feat(processors.parser): Add base64 decode for fields

plugins/processors/parser/README.md

@@ -20,6 +20,11 @@ See the [CONFIGURATION.md][CONFIGURATION.md] for more details.
   ## The name of the fields whose value will be parsed.
   parse_fields = ["message"]
 
+  ## Fields to base64 decode.
+  ## These fields do not need to be specified in parse_fields.
+  ## Fields specified here will have base64 decode applied to them.
+  # parse_fields_base64 = []
+
   ## The name of the tags whose value will be parsed.
   # parse_tags = []
 

plugins/processors/parser/parser.go

@@ -4,8 +4,10 @@ package parser
 import (
 	"bytes"
 	_ "embed"
+	"encoding/base64"
 	gobin "encoding/binary"
 	"fmt"
+	"slices"
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal"
@@ -19,6 +21,7 @@ type Parser struct {
 	DropOriginal bool            `toml:"drop_original"`
 	Merge        string          `toml:"merge"`
 	ParseFields  []string        `toml:"parse_fields"`
+	Base64Fields []string        `toml:"parse_fields_base64"`
 	ParseTags    []string        `toml:"parse_tags"`
 	Log          telegraf.Logger `toml:"-"`
 	parser       telegraf.Parser
@@ -53,39 +56,57 @@ func (p *Parser) Apply(metrics ...telegraf.Metric) []telegraf.Metric {
 		}
 
 		// parse fields
-		for _, key := range p.ParseFields {
-			for _, field := range metric.FieldList() {
-				if field.Key != key {
-					continue
-				}
-				value, err := p.toBytes(field.Value)
-				if err != nil {
-					p.Log.Errorf("could not convert field %s: %v; skipping", key, err)
-					continue
-				}
-				fromFieldMetric, err := p.parser.Parse(value)
+		for _, field := range metric.FieldList() {
+			plain := slices.Contains(p.ParseFields, field.Key)
+			b64 := slices.Contains(p.Base64Fields, field.Key)
+
+			if !plain && !b64 {
+				continue
+			}
+
+			if plain && b64 {
+				p.Log.Errorf("field %s is listed in both parse fields and base64 fields; skipping", field.Key)
+				continue
+			}
+
+			value, err := p.toBytes(field.Value)
+			if err != nil {
+				p.Log.Errorf("could not convert field %s: %v; skipping", field.Key, err)
+				continue
+			}
+
+			if b64 {
+				decoded := make([]byte, base64.StdEncoding.DecodedLen(len(value)))
+				n, err := base64.StdEncoding.Decode(decoded, value)
 				if err != nil {
-					p.Log.Errorf("could not parse field %s: %v", key, err)
+					p.Log.Errorf("could not decode base64 field %s: %v; skipping", field.Key, err)
 					continue
 				}
+				value = decoded[:n]
+			}
 
-				for _, m := range fromFieldMetric {
-					// The parser get the parent plugin's name as
-					// default measurement name. Thus, in case the
-					// parsed metric does not provide a name itself,
-					// the parser  will return 'parser' as we are in
-					// processors.parser. In those cases we want to
-					// keep the original metric name.
-					if m.Name() == "" || m.Name() == "parser" {
-						m.SetName(metric.Name())
-					}
-				}
+			fromFieldMetric, err := p.parser.Parse(value)
+			if err != nil {
+				p.Log.Errorf("could not parse field %s: %v", field.Key, err)
+				continue
+			}
 
-				// multiple parsed fields shouldn't create multiple
-				// metrics so we'll merge tags/fields down into one
-				// prior to returning.
-				newMetrics = append(newMetrics, fromFieldMetric...)
+			for _, m := range fromFieldMetric {
+				// The parser get the parent plugin's name as
+				// default measurement name. Thus, in case the
+				// parsed metric does not provide a name itself,
+				// the parser  will return 'parser' as we are in
+				// processors.parser. In those cases we want to
+				// keep the original metric name.
+				if m.Name() == "" || m.Name() == "parser" {
+					m.SetName(metric.Name())
+				}
 			}
+
+			// multiple parsed fields shouldn't create multiple
+			// metrics so we'll merge tags/fields down into one
+			// prior to returning.
+			newMetrics = append(newMetrics, fromFieldMetric...)
 		}
 
