[exporter/elasticsearch] Fix unset span status serialization (#40345)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Fix a bug where unset span status code was being serialized as "Unset"
instead of being ignored

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue

Fixes #39498

<!--Describe what testing was performed and which tests were added.-->
#### Testing

Unit tests.

Author: ericywl

.chloggen/39498-elasticsearchexporter-fix-span-unset-status.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: elasticsearchexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Fix a bug where unset span status code was being serialized as 'Unset' instead of being ignored"
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [39498]
+
+# (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: [user]

exporter/elasticsearchexporter/exporter_test.go

@@ -2001,7 +2001,7 @@ func TestExporterTraces(t *testing.T) {
 		expected := []itemRequest{
 			{
 				Action:   []byte(`{"create":{"_index":"traces-generic.otel-default"}}`),
-				Document: []byte(`{"@timestamp":"3600000.0","attributes":{"attr.foo":"attr.bar"},"data_stream":{"dataset":"generic.otel","namespace":"default","type":"traces"},"dropped_attributes_count":2,"dropped_events_count":3,"dropped_links_count":4,"duration":3600000000000,"kind":"Unspecified","links":[{"attributes":{"link.attr.foo":"link.attr.bar"},"dropped_attributes_count":11,"span_id":"0100000000000000","trace_id":"01000000000000000000000000000000","trace_state":"bar"}],"name":"name","resource":{"attributes":{"resource.foo":"resource.bar"}},"scope":{},"status":{"code":"Unset"},"trace_state":"foo"}`),
+				Document: []byte(`{"@timestamp":"3600000.0","attributes":{"attr.foo":"attr.bar"},"data_stream":{"dataset":"generic.otel","namespace":"default","type":"traces"},"dropped_attributes_count":2,"dropped_events_count":3,"dropped_links_count":4,"duration":3600000000000,"kind":"Unspecified","links":[{"attributes":{"link.attr.foo":"link.attr.bar"},"dropped_attributes_count":11,"span_id":"0100000000000000","trace_id":"01000000000000000000000000000000","trace_state":"bar"}],"name":"name","resource":{"attributes":{"resource.foo":"resource.bar"}},"scope":{},"status":{},"trace_state":"foo"}`),
 			},
 			{
 				Action:   []byte(`{"create":{"_index":"logs-generic.otel-default"}}`),

exporter/elasticsearchexporter/internal/serializer/otelserializer/traces.go

@@ -72,7 +72,9 @@ func writeStatus(v *json.Visitor, status ptrace.Status) {
 	_ = v.OnKey("status")
 	_ = v.OnObjectStart(-1, structform.AnyType)
 	writeStringFieldSkipDefault(v, "message", status.Message())
-	writeStringFieldSkipDefault(v, "code", status.Code().String())
+	if code := status.Code(); code != ptrace.StatusCodeUnset {
+		writeStringFieldSkipDefault(v, "code", code.String())
+	}
 	_ = v.OnObjectFinished()
 }
 

exporter/elasticsearchexporter/internal/serializer/otelserializer/traces_test.go

@@ -0,0 +1,104 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+package otelserializer
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"go.opentelemetry.io/collector/pdata/pcommon"
+	"go.opentelemetry.io/collector/pdata/ptrace"
+
+	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/elasticsearchexporter/internal/elasticsearch"
+)
+
+func TestSerializeTraces(t *testing.T) {
+	tests := []struct {
+		name           string
+		spanCustomizer func(resource pcommon.Resource, scope pcommon.InstrumentationScope, span ptrace.Span)
+		wantErr        bool
+		expected       any
+	}{
+		{
+			name: "default",
+			spanCustomizer: func(resource pcommon.Resource, scope pcommon.InstrumentationScope, span ptrace.Span) {
+				span.SetStartTimestamp(1721314113467654123)
+				span.SetEndTimestamp(1721314113469654123)
+				span.SetKind(ptrace.SpanKindServer)
+				span.Status().SetCode(ptrace.StatusCodeOk)
+				span.Status().SetMessage("Hello")
+				resource.Attributes().PutInt("foo", 123)
+				scope.Attributes().PutStr("foo", "bar")
+			},
+			wantErr: false,
+			expected: map[string]any{
+				"@timestamp": "1721314113467.654123",
+				"duration":   json.Number("2000000"),
+				"kind":       "Server",
+				"links":      []any{},
+				"resource": map[string]any{
+					"attributes": map[string]any{
+						"foo": json.Number("123"),
+					},
+				},
+				"scope": map[string]any{
+					"attributes": map[string]any{
+						"foo": "bar",
+					},
+				},
+				"status": map[string]any{
+					"code":    "Ok",
+					"message": "Hello",
+				},
+			},
+		},
+		{
+			name: "unset status code",
+			spanCustomizer: func(_ pcommon.Resource, _ pcommon.InstrumentationScope, span ptrace.Span) {
+				span.Status().SetCode(ptrace.StatusCodeUnset)
+			},
+			wantErr: false,
+			expected: map[string]any{
+				"@timestamp": "0.0",
+				"duration":   json.Number("0"),
+				"kind":       "Unspecified",
+				"links":      []any{},
+				"resource":   map[string]any{},
+				"scope":      map[string]any{},
+				"status":     map[string]any{},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			traces := ptrace.NewTraces()
+			resourceSpans := traces.ResourceSpans().AppendEmpty()
+			scopeSpans := resourceSpans.ScopeSpans().AppendEmpty()
+			span := scopeSpans.Spans().AppendEmpty()
+			tt.spanCustomizer(resourceSpans.Resource(), scopeSpans.Scope(), span)
+			traces.MarkReadOnly()
+
+			var buf bytes.Buffer
+			ser, err := New()
+			require.NoError(t, err)
+			err = ser.SerializeSpan(resourceSpans.Resource(), "", scopeSpans.Scope(), "", span, elasticsearch.Index{}, &buf)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("SerializeSpan() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			spanBytes := buf.Bytes()
+			eventAsJSON := string(spanBytes)
+			var result any
+			decoder := json.NewDecoder(bytes.NewBuffer(spanBytes))
+			decoder.UseNumber()
+			if err := decoder.Decode(&result); err != nil {
+				t.Error(err)
+			}
+
+			assert.Equal(t, tt.expected, result, eventAsJSON)
+		})
+	}
+}