if config.Module != "" {
-		fields.Put("service.type", config.Module)
-	}
-	if config.Type != "" {
-		fields.Put("input.type", config.Type)
-	}
-
-	client, err := p.ConnectWith(beat.ClientConfig{
-		PublishMode: beat.GuaranteedSend,
-		Processing: beat.ProcessingConfig{
-			EventMetadata: config.EventMetadata,
-			DynamicFields: dynFields,
-			Meta:          meta,
-			Fields:        fields,
-			Processor:     processors,
-		},
-		Events: f.eventer,
-	})
-	if err != nil {
-		return nil, err
-	}
-
-	outlet := newOutlet(client, f.wgEvents)
-	if f.done != nil {
-		return CloseOnSignal(outlet, f.done), nil
-	}
-	return outlet, nil
+func (f *OutletFactory) Create(p beat.Pipeline) Connector {
+	return &pipelineConnector{parent: f, pipeline: p}
 }
 
-func (*clientEventer) Closing()   {}
-func (*clientEventer) Closed()    {}
-func (*clientEventer) Published() {}
-
-func (c *clientEventer) FilteredOut(_ beat.Event) {}
-func (c *clientEventer) DroppedOnPublish(_ beat.Event) {
-	c.wgEvents.Done()
-}
+func (e *clientEventer) Closing()                        {}
+func (e *clientEventer) Closed()                         {}
+func (e *clientEventer) Published()                      {}
+func (e *clientEventer) FilteredOut(evt beat.Event)      {}
+func (e *clientEventer) DroppedOnPublish(evt beat.Event) { e.wgEvents.Done() }

filebeat/channel/interface.go

@@ -18,20 +18,23 @@
 package channel
 
 import (
-	"github.com/elastic/beats/filebeat/util"
 	"github.com/elastic/beats/libbeat/beat"
 	"github.com/elastic/beats/libbeat/common"
 )
 
 // Factory is used to create a new Outlet instance
-type Factory func(beat.Pipeline, *common.Config, *common.MapStrPointer) (Outleter, error)
+type Factory func(beat.Pipeline) Connector
 
 // Connector creates an Outlet connecting the event publishing with some internal pipeline.
-type Connector func(*common.Config, *common.MapStrPointer) (Outleter, error)
+// type Connector func(*common.Config, *common.MapStrPointer) (Outleter, error)
+type Connector interface {
+	Connect(*common.Config) (Outleter, error)
+	ConnectWith(*common.Config, beat.ClientConfig) (Outleter, error)
+}
 
 // Outleter is the outlet for an input
 type Outleter interface {
 	Close() error
 	Done() <-chan struct{}
-	OnEvent(data *util.Data) bool
+	OnEvent(beat.Event) bool
 }

filebeat/channel/outlet.go

@@ -18,7 +18,6 @@
 package channel
 
 import (
-	"github.com/elastic/beats/filebeat/util"
 	"github.com/elastic/beats/libbeat/beat"
 	"github.com/elastic/beats/libbeat/common/atomic"
 )
@@ -53,16 +52,11 @@ func (o *outlet) Done() <-chan struct{} {
 	return o.done
 }
 
-func (o *outlet) OnEvent(d *util.Data) bool {
+func (o *outlet) OnEvent(event beat.Event) bool {
 	if !o.isOpen.Load() {
 		return false
 	}
 
-	event := d.GetEvent()
-	if d.HasState() {
-		event.Private = d.GetState()
-	}
-
 	if o.wg != nil {
 		o.wg.Add(1)
 	}

filebeat/channel/util.go

@@ -20,32 +20,23 @@ package channel
 import (
 	"sync"
 
-	"github.com/elastic/beats/filebeat/util"
 	"github.com/elastic/beats/libbeat/beat"
-	"github.com/elastic/beats/libbeat/common"
 )
 
 type subOutlet struct {
 	done      chan struct{}
-	ch        chan *util.Data
+	ch        chan beat.Event
 	res       chan bool
 	mutex     sync.Mutex
 	closeOnce sync.Once
 }
 