 		// parse tags

plugins/processors/parser/parser_test.go

@@ -24,6 +24,7 @@ func TestApply(t *testing.T) {
 		name         string
 		parseFields  []string
 		parseTags    []string
+		parseBase64  []string
 		parser       telegraf.Parser
 		dropOriginal bool
 		merge        string
@@ -708,6 +709,103 @@ func TestApply(t *testing.T) {
 					time.Unix(1593287020, 0)),
 			},
 		},
+		{
+			name:         "test base 64 field single",
+			parseBase64:  []string{"sample"},
+			dropOriginal: true,
+			parser: &json.Parser{
+				TagKeys: []string{
+					"text",
+				},
+			},
+			input: metric.New(
+				"singleField",
+				map[string]string{
+					"some": "tag",
+				},
+				map[string]interface{}{
+					"sample": `eyJ0ZXh0IjogInRlc3QgYmFzZTY0In0=`,
+				},
+				time.Unix(0, 0)),
+			expected: []telegraf.Metric{
+				metric.New(
+					"singleField",
+					map[string]string{
+						"text": "test base64",
+					},
+					map[string]interface{}{},
+					time.Unix(0, 0)),
+			},
+		},
+		{
+			name:         "parse two base64 fields",
+			parseBase64:  []string{"field_1", "field_2"},
+			dropOriginal: true,
+			parser: &json.Parser{
+				TagKeys: []string{"lvl", "msg", "err", "fatal"},
+			},
+			input: metric.New(
+				"bigMeasure",
+				map[string]string{},
+				map[string]interface{}{
+					"field_1": `eyJsdmwiOiJpbmZvIiwibXNnIjoiaHR0cCByZXF1ZXN0In0=`,
+					"field_2": `eyJlcnIiOiJmYXRhbCIsImZhdGFsIjoic2VjdXJpdHkgdGhyZWF0In0=`,
+				},
+				time.Unix(0, 0)),
+			expected: []telegraf.Metric{
+				metric.New(
+					"bigMeasure",
+					map[string]string{
+						"lvl": "info",
+						"msg": "http request",
+					},
+					map[string]interface{}{},
+					time.Unix(0, 0)),
+				metric.New(
+					"bigMeasure",
+					map[string]string{
+						"err":   "fatal",
+						"fatal": "security threat",
+					},
+					map[string]interface{}{},
+					time.Unix(0, 0)),
+			},
+		},
+		{
+			name:         "parse two fields, one base64",
+			parseFields:  []string{"field_2"},
+			parseBase64:  []string{"field_1"},
+			dropOriginal: true,
+			parser: &json.Parser{
+				TagKeys: []string{"lvl", "msg", "err", "fatal"},
+			},
+			input: metric.New(
+				"bigMeasure",
+				map[string]string{},
+				map[string]interface{}{
+					"field_1": `eyJsdmwiOiJpbmZvIiwibXNnIjoiaHR0cCByZXF1ZXN0In0=`,
+					"field_2": `{"err":"fatal","fatal":"security threat"}`,
+				},
+				time.Unix(0, 0)),
+			expected: []telegraf.Metric{
+				metric.New(
+					"bigMeasure",
+					map[string]string{
+						"lvl": "info",
+						"msg": "http request",
+					},
+					map[string]interface{}{},
+					time.Unix(0, 0)),
+				metric.New(
+					"bigMeasure",
+					map[string]string{
+						"err":   "fatal",
+						"fatal": "security threat",
+					},
+					map[string]interface{}{},
+					time.Unix(0, 0)),
+			},
+		},
 	}
 
 	for _, tt := range tests {
@@ -718,6 +816,7 @@ func TestApply(t *testing.T) {
 			plugin := Parser{
 				ParseFields:  tt.parseFields,
 				ParseTags:    tt.parseTags,
+				Base64Fields: tt.parseBase64,
 				DropOriginal: tt.dropOriginal,
 				Merge:        tt.merge,
 				Log:          testutil.Logger{Name: "processor.parser"},
@@ -812,6 +911,37 @@ func TestBadApply(t *testing.T) {
 	}
 }
 
+func TestBase64FieldValidation(t *testing.T) {
+	testMetric := metric.New(
+		"test",
+		map[string]string{},
+		map[string]interface{}{
+			"b": `eyJsdmwiOiJpbmZvIiwibXNnIjoiaHR0cCByZXF1ZXN0In0=`,
+		},
+		time.Unix(0, 0))
+
+	testLogger := &testutil.CaptureLogger{}
+	plugin := &Parser{
+		ParseFields:  []string{"a"},
+		Base64Fields: []string{"b"},
+		Log:          testLogger,
+	}
+	plugin.SetParser(&json.Parser{})
+	require.NoError(t, plugin.Init())
+	plugin.Apply(testMetric)
+	require.Empty(t, testLogger.Errors())
+
+	plugin = &Parser{
+		ParseFields:  []string{"b"},
+		Base64Fields: []string{"b"},
+		Log:          testLogger,
+	}
+	plugin.SetParser(&json.Parser{})
+	require.NoError(t, plugin.Init())
+	plugin.Apply(testMetric)
+	require.NotEmpty(t, testLogger.Errors())
+}
+
 func TestTracking(t *testing.T) {
 	var testCases = []struct {
 		name       string

plugins/processors/parser/sample.conf

@@ -3,6 +3,11 @@
   ## The name of the fields whose value will be parsed.
   parse_fields = ["message"]
 
+  ## Fields to base64 decode.
+  ## These fields do not need to be specified in parse_fields.
+  ## Fields specified here will have base64 decode applied to them.
+  # parse_fields_base64 = []
+
   ## The name of the tags whose value will be parsed.
   # parse_tags = []