[pkg/ottl] add duration converter function

.chloggen/feat_duration-func.yaml

@@ -9,7 +9,7 @@ change_type: 'enhancement'
 component: 'pkg/ottl'
 
 # A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
-note: "Add new `Duration` converter to convert string to a Golang duration"
+note: "Add new `Duration` converter to convert string to a Golang time.duration"
 
 # Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
 issues: [22015]

pkg/ottl/ottlfuncs/README.md

@@ -278,6 +278,7 @@ Available Converters:
 - [Concat](#concat)
 - [ConvertCase](#convertcase)
 - [FNV](#fnv)
+- [Duration](#duration)
 - [Int](#int)
 - [IsMap](#ismap)
 - [IsMatch](#ismatch)
@@ -288,6 +289,7 @@ Available Converters:
 - [SHA256](#sha256)
 - [SpanID](#spanid)
 - [Split](#split)
+- [Time](#time)
 - [TraceID](#traceid)
 - [Substring](#substring)
 - [UUID](#UUID)
@@ -335,6 +337,20 @@ Examples:
 
 - `ConvertCase(metric.name, "snake")`
 
+### Duration
+
+The `Duration` Converter taking a string representation of a duration and converts it to a Golang `time.duration`.
+
+`duration` is a string.
+
+If either `duration` is nil or is in a format that cannot be converted to Golang `time.duration`, an error is returned.
+
+Examples:
+
+- `Duration("3s")`
+- `Duration("333ms")`
+- `Duration("1000000h")`
+
 ### FNV
 
 `FNV(value)`
@@ -569,6 +585,18 @@ Examples:
 
 - ```Split("A|B|C", "|")```
 
+### Time
+
+The `Time` Converter taking a string representation of a duration and converts it to a Golang `time.duration`.
+
+`time` is a string. `format` is a string.
+
+If either `time` or `format` are nil, an error is returned. The parser used is the parser at [internal/coreinternal/parser](github.com/open-telemetry/opentelemetry-collector-contrib/internal/coreinternal/timeutils). If the time and format do not follow the parsing rules used by this parser, an error is returned.
+
+Examples:
+
+- `Time("02/04/2023", "%m/%d/%Y")`
+
 ### TraceID
 
 `TraceID(bytes)`

pkg/ottl/ottlfuncs/func_duration.go

@@ -34,9 +34,6 @@ func Duration[K any](duration ottl.StringGetter[K]) (ottl.ExprFunc[K], error) {
 		if err != nil {
 			return nil, err
 		}
-		// if d == "" {
-		// 	return nil, fmt.Errorf("duration cannot be nil")
-		// }
 		dur, err := time.ParseDuration(d)
 		if err != nil {
 			return nil, err

pkg/ottl/ottlfuncs/func_duration_test.go

@@ -180,15 +180,6 @@ func Test_DurationError(t *testing.T) {
 			},
 			expectedError: "invalid duration",
 		},
-		{
-			name: "empty duration",
-			duration: &ottl.StandardStringGetter[interface{}]{
-				Getter: func(ctx context.Context, tCtx interface{}) (interface{}, error) {
-					return "unknown unit", nil
-				},
-			},
-			expectedError: "invalid duration",
-		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {