filestream: validate input id on startup

CHANGELOG.next.asciidoc

@@ -50,8 +50,8 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 - Remove deprecated awscloudwatch field from Filebeat. {pull}41089[41089]
 - The performance of ingesting SQS data with the S3 input has improved by up to 60x for queues with many small events. `max_number_of_messages` config for SQS mode is now ignored, as the new design no longer needs a manual cap on messages. Instead, use `number_of_workers` to scale ingestion rate in both S3 and SQS modes. The increased efficiency may increase network bandwidth consumption, which can be throttled by lowering `number_of_workers`. It may also increase number of events stored in memory, which can be throttled by lowering the configured size of the internal queue. {pull}40699[40699]
 - Fixes filestream logging the error "filestream input with ID 'ID' already exists, this will lead to data duplication[...]" on Kubernetes when using autodiscover. {pull}41585[41585]
-
 - Add kafka compression support for ZSTD.
+- Filebeat fails to start if there is any input with a duplicated ID. It logs the duplicated IDs and the offending inputs configurations. {pull}41731[41731]
 
 *Heartbeat*
 

filebeat/beater/filebeat.go

@@ -32,6 +32,7 @@ import (
 	"github.com/elastic/beats/v7/filebeat/fileset"
 	_ "github.com/elastic/beats/v7/filebeat/include"
 	"github.com/elastic/beats/v7/filebeat/input"
+	"github.com/elastic/beats/v7/filebeat/input/filestream"
 	"github.com/elastic/beats/v7/filebeat/input/filestream/takeover"
 	v2 "github.com/elastic/beats/v7/filebeat/input/v2"
 	"github.com/elastic/beats/v7/filebeat/input/v2/compat"
@@ -291,6 +292,11 @@ func (fb *Filebeat) Run(b *beat.Beat) error {
 	}
 	defer stateStore.Close()
 
+	err = filestream.ValidateInputIDs(config.Inputs, logp.NewLogger("input.filestream"))
+	if err != nil {
+		logp.Err("invalid filestream configuration: %+v", err)
+		return err
+	}
 	err = processLogInputTakeOver(stateStore, config)
 	if err != nil {
 		logp.Err("Failed to attempt filestream state take over: %+v", err)

filebeat/input/filestream/config.go

@@ -19,6 +19,7 @@ package filestream
 
 import (
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/dustin/go-humanize"
@@ -27,6 +28,7 @@ import (
 	"github.com/elastic/beats/v7/libbeat/reader/parser"
 	"github.com/elastic/beats/v7/libbeat/reader/readfile"
 	conf "github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/logp"
 )
 
 // Config stores the options of a file stream.
@@ -142,3 +144,60 @@ func (c *config) Validate() error {
 
