Fix nil reference panic due to variable shadowing bug

.chloggen/fix-clickhouse-json-exporter-factory.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. receiver/filelog)
+component: exporter/clickhouse
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Fix a bug in the exporter factory resulting in a nil dereference panic when the clickhouse.json feature gate is enabled
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [43733]
+
+# (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/clickhouseexporter/exporter_logs_json.go

@@ -18,6 +18,13 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/clickhouseexporter/internal/sqltemplates"
 )
 
+// anyLogsExporter is an interface that satisfies both the default map logsExporter and the logsJSONExporter
+type anyLogsExporter interface {
+	start(context.Context, component.Host) error
+	shutdown(context.Context) error
+	pushLogsData(context.Context, plog.Logs) error
+}
+
 type logsJSONExporter struct {
 	cfg       *Config
 	logger    *zap.Logger

exporter/clickhouseexporter/exporter_traces_json.go

@@ -18,6 +18,13 @@ import (
 	"github.com/open-telemetry/opentelemetry-collector-contrib/exporter/clickhouseexporter/internal/sqltemplates"
 )
 
+// anyTracesExporter is an interface that satisfies both the default map tracesExporter and the tracesJSONExporter
+type anyTracesExporter interface {
+	start(context.Context, component.Host) error
+	shutdown(context.Context) error
+	pushTraceData(ctx context.Context, td ptrace.Traces) error
+}
+
 type tracesJSONExporter struct {
 	cfg       *Config
 	logger    *zap.Logger

exporter/clickhouseexporter/factory.go

@@ -37,19 +37,19 @@ func createLogsExporter(
 	c := cfg.(*Config)
 	c.collectorVersion = set.BuildInfo.Version
 
-	exp := newLogsExporter(set.Logger, c)
-	startOpt := exporterhelper.WithStart(exp.start)
+	var exp anyLogsExporter
 	if featureGateJSON.IsEnabled() {
-		exp := newLogsJSONExporter(set