[processor/transform] Add support for flat configuration style (#37444)

Co-authored-by: Evan Bradley <[email protected]>

.chloggen/add-config-flat-statements-support.yaml

@@ -0,0 +1,30 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: processor/transformprocessor
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add support for flat configuration style.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [29017]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  The flat configuration style allows users to configure statements by providing a list of statements instead of a
+  structured configuration map. The statement's context is expressed by adding the context's name prefix to path names,
+  which are used to infer and to select the appropriate context for the statement.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

processor/transformprocessor/config.go

@@ -5,8 +5,11 @@ package transformprocessor // import "github.com/open-telemetry/opentelemetry-co
 
 import (
 	"errors"
+	"fmt"
+	"reflect"
 
 	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/confmap"
 	"go.opentelemetry.io/collector/featuregate"
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
@@ -44,6 +47,86 @@ type Config struct {
 	logger      *zap.Logger
 }
 
+// Unmarshal is used internally by mapstructure to parse the transformprocessor configuration (Config),
+// adding support to structured and flat configuration styles.
+// When the flat configuration style is used, each statement becomes a new common.ContextStatements
+// object, with empty [common.ContextStatements.Context] value.
+// On the other hand, structured configurations are parsed following the mapstructure Config format.
+// Mixed configuration styles are also supported.
+//
+// Example of flat configuration:
+//
+//	log_statements:
+//	  - set(attributes["service.new_name"], attributes["service.name"])
+//	  - delete_key(attributes, "service.name")
+//
+// Example of structured configuration:
+//
+//	log_statements:
+//	  - context: "span"
+//	    statements:
+//	      - set(attributes["service.new_name"], attributes["service.name"])
+//	      - delete_key(attributes, "service.name")
+func (c *Config) Unmarshal(conf *confmap.Conf) error {
+	if conf == nil {
+		return nil
+	}
+
+	contextStatementsFields := map[string]*[]common.ContextStatements{
+		"trace_statements":  &c.TraceStatements,
+		"metric_statements": &c.MetricStatements,
+		"log_statements":    &c.LogStatements,
+	}
+
+	flatContextStatements := map[string][]int{}
+	contextStatementsPatch := map[string]any{}
+	for fieldName := range contextStatementsFields {
+		if !conf.IsSet(fieldName) {
+			continue
+		}
+		rawVal := conf.Get(fieldName)
+		values, ok := rawVal.([]any)
+		if !ok {
+			return fmt.Errorf("invalid %s type, expected: array, got: %t", fieldName, rawVal)
+		}
+		if len(values) == 0 {
+			continue
+		}
+
+		stmts := make([]any, 0, len(values))
+		for i, value := range values {
+			// Array of strings means it's a flat configuration style
+			if reflect.TypeOf(value).Kind() == reflect.String {
+				stmts = append(stmts, map[string]any{"statements": []any{value}})
+				flatContextStatements[fieldName] = append(flatContextStatements[fieldName], i)
+			} else {
+				stmts = append(stmts, value)
+			}
+		}
+		contextStatementsPatch[fieldName] = stmts
+	}
+
+	if len(contextStatementsPatch) > 0 {
+		err := conf.Merge(confmap.NewFromStringMap(contextStatementsPatch))
+		if err != nil {
+			return err
+		}
+	}
+
+	err := conf.Unmarshal(c)
+	if err != nil {
+		return err
+	}
+
+	for fieldName, indexes := range flatContextStatements {
+		for _, i := range indexes {
+			(*contextStatementsFields[fieldName])[i].SharedCache = true
+		}
+	}
+
+	return err
+}
+
 var _ component.Config = (*Config)(nil)
 
 func (c *Config) Validate() error {

processor/transformprocessor/config_test.go

@@ -205,6 +205,108 @@ func TestLoadConfig(t *testing.T) {
 				},
 			},
 		},
+		{
+			id: component.NewIDWithName(metadata.Type, "flat_configuration"),
+			expected: &Config{
+				ErrorMode: ottl.PropagateError,
+				TraceStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(span.name, "bear") where span.attributes["http.path"] == "/animal"`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(resource.attributes["name"], "bear")`},
+					},
+				},
+				MetricStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(metric.name, "bear") where resource.attributes["http.path"] == "/animal"`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(resource.attributes["name"], "bear")`},
+					},
+				},
+				LogStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(log.body, "bear") where log.attributes["http.path"] == "/animal"`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(resource.attributes["name"], "bear")`},
+					},
+				},
+			},
+		},
+		{
+			id: component.NewIDWithName(metadata.Type, "mixed_configuration_styles"),
+			expected: &Config{
+				ErrorMode: ottl.PropagateError,
+				TraceStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(span.name, "bear") where span.attributes["http.path"] == "/animal"`},
+					},
+					{
+						Context: "span",
+						Statements: []string{
+							`set(attributes["name"], "bear")`,
+							`keep_keys(attributes, ["http.method", "http.path"])`,
+						},
+					},
+					{
+						Statements: []string{`set(span.attributes["name"], "lion")`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(span.name, "lion") where span.attributes["http.path"] == "/animal"`},
+					},
+				},
+				MetricStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(metric.name, "bear") where resource.attributes["http.path"] == "/animal"`},
+					},
+					{
+						Context: "resource",
+						Statements: []string{
+							`set(attributes["name"], "bear")`,
+							`keep_keys(attributes, ["http.method", "http.path"])`,
+						},
+					},
+					{
+						Statements: []string{`set(metric.name, "lion")`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(metric.name, "lion") where resource.attributes["http.path"] == "/animal"`},
+					},
+				},
+				LogStatements: []common.ContextStatements{
+					{
+						SharedCache: true,
+						Statements:  []string{`set(log.body, "bear") where log.attributes["http.path"] == "/animal"`},
+					},
+					{
+						Context: "resource",
+						Statements: []string{
+							`set(attributes["name"], "bear")`,
+							`keep_keys(attributes, ["http.method", "http.path"])`,
+						},
+					},
+					{
+						Statements: []string{`set(log.attributes["name"], "lion")`},
+					},
+					{
+						SharedCache: true,
+						Statements:  []string{`set(log.body, "lion") where log.attributes["http.path"] == "/animal"`},
+					},
+				},
+			},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.id.Name(), func(t *testing.T) {

processor/transformprocessor/internal/common/cache.go

@@ -0,0 +1,20 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package common // import "github.com/open-telemetry/opentelemetry-collector-contrib/processor/transformprocessor/internal/common"
+
+import (
+	"go.opentelemetry.io/collector/pdata/pcommon"
+)
+
+// LoadContextCache retrieves or creates a context cache map for the given context ID.
+// If the cache is not found, a new map is created and stored in the contextCache map.
+func LoadContextCache(contextCache map[ContextID]*pcommon.Map, context ContextID) *pcommon.Map {
+	v, ok := contextCache[context]
+	if ok {
+		return v
+	}
+	m := pcommon.NewMap()
+	contextCache[context] = &m
+	return &m
+}

processor/transformprocessor/internal/common/config.go

@@ -39,6 +39,11 @@ type ContextStatements struct {
 	Context    ContextID `mapstructure:"context"`
 	Conditions []string  `mapstructure:"conditions"`
 	Statements []string  `mapstructure:"statements"`
+
+	// `SharedCache` is an experimental feature that may change or be removed in the future.
+	// When enabled, it allows the statements cache to be shared across all other groups that share the cache.
+	// This feature is not configurable via `mapstructure` and cannot be set in configuration files.
+	SharedCache bool `mapstructure:"-"`
 }
 