-// ConnectTo creates a new Connector, combining a beat.Pipeline with an outlet Factory.
-func ConnectTo(pipeline beat.Pipeline, factory Factory) Connector {
-	return func(cfg *common.Config, m *common.MapStrPointer) (Outleter, error) {
-		return factory(pipeline, cfg, m)
-	}
-}
-
 // SubOutlet create a sub-outlet, which can be closed individually, without closing the
 // underlying outlet.
 func SubOutlet(out Outleter) Outleter {
 	s := &subOutlet{
 		done: make(chan struct{}),
-		ch:   make(chan *util.Data),
+		ch:   make(chan beat.Event),
 		res:  make(chan bool, 1),
 	}
 
@@ -75,7 +66,7 @@ func (o *subOutlet) Done() <-chan struct{} {
 	return o.done
 }
 
-func (o *subOutlet) OnEvent(d *util.Data) bool {
+func (o *subOutlet) OnEvent(event beat.Event) bool {
 
 	o.mutex.Lock()
 	defer o.mutex.Unlock()
@@ -89,7 +80,7 @@ func (o *subOutlet) OnEvent(d *util.Data) bool {
 	case <-o.done:
 		return false
 
-	case o.ch <- d:
+	case o.ch <- event:
 		select {
 		case <-o.done:
 

filebeat/channel/util_test.go

@@ -22,7 +22,7 @@ import (
 
 	"github.com/stretchr/testify/assert"
 
-	"github.com/elastic/beats/filebeat/util"
+	"github.com/elastic/beats/libbeat/beat"
 	"github.com/elastic/beats/libbeat/tests/resources"
 )
 
@@ -31,7 +31,7 @@ type dummyOutletter struct {
 	c      chan struct{}
 }
 
-func (o *dummyOutletter) OnEvent(event *util.Data) bool {
+func (o *dummyOutletter) OnEvent(event beat.Event) bool {
 	return true
 }
 

filebeat/crawler/crawler.go

@@ -117,7 +117,7 @@ func (c *Crawler) startInput(
 		return nil
 	}
 
-	connector := channel.ConnectTo(pipeline, c.out)
+	connector := c.out(pipeline)
 	p, err := input.New(config, connector, c.beatDone, states, nil)
 	if err != nil {
 		return fmt.Errorf("Error while initializing input: %s", err)

filebeat/fileset/factory.go

@@ -98,7 +98,7 @@ func (f *Factory) Create(p beat.Pipeline, c *common.Config, meta *common.MapStrP
 	}
 
 	inputs := make([]*input.Runner, len(pConfigs))
-	connector := channel.ConnectTo(p, f.outlet)
+	connector := f.outlet(p)
 	for i, pConfig := range pConfigs {
 		inputs[i], err = input.New(pConfig, connector, f.beatDone, f.registrar.GetStates(), meta)
 		if err != nil {

filebeat/harvester/forwarder.go

@@ -20,13 +20,13 @@ package harvester
 import (
 	"errors"
 
-	"github.com/elastic/beats/filebeat/util"
+	"github.com/elastic/beats/libbeat/beat"
 	"github.com/elastic/beats/libbeat/logp"
 )
 
 // Outlet interface is used for forwarding events
 type Outlet interface {
-	OnEvent(data *util.Data) bool
+	OnEvent(data beat.Event) bool
 }
 
 // Forwarder contains shared options between all harvesters needed to forward events
@@ -46,8 +46,8 @@ func NewForwarder(outlet Outlet) *Forwarder {
 
 // Send updates the input state and sends the event to the spooler
 // All state updates done by the input itself are synchronous to make sure no states are overwritten
-func (f *Forwarder) Send(data *util.Data) error {
-	ok := f.Outlet.OnEvent(data)
+func (f *Forwarder) Send(event beat.Event) error {
+	ok := f.Outlet.OnEvent(event)
 	if !ok {
 		logp.Info("Input outlet closed")
 		return errors.New("input outlet closed")