 	return nil
 }
+
+// ValidateInputIDs checks all filestream inputs to ensure all input IDs are
+// unique. If there is a duplicated ID, it logs an error containing the offending
+// input configurations and returns an error containing the duplicated IDs.
+// A single empty ID is a valid ID as it's unique, however multiple empty IDs
+// are not unique and are therefore are treated as any other duplicated ID.
+func ValidateInputIDs(inputs []*conf.C, logger *logp.Logger) error {
+	duplicatedConfigs := make(map[string][]*conf.C)
+	var duplicates []string
+	for _, input := range inputs {
+		fsInput := struct {
+			ID   string `config:"id"`
+			Type string `config:"type"`
+		}{}
+		err := input.Unpack(&fsInput)
+		if err != nil {
+			return fmt.Errorf("failed to unpack filestream input configuration: %w", err)
+		}
+		if fsInput.Type == "filestream" {
+			duplicatedConfigs[fsInput.ID] = append(duplicatedConfigs[fsInput.ID], input)
+			// we just need to collect the duplicated IDs once, therefore collect
+			// it only the first time we see a duplicated ID.
+			if len(duplicatedConfigs[fsInput.ID]) == 2 {
+				duplicates = append(duplicates, fsInput.ID)
+			}
+		}
+	}
+
+	if len(duplicates) != 0 {
+		jsonDupCfg := collectOffendingInputs(duplicates, duplicatedConfigs)
+		logger.Errorw("filestream inputs with duplicated IDs", "inputs", jsonDupCfg)
+		var quotedDuplicates []string
+		for _, dup := range duplicates {
+			quotedDuplicates = append(quotedDuplicates, fmt.Sprintf("%q", dup))
+		}
+		return fmt.Errorf("filestream inputs validation error: filestream inputs with duplicated IDs: %v", strings.Join(quotedDuplicates, ","))
+	}
+
+	return nil
+}
+
+func collectOffendingInputs(duplicates []string, ids map[string][]*conf.C) []map[string]interface{} {
+	var cfgs []map[string]interface{}
+
+	for _, id := range duplicates {
+		for _, dupcfgs := range ids[id] {
+			toJson := map[string]interface{}{}
+			err := dupcfgs.Unpack(&toJson)
+			if err != nil {
+				toJson[id] = fmt.Sprintf("failed to unpack config: %v", err)
+			}
+			cfgs = append(cfgs, toJson)
+		}
+	}
+
+	return cfgs
+}

filebeat/input/filestream/config_test.go

@@ -18,9 +18,16 @@
 package filestream
 
 import (
+	"encoding/json"
+	"strings"
 	"testing"
 
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"go.uber.org/zap/zaptest/observer"
+
+	conf "github.com/elastic/elastic-agent-libs/config"
+	"github.com/elastic/elastic-agent-libs/logp"
 )
 
