[translator/loki] Fixes a panic that occurred during the promotion of…

… nested attributes containing dots to labels (#25142)

When the value for loki hint attribute contains dots (more than 1 dot)
and attributes are nested so some level contains dotted attribute name
(for example `{"log": {"file.name": "foo"}}`), the getNestedAttribute
function throws a panic

Co-authored-by: Tyler Helmuth <[email protected]>

.chloggen/fix-loki-translator-nested-attributes.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: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: lokitranslator, lokiexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fixes a panic that occurred during the promotion of nested attributes containing dots to labels
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [25125]
+
+# (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/translator/loki/convert.go

@@ -32,6 +32,8 @@ const (
 	levelLabel    string = "level"
 )
 
+const attrSeparator = "."
+
 func convertAttributesAndMerge(logAttrs pcommon.Map, resAttrs pcommon.Map, defaultLabelsEnabled map[string]bool) model.LabelSet {
 	out := getDefaultLabels(resAttrs, defaultLabelsEnabled)
 
@@ -97,33 +99,34 @@ func convertAttributesToLabels(attributes pcommon.Map, attrsToSelect pcommon.Val
 	for _, attr := range attrs {
 		attr = strings.TrimSpace(attr)
 
-		av, ok := attributes.Get(attr)
-		if !ok {
-			// couldn't find the attribute under the given name directly
-			// perhaps it's a nested attribute?
-			av, ok = getNestedAttribute(attr, attributes) // shadows the OK from above on purpose
-		}
-
-		if ok {
+		if av, ok := getAttribute(attr, attributes); ok {
 			out[model.LabelName(attr)] = model.LabelValue(av.AsString())
 		}
 	}
 
 	return out
 }
 
-func getNestedAttribute(attr string, attributes pcommon.Map) (pcommon.Value, bool) {
-	left, right, _ := strings.Cut(attr, ".")
-	av, ok := attributes.Get(left)
-	if !ok {
-		return pcommon.Value{}, false
-	}
-
-	if len(right) == 0 {
+func getAttribute(attr string, attributes pcommon.Map) (pcommon.Value, bool) {
+	if av, ok := attributes.Get(attr); ok {
 		return av, ok
 	}
 
-	return getNestedAttribute(right, av.Map())
+	// couldn't find the attribute under the given name directly
+	// perhaps it's a nested attribute?
+	segments := strings.Split(attr, attrSeparator)
+	segmentsNumber := len(segments)
+	for i := 0; i < segmentsNumber-1; i++ {
+		left := strings.Join(segments[:segmentsNumber-i-1], attrSeparator)
+		right := strings.Join(segments[segmentsNumber-i-1:], attrSeparator)
+
+		if av, ok := getAttribute(left, attributes); ok {
+			if av.Type() == pcommon.ValueTypeMap {
+				return getAttribute(right, av.Map())
+			}
+		}
+	}
+	return pcommon.Value{}, false
 }
 
 func parseAttributeNames(attrsToSelect pcommon.Value) []string {

pkg/translator/loki/convert_test.go

@@ -290,22 +290,99 @@ func TestRemoveAttributes(t *testing.T) {
 	}
 }
 
-func TestGetNestedAttribute(t *testing.T) {
-	// prepare
-	attrs := pcommon.NewMap()
-	err := attrs.FromRaw(map[string]interface{}{
-		"host": map[string]interface{}{
-			"name": "guarana",
+func TestGetAttribute(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		attr     string
+		attrs    map[string]interface{}
+		expected pcommon.Value
+		ok       bool
+	}{
+		{
+			desc: "attributes don't contain dotted names",
+			attr: "host.name",
+			attrs: map[string]interface{}{
+				"host": map[string]interface{}{
+					"name": "guarana",
+				},
+			},
+			expected: pcommon.NewValueStr("guarana"),
+			ok:       true,
 		},
-	})
-	require.NoError(t, err)
+		{
+			desc: "attributes contain dotted name on the nested level",
+			attr: "log.file.name",
+			attrs: map[string]interface{}{
+				"log": map[string]interface{}{
+					"file.name": "foo",
+				},
+			},
+			expected: pcommon.NewValueStr("foo"),
+			ok:       true,
+		},
+		{
+			desc: "attributes contain dotted name on the upper level",
+			attr: "log.file.name",
+			attrs: map[string]interface{}{
+				"log.file": map[string]interface{}{
+					"name": "foo",
+				},
+			},
+			expected: pcommon.NewValueStr("foo"),
+			ok:       true,
+		},
+		{
+			desc: "attributes contain dotted attribute",
+			attr: "log.file.name",
+			attrs: map[string]interface{}{
+				"log.file.name": "foo",
+			},
+			expected: pcommon.NewValueStr("foo"),
+			ok:       true,
+		},
+		{
+			desc: "dotted name that doesn't match attr",
+			attr: "log.file.name",
+			attrs: map[string]interface{}{
+				"log.file": "foo",
+			},
+			expected: pcommon.Value{},
+			ok:       false,
+		},
+		{
+			desc: "should get the longest match",
+			attr: "log.file.name",
+			attrs: map[string]interface{}{
+				"log.file.name": "foo",
+				"log": map[string]interface{}{
+					"file": map[string]interface{}{
+						"name": "bar",
+					},
+				},
+				"log.file": map[string]interface{}{
+					"name": "baz",
+				},
+			},
+			expected: pcommon.NewValueStr("foo"),
+			ok:       true,
+		},
+	}
+
+	for _, tC := range testCases {
+		t.Run(tC.desc, func(t *testing.T) {
+			// prepare
+			attrs := pcommon.NewMap()
+			err := attrs.FromRaw(tC.attrs)
+			require.NoError(t, err)
 
-	// test
-	attr, ok := getNestedAttribute("host.name", attrs)
+			// test
+			attr, ok := getAttribute(tC.attr, attrs)
 
-	// verify
-	assert.Equal(t, "guarana", attr.AsString())
-	assert.True(t, ok)
+			// verify
+			assert.Equal(t, tC.expected, attr)
+			assert.Equal(t, tC.ok, ok)
+		})
+	}
 }
 
 func TestConvertLogToLogRawEntry(t *testing.T) {