 func (c ContextStatements) GetStatements() []string {

processor/transformprocessor/internal/common/logs.go

@@ -75,6 +75,7 @@ func WithLogErrorMode(errorMode ottl.ErrorMode) LogParserCollectionOption {
 func NewLogParserCollection(settings component.TelemetrySettings, options ...LogParserCollectionOption) (*LogParserCollection, error) {
 	pcOptions := []ottl.ParserCollectionOption[LogsConsumer]{
 		withCommonContextParsers[LogsConsumer](),
+		ottl.EnableParserCollectionModifiedStatementLogging[LogsConsumer](true),
 	}
 
 	for _, option := range options {

processor/transformprocessor/internal/common/metrics.go

@@ -195,6 +195,7 @@ func WithMetricErrorMode(errorMode ottl.ErrorMode) MetricParserCollectionOption
 func NewMetricParserCollection(settings component.TelemetrySettings, options ...MetricParserCollectionOption) (*MetricParserCollection, error) {
 	pcOptions := []ottl.ParserCollectionOption[MetricsConsumer]{
 		withCommonContextParsers[MetricsConsumer](),
+		ottl.EnableParserCollectionModifiedStatementLogging[MetricsConsumer](true),
 	}
 
 	for _, option := range options {

processor/transformprocessor/internal/common/traces.go

@@ -123,6 +123,7 @@ func WithTraceErrorMode(errorMode ottl.ErrorMode) TraceParserCollectionOption {
 func NewTraceParserCollection(settings component.TelemetrySettings, options ...TraceParserCollectionOption) (*TraceParserCollection, error) {
 	pcOptions := []ottl.ParserCollectionOption[TracesConsumer]{
 		withCommonContextParsers[TracesConsumer](),
+		ottl.EnableParserCollectionModifiedStatementLogging[TracesConsumer](true),
 	}
 
 	for _, option := range options {

processor/transformprocessor/internal/logs/processor.go

@@ -7,6 +7,7 @@ import (
 	"context"
 
 	"go.opentelemetry.io/collector/component"
+	"go.opentelemetry.io/collector/pdata/pcommon"
 	"go.opentelemetry.io/collector/pdata/plog"
 	"go.uber.org/multierr"
 	"go.uber.org/zap"
@@ -16,8 +17,13 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/processor/transformprocessor/internal/common"
 )
 
+type parsedContextStatements struct {
+	common.LogsConsumer
+	sharedCache bool
+}
+
 type Processor struct {
-	contexts []common.LogsConsumer
+	contexts []parsedContextStatements
 	logger   *zap.Logger
 	flatMode bool
 }
@@ -28,14 +34,14 @@ func NewProcessor(contextStatements []common.ContextStatements, errorMode ottl.E
 		return nil, err
 	}
 
-	contexts := make([]common.LogsConsumer, len(contextStatements))
+	contexts := make([]parsedContextStatements, len(contextStatements))
 	var errors error
 	for i, cs := range contextStatements {
 		context, err := pc.ParseContextStatements(cs)
 		if err != nil {
 			errors = multierr.Append(errors, err)
 		}
-		contexts[i] = context
+		contexts[i] = parsedContextStatements{context, cs.SharedCache}
 	}
 
 	if errors != nil {
@@ -54,8 +60,14 @@ func (p *Processor) ProcessLogs(ctx context.Context, ld plog.Logs) (plog.Logs, e
 		pdatautil.FlattenLogs(ld.ResourceLogs())
 		defer pdatautil.GroupByResourceLogs(ld.ResourceLogs())
 	}
+
+	sharedContextCache := make(map[common.ContextID]*pcommon.Map, len(p.contexts))
 	for _, c := range p.contexts {
-		err := c.ConsumeLogs(ctx, ld, nil)
+		var cache *pcommon.Map
+		if c.sharedCache {
+			cache = common.LoadContextCache(sharedContextCache, c.Context())
+		}
+		err := c.ConsumeLogs(ctx, ld, cache)
 		if err != nil {
 			p.logger.Error("failed processing logs", zap.Error(err))
 			return ld, err