 func TestConfigValidate(t *testing.T) {
@@ -30,3 +37,186 @@ func TestConfigValidate(t *testing.T) {
 		require.Error(t, err)
 	})
 }
+
+func TestValidateInputIDs(t *testing.T) {
+	tcs := []struct {
+		name       string
+		cfg        []string
+		assertErr  func(t *testing.T, err error)
+		assertLogs func(t *testing.T, buff *observer.ObservedLogs)
+	}{
+		{
+			name: "empty config",
+			cfg:  []string{""},
+			assertErr: func(t *testing.T, err error) {
+				assert.NoError(t, err, "empty config should not return an error")
+			},
+		},
+		{
+			name: "one empty ID is allowed",
+			cfg: []string{`
+type: filestream
+`, `
+type: filestream
+id: some-id-1
+`, `
+type: filestream
+id: some-id-2
+`,
+			},
+			assertErr: func(t *testing.T, err error) {
+				assert.NoError(t, err, "one empty id is allowed")
+			},
+		},
+		{
+			name: "duplicated empty ID",
+			cfg: []string{`
+type: filestream
+paths:
+  - "/tmp/empty-1"
+`, `
+type: filestream
+paths:
+  - "/tmp/empty-2"
+`, `
+type: filestream
+id: unique-id-1
+`, `
+type: filestream
+id: unique-id-2
+`, `
+type: filestream
+id: unique-ID
+`,
+			},
+			assertErr: func(t *testing.T, err error) {
+				assert.ErrorContains(t, err, `filestream inputs with duplicated IDs: ""`)
+
+			},
+			assertLogs: func(t *testing.T, obs *observer.ObservedLogs) {
+				want := `[{"paths":["/tmp/empty-1"],"type":"filestream"},{"paths":["/tmp/empty-2"],"type":"filestream"}]`
+
+				logs := obs.TakeAll()
+				require.Len(t, logs, 1, "there should be only one log entry")
+
+				got, err := json.Marshal(logs[0].ContextMap()["inputs"])
+				require.NoError(t, err, "could not marshal duplicated IDs inputs")
+				assert.Equal(t, want, string(got))
+			},
+		}, {
+			name: "duplicated IDs",
+			cfg: []string{`
+type: filestream
+id: duplicated-id-1
+`, `
+type: filestream
+id: duplicated-id-1
+`, `
+type: filestream
+id: duplicated-id-2
+`, `
+type: filestream
+id: duplicated-id-2
+`, `
+type: filestream
+id: duplicated-id-2
+`, `
+type: filestream
+id: unique-ID
+`,
+			},
+			assertErr: func(t *testing.T, err error) {
+				assert.ErrorContains(t, err, "filestream inputs with duplicated IDs")
+				assert.ErrorContains(t, err, "duplicated-id-1")
+				assert.ErrorContains(t, err, "duplicated-id-2")
+				assert.Equal(t, strings.Count(err.Error(), "duplicated-id-1"), 1, "each IDs should appear only once")
+				assert.Equal(t, strings.Count(err.Error(), "duplicated-id-2"), 1, "each IDs should appear only once")
+
+			},
+			assertLogs: func(t *testing.T, obs *observer.ObservedLogs) {
+				want := `[{"id":"duplicated-id-1","type":"filestream"},{"id":"duplicated-id-1","type":"filestream"},{"id":"duplicated-id-2","type":"filestream"},{"id":"duplicated-id-2","type":"filestream"},{"id":"duplicated-id-2","type":"filestream"}]`
+
+				logs := obs.TakeAll()
+				require.Len(t, logs, 1, "there should be only one log entry")
+
+				got, err := json.Marshal(logs[0].ContextMap()["inputs"])
+				require.NoError(t, err, "could not marshal duplicated IDs inputs")
+				assert.Equal(t, want, string(got))
+			},
+		},
+		{
+			name: "duplicated IDs and empty ID",
+			cfg: []string{`
+type: filestream
+`, `
+type: filestream
+`, `
+type: filestream
+id: duplicated-id-1
+`, `
+type: filestream
+id: duplicated-id-1
+`, `
+type: filestream
+id: duplicated-id-2
+`, `
+type: filestream
+id: duplicated-id-2
+`, `
+type: filestream
+id: unique-ID
+`,
+			},
+			assertErr: func(t *testing.T, err error) {
+				assert.ErrorContains(t, err, "filestream inputs with duplicated IDs")
+			},
+			assertLogs: func(t *testing.T, obs *observer.ObservedLogs) {
+				want := `[{"type":"filestream"},{"type":"filestream"},{"id":"duplicated-id-1","type":"filestream"},{"id":"duplicated-id-1","type":"filestream"},{"id":"duplicated-id-2","type":"filestream"},{"id":"duplicated-id-2","type":"filestream"}]`
+
+				logs := obs.TakeAll()
+				require.Len(t, logs, 1, "there should be only one log entry")
+
+				got, err := json.Marshal(logs[0].ContextMap()["inputs"])
+				require.NoError(t, err, "could not marshal duplicated IDs inputs")
+				assert.Equal(t, want, string(got))
+
+			},
+		},
+		{
+			name: "only unique IDs",
+			cfg: []string{`
+type: filestream
+id: unique-id-1
+`, `
+type: filestream
+id: unique-id-2
+`, `
+type: filestream
+id: unique-id-3
+`,
+			},
+			assertErr: func(t *testing.T, err error) {
+				assert.NoError(t, err, "only unique IDs should not return an error")
+			},
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			var inputs []*conf.C
+			for _, c := range tc.cfg {
+				cfg, err := conf.NewConfigFrom(c)
+				require.NoError(t, err, "could not create input configuration")
+				inputs = append(inputs, cfg)
+			}
+			err := logp.DevelopmentSetup(logp.ToObserverOutput())
+			require.NoError(t, err, "could not setup log for development")
+
+			err = ValidateInputIDs(inputs, logp.L())
+			tc.assertErr(t, err)
+			if tc.assertLogs != nil {
+				tc.assertLogs(t, logp.ObserverLogs())
+			}
+		})
+	}
+}