[exporter/clickhouse] Fix incorrect ServiceName set for Logs Records (#36350)

#### Description
Fixing a bug in `clickhouseexporter` when ServiceName field in
ClickHouse for `otel_logs` table is set from previous Log Record, when
current LogRecord doesn't have `service.name` set

#### Link to tracking issue
Fixes #36349

#### Testing
Respective unit test is added to code

---------

Co-authored-by: Christos Markou <[email protected]>
Co-authored-by: Alex Boten <[email protected]>

Author: 3 people

.chloggen/fix_clickhouse-exporter-log-service-name.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: clickhouseexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix incorrect Resource Attribute `service.name` translation to ClickHouse ServiceName field for Logs Records
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [36349]
+
+# (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: []

exporter/clickhouseexporter/exporter_logs.go

@@ -71,13 +71,13 @@ func (e *logsExporter) pushLogsData(ctx context.Context, ld plog.Logs) error {
 		defer func() {
 			_ = statement.Close()
 		}()
-		var serviceName string
 
 		for i := 0; i < ld.ResourceLogs().Len(); i++ {
 			logs := ld.ResourceLogs().At(i)
 			res := logs.Resource()
 			resURL := logs.SchemaUrl()
 			resAttr := attributesToMap(res.Attributes())
+			var serviceName string
 			if v, ok := res.Attributes().Get(conventions.AttributeServiceName); ok {
 				serviceName = v.Str()
 			}

exporter/clickhouseexporter/exporter_logs_test.go

@@ -128,6 +128,22 @@ func TestExporter_pushLogsData(t *testing.T) {
 		exporter := newTestLogsExporter(t, defaultEndpoint)
 		mustPushLogsData(t, exporter, simpleLogsWithNoTimestamp(1))
 	})
+	t.Run("test with 2 log records with different service.name", func(t *testing.T) {
+		initClickhouseTestServer(t, func(query string, values []driver.Value) error {
+			if strings.HasPrefix(query, "INSERT") {
+				body, _ := values[7].(string)
+				if body == "empty ServiceName" {
+					require.Equal(t, "", values[6])
+				} else {
+					require.Equal(t, "test-service", values[6])
+				}
+			}
+			return nil
+		})
+
+		exporter := newTestLogsExporter(t, defaultEndpoint)
+		mustPushLogsData(t, exporter, multipleLogsWithDifferentServiceName(1))
+	})
 }
 
 func TestLogsClusterConfig(t *testing.T) {
@@ -215,6 +231,30 @@ func simpleLogsWithNoTimestamp(count int) plog.Logs {
 	return logs
 }
 
+func multipleLogsWithDifferentServiceName(count int) plog.Logs {
+	logs := simpleLogs(count)
+	rl := logs.ResourceLogs().AppendEmpty()
+	rl.SetSchemaUrl("https://opentelemetry.io/schemas/1.4.0")
+	sl := rl.ScopeLogs().AppendEmpty()
+	sl.SetSchemaUrl("https://opentelemetry.io/schemas/1.7.0")
+	sl.Scope().SetName("io.opentelemetry.contrib.clickhouse")
+	sl.Scope().SetVersion("1.0.0")
+	sl.Scope().Attributes().PutStr("lib", "clickhouse")
+	timestamp := time.Unix(1703498029, 0)
+	for i := 0; i < count; i++ {
+		r := sl.LogRecords().AppendEmpty()
+		r.SetObservedTimestamp(pcommon.NewTimestampFromTime(timestamp))
+		r.SetSeverityNumber(plog.SeverityNumberError2)
+		r.SetSeverityText("error")
+		r.Body().SetStr("empty ServiceName")
+		r.Attributes().PutStr(conventions.AttributeServiceNamespace, "default")
+		r.SetFlags(plog.DefaultLogRecordFlags)
+		r.SetTraceID([16]byte{1, 2, 3, byte(i)})
+		r.SetSpanID([8]byte{1, 2, 3, byte(i)})
+	}
+	return logs
+}
+
 func mustPushLogsData(t *testing.T, exporter *logsExporter, ld plog.Logs) {
 	err := exporter.pushLogsData(context.TODO(), ld)
 	require.NoError(t, err)