[pkg/ottl] Add InsertXML Converter

.chloggen/ottl-add-element-xml.yaml

@@ -0,0 +1,27 @@
+# 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: pkg/ottl
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Add InsertXML Converter
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [35436]
+
+# (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:
+
+# 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: []

pkg/ottl/e2e/e2e_test.go

@@ -420,6 +420,12 @@ func Test_e2e_converters(t *testing.T) {
 				tCtx.GetLogRecord().Attributes().PutDouble("test", 1.5)
 			},
 		},
+		{
+			statement: `set(attributes["test"], InsertXML("<a></a>", "/a", "<b></b>"))`,
+			want: func(tCtx ottllog.TransformContext) {
+				tCtx.GetLogRecord().Attributes().PutStr("test", "<a><b></b></a>")
+			},
+		},
 		{
 			statement: `set(attributes["test"], Int(1.0))`,
 			want: func(tCtx ottllog.TransformContext) {

pkg/ottl/ottlfuncs/README.md

@@ -414,15 +414,16 @@ Available Converters:
 - [Concat](#concat)
 - [ConvertCase](#convertcase)
 - [Day](#day)
+- [Double](#double)
+- [Duration](#duration)
 - [ExtractPatterns](#extractpatterns)
 - [ExtractGrokPatterns](#extractgrokpatterns)
 - [FNV](#fnv)
 - [Format](#format)
 - [Hex](#hex)
 - [Hour](#hour)
 - [Hours](#hours)
-- [Double](#double)
-- [Duration](#duration)
+- [InsertXML](#insertxml)
 - [Int](#int)
 - [IsBool](#isbool)
 - [IsDouble](#isdouble)
@@ -797,6 +798,35 @@ Examples:
 
 - `Hours(Duration("1h"))`
 
+### InsertXML
+
+`InsertXML(target, xpath, value)`
+
+The `InsertXML` Converter returns an edited version of an XML string with child elements added to selected elements.
+
+`target` is a Getter that returns a string. This string should be in XML format and represents the document which will
+be modified. If `target` is not a string, nil, or is not valid xml, `InsertXML` will return an error.
+
+`xpath` is a string that specifies an [XPath](https://www.w3.org/TR/1999/REC-xpath-19991116/) expression that
+selects one or more elements.
+
+`value` is a Getter that returns a string. This string should be in XML format and represents the document which will
+be inserted into `target`. If `value` is not a string, nil, or is not valid xml, `InsertXML` will return an error.
+
+Examples:
+
+Add an element "foo" to the root of the document
+
+- `InsertXML(body, "/", "<foo/>")`
+
+Add an element "bar" to any element called "foo"
+
+- `InsertXML(body, "//foo", "<bar/>")`
+
+Fetch and insert an xml document into another
+
+- `InsertXML(body, "/subdoc", attributes["subdoc"])`
+
 ### Int
 
