Fix Stringer implementation of fingerprint processor

CHANGELOG-developer.next.asciidoc

@@ -86,6 +86,7 @@ The list below covers the major changes between 7.0.0-rc2 and main only.
 - Fix ingest pipeline for panw module to parse url scheme correctly {pull}35757[35757]
 - Renamed an httpjson input metric to follow naming conventions. `httpjson_interval_pages_total` was renamed to `httpjson_interval_pages` because the `_total` suffix is reserved for counters. {issue}35933[35933] {pull}36169[36169]
 - Fixed some race conditions in tests {pull}36185[36185]
+- Fix Stringer implementation of fingerprint processor {issue}35174[35174]
 
 ==== Added
 

libbeat/processors/fingerprint/config.go

@@ -17,13 +17,15 @@
 
 package fingerprint
 
+import "encoding/json"
+
 // Config for fingerprint processor.
 type Config struct {
-	Method        hashMethod     `config:"method"`                     // Hash function to use for fingerprinting
-	Fields        []string       `config:"fields" validate:"required"` // Source fields to compute fingerprint from
-	TargetField   string         `config:"target_field"`               // Target field for the fingerprint
-	Encoding      encodingMethod `config:"encoding"`                   // Encoding to use for target field value
-	IgnoreMissing bool           `config:"ignore_missing"`             // Ignore missing fields?
+	Method        namedHashMethod     `config:"method"`                     // Hash function to use for fingerprinting
+	Fields        []string            `config:"fields" validate:"required"` // Source fields to compute fingerprint from
+	TargetField   string              `config:"target_field"`               // Target field for the fingerprint
+	Encoding      namedEncodingMethod `config:"encoding"`                   // Encoding to use for target field value
+	IgnoreMissing bool                `config:"ignore_missing"`             // Ignore missing fields?
 }
 
 func defaultConfig() Config {
@@ -34,3 +36,16 @@ func defaultConfig() Config {
 		IgnoreMissing: false,
 	}
 }
+
+func (c *Config) MarshalJSON() ([]byte, error) {
+	type Alias Config
+	return json.Marshal(&struct {
+		Method   string
+		Encoding string
+		*Alias
+	}{
+		Method:   c.Method.Name,
+		Encoding: c.Encoding.Name,
+		Alias:    (*Alias)(c),
+	})
+}

libbeat/processors/fingerprint/encode.go

@@ -24,16 +24,26 @@ import (
 	"strings"
 )
 
+type namedEncodingMethod struct {
+	Name   string
+	Encode encodingMethod
+}
 type encodingMethod func([]byte) string
 
-var encodings = map[string]encodingMethod{
-	"hex":    hex.EncodeToString,
-	"base32": base32.StdEncoding.EncodeToString,
-	"base64": base64.StdEncoding.EncodeToString,
+var encodings = map[string]namedEncodingMethod{}
+
+func init() {
+	for _, e := range []namedEncodingMethod{
+		{Name: "hex", Encode: hex.EncodeToString},
+		{Name: "base32", Encode: base32.StdEncoding.EncodeToString},
+		{Name: "base64", Encode: base64.StdEncoding.EncodeToString},
+	} {
+		encodings[e.Name] = e
+	}
 }
 
 // Unpack creates the encodingMethod from the given string
-func (e *encodingMethod) Unpack(str string) error {
+func (e *namedEncodingMethod) Unpack(str string) error {
 	str = strings.ToLower(str)
 
 	m, found := encodings[str]

libbeat/processors/fingerprint/fingerprint.go

@@ -60,7 +60,7 @@ func New(cfg *config.C) (beat.Processor, error) {
 
 	p := &fingerprint{
 		config: config,
-		hash:   config.Method,
+		hash:   config.Method.Hash,
 		fields: fields,
 	}
 
@@ -75,7 +75,7 @@ func (p *fingerprint) Run(event *beat.Event) (*beat.Event, error) {
 		return nil, makeErrComputeFingerprint(err)
 	}
 
-	encodedHash := p.config.Encoding(hashFn.Sum(nil))
+	encodedHash := p.config.Encoding.Encode(hashFn.Sum(nil))
 
 	if _, err := event.PutValue(p.config.TargetField, encodedHash); err != nil {
 		return nil, makeErrComputeFingerprint(err)
@@ -85,8 +85,7 @@ func (p *fingerprint) Run(event *beat.Event) (*beat.Event, error) {
 }
 
 func (p *fingerprint) String() string {
-	//nolint:staticcheck // https://github.com/elastic/beats/issues/35174
-	json, _ := json.Marshal(p.config)
+	json, _ := json.Marshal(&p.config)
 	return procName + "=" + string(json)
 }
 

libbeat/processors/fingerprint/fingerprint_test.go

@@ -18,6 +18,7 @@
 package fingerprint
 
 import (
+	"fmt"
 	"math/rand"
 	"strconv"
 	"testing"
@@ -459,6 +460,18 @@ func TestIgnoreMissing(t *testing.T) {
 	}
 }
 
+func TestProcessorStringer(t *testing.T) {
+	testConfig, err := config.NewConfigFrom(mapstr.M{
+		"fields":   []string{"field1"},
+		"encoding": "hex",
+		"method":   "md5",
+	})
+	assert.NoError(t, err)
+	p, err := New(testConfig)
+	assert.NoError(t, err)
+	assert.Equal(t, `fingerprint={"Method":"md5","Encoding":"hex","Fields":["field1"],"TargetField":"fingerprint","IgnoreMissing":false}`, fmt.Sprint(p))
+}
+
 func BenchmarkHashMethods(b *testing.B) {
 	events := nRandomEvents(100000)
 

libbeat/processors/fingerprint/hash.go

@@ -28,19 +28,29 @@ import (
 	"github.com/cespare/xxhash/v2"
 )
 
+type namedHashMethod struct {
+	Name string
+	Hash hashMethod
+}
 type hashMethod func() hash.Hash
 
-var hashes = map[string]hashMethod{
-	"md5":    md5.New,
-	"sha1":   sha1.New,
-	"sha256": sha256.New,
-	"sha384": sha512.New384,
-	"sha512": sha512.New,
-	"xxhash": newXxHash,
+var hashes = map[string]namedHashMethod{}
+
+func init() {
+	for _, h := range []namedHashMethod{
+		{Name: "md5", Hash: md5.New},
+		{Name: "sha1", Hash: sha1.New},
+		{Name: "sha256", Hash: sha256.New},
+		{Name: "sha384", Hash: sha512.New384},
+		{Name: "sha512", Hash: sha512.New},
+		{Name: "xxhash", Hash: newXxHash},
+	} {
+		hashes[h.Name] = h
+	}
 }
 
 // Unpack creates the hashMethod from the given string
-func (f *hashMethod) Unpack(str string) error {
+func (f *namedHashMethod) Unpack(str string) error {
 	str = strings.ToLower(str)
 
 	m, found := hashes[str]