 `Int(value)`

pkg/ottl/ottlfuncs/func_insert_xml.go

@@ -0,0 +1,75 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/antchfx/xmlquery"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+type InsertXMLArguments[K any] struct {
+	Target      ottl.StringGetter[K]
+	XPath       string
+	SubDocument ottl.StringGetter[K]
+}
+
+func NewInsertXMLFactory[K any]() ottl.Factory[K] {
+	return ottl.NewFactory("InsertXML", &InsertXMLArguments[K]{}, createInsertXMLFunction[K])
+}
+
+func createInsertXMLFunction[K any](_ ottl.FunctionContext, oArgs ottl.Arguments) (ottl.ExprFunc[K], error) {
+	args, ok := oArgs.(*InsertXMLArguments[K])
+
+	if !ok {
+		return nil, fmt.Errorf("InsertXML args must be of type *InsertXMLAguments[K]")
+	}
+
+	if err := validateXPath(args.XPath); err != nil {
+		return nil, err
+	}
+
+	return insertXML(args.Target, args.XPath, args.SubDocument), nil
+}
+
+// insertXML returns a XML formatted string that is a result of inserting another XML document into
+// the content of each selected target element.
+func insertXML[K any](target ottl.StringGetter[K], xPath string, subGetter ottl.StringGetter[K]) ottl.ExprFunc[K] {
+	return func(ctx context.Context, tCtx K) (any, error) {
+		var doc *xmlquery.Node
+		if targetVal, err := target.Get(ctx, tCtx); err != nil {
+			return nil, err
+		} else if doc, err = parseNodesXML(targetVal); err != nil {
+			return nil, err
+		}
+
+		var subDoc *xmlquery.Node
+		if subDocVal, err := subGetter.Get(ctx, tCtx); err != nil {
+			return nil, err
+		} else if subDoc, err = parseNodesXML(subDocVal); err != nil {
+			return nil, err
+		}
+
+		nodes, errs := xmlquery.QueryAll(doc, xPath)
+		for _, n := range nodes {
+			switch n.Type {
+			case xmlquery.ElementNode, xmlquery.DocumentNode:
+				var nextSibling *xmlquery.Node
+				for c := subDoc.FirstChild; c != nil; c = nextSibling {
+					// AddChild updates c.NextSibling but not subDoc.FirstChild
+					// so we need to get the handle to it prior to the update.
+					nextSibling = c.NextSibling
+					xmlquery.AddChild(n, c)
+				}
+			default:
+				errs = errors.Join(errs, fmt.Errorf("InsertXML XPath selected non-element: %q", n.Data))
+			}
+		}
+		return doc.OutputXML(false), errs
+	}
+}

pkg/ottl/ottlfuncs/func_insert_xml_test.go

@@ -0,0 +1,185 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package ottlfuncs // import "github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl/ottlfuncs"
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/pkg/ottl"
+)
+
+func Test_InsertXML(t *testing.T) {
+	tests := []struct {
+		name      string
+		document  string
+		xPath     string
+		subdoc    string
+		want      string
+		expectErr string
+	}{
+		{
+			name:     "add single element",
+			document: `<a></a>`,
+			xPath:    "/a",
+			subdoc:   `<b/>`,
+			want:     `<a><b></b></a>`,
+		},
+		{
+			name:     "add single element to multiple matches",
+			document: `<a></a><a></a>`,
+			xPath:    "/a",
+			subdoc:   `<b/>`,
+			want:     `<a><b></b></a><a><b></b></a>`,
+		},
+		{
+			name:     "add single element at multiple levels",
+			document: `<a></a><z><a></a></z>`,
+			xPath:    "//a",
+			subdoc:   `<b/>`,
+			want:     `<a><b></b></a><z><a><b></b></a></z>`,
+		},
+		{
+			name:     "add multiple elements at root",
+			document: `<a></a>`,
+			xPath:    "/",
+			subdoc:   `<b/><c/>`,
+			want:     `<a></a><b></b><c></c>`,
+		},
+		{
+			name:     "add multiple elements to other element",
+			document: `<a></a>`,
+			xPath:    "/a",
+			subdoc:   `<b/><c/>`,
+			want:     `<a><b></b><c></c></a>`,
+		},
+		{
+			name:     "add multiple elements to multiple elements",
+			document: `<a></a><a></a>`,
+			xPath:    "/a",
+			subdoc:   `<b/><c/>`,
+			want:     `<a><b></b><c></c></a><a><b></b><c></c></a>`,
+		},
+		{
+			name:     "add multiple elements at multiple levels",
+			document: `<a></a><z><a></a></z>`,
+			xPath:    "//a",
+			subdoc:   `<b/><c/>`,
+			want:     `<a><b></b><c></c></a><z><a><b></b><c></c></a></z>`,
+		},
+		{
+			name:     "add rich doc",
+			document: `<a></a>`,
+			xPath:    "/a",
+			subdoc:   `<x foo="bar"><b>text</b><c><d><e>1</e><e><![CDATA[two]]></e></d></c></x>`,
+			want:     `<a><x foo="bar"><b>text</b><c><d><e>1</e><e><![CDATA[two]]></e></d></c></x></a>`,
+		},
+		{
+			name:     "add root element to empty document",
+			document: ``,
+			xPath:    "/",
+			subdoc:   `<a/>`,
+			want:     `<a></a>`,
+		},
+		{
+			name:     "add root element to non-empty document",
+			document: `<a></a>`,
+			xPath:    "/",
+			subdoc:   `<a/>`,
+			want:     `<a></a><a></a>`,
+		},
+		{
+			name:      "err on attribute",
+			document:  `<a foo="bar"></a>`,
+			xPath:     "/a/@foo",
+			subdoc:    "<b/>",
+			want:      `<a foo="bar"></a>`,
+			expectErr: `InsertXML XPath selected non-element: "foo"`,
+		},
+		{
+			name:      "err on text content",
+			document:  `<a>foo</a>`,
+			xPath:     "/a/text()",
+			subdoc:    "<b/>",
+			want:      `<a>foo</a>`,
+			expectErr: `InsertXML XPath selected non-element: "foo"`,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f := NewInsertXMLFactory[any]()
+			exprFunc, err := f.CreateFunction(
+				ottl.FunctionContext{},
+				&InsertXMLArguments[any]{
+					Target: ottl.StandardStringGetter[any]{
+						Getter: func(_ context.Context, _ any) (any, error) {
+							return tt.document, nil
+						},
+					},
+					XPath: tt.xPath,
+					SubDocument: ottl.StandardStringGetter[any]{
+						Getter: func(_ context.Context, _ any) (any, error) {
+							return tt.subdoc, nil
+						},
+					},
+				})
+			assert.NoError(t, err)
+
+			result, err := exprFunc(context.Background(), nil)
+			if tt.expectErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tt.expectErr)
+			}
+			assert.Equal(t, tt.want, result)
+		})
+	}
+}
+
+func TestCreateInsertXMLFunc(t *testing.T) {
+	factory := NewInsertXMLFactory[any]()
+	fCtx := ottl.FunctionContext{}
+
+	// Invalid arg type
+	exprFunc, err := factory.CreateFunction(fCtx, nil)
+	assert.Error(t, err)
+	assert.Nil(t, exprFunc)
+
+	// Invalid XPath should error on function creation
+	exprFunc, err = factory.CreateFunction(
+		fCtx, &InsertXMLArguments[any]{
+			XPath: "!",
+		})
+	assert.Error(t, err)
+	assert.Nil(t, exprFunc)
+
+	// Invalid XML target should error on function execution
+	exprFunc, err = factory.CreateFunction(
+		fCtx, &InsertXMLArguments[any]{
+			Target: invalidXMLGetter(),
+			XPath:  "/",
+		})
+	assert.NoError(t, err)
+	assert.NotNil(t, exprFunc)
+	_, err = exprFunc(context.Background(), nil)
+	assert.Error(t, err)
+
+	// Invalid XML subdoc should error on function execution
+	exprFunc, err = factory.CreateFunction(
+		fCtx, &InsertXMLArguments[any]{
+			Target: ottl.StandardStringGetter[any]{
+				Getter: func(_ context.Context, _ any) (any, error) {
+					return "<a/>", nil
+				},
+			},
+			XPath:       "/",
+			SubDocument: invalidXMLGetter(),
+		})
+	assert.NoError(t, err)
+	assert.NotNil(t, exprFunc)
+	_, err = exprFunc(context.Background(), nil)
+	assert.Error(t, err)
+}

pkg/ottl/ottlfuncs/func_remove_xml.go

@@ -82,7 +82,7 @@ func parseNodesXML(targetVal string) (*xmlquery.Node, error) {
 	if err != nil {
 		return nil, fmt.Errorf("parse xml: %w", err)
 	}
-	if !preserveDeclearation {
+	if !preserveDeclearation && top.FirstChild != nil {
 		xmlquery.RemoveFromTree(top.FirstChild)
 	}
 	return top, nil

pkg/ottl/ottlfuncs/functions.go

@@ -48,6 +48,7 @@ func converters[K any]() []ottl.Factory[K] {
 		NewFnvFactory[K](),
 		NewHourFactory[K](),
 		NewHoursFactory[K](),
+		NewInsertXMLFactory[K](),
 		NewIntFactory[K](),
 		NewIsBoolFactory[K](),
 		NewIsDoubleFactory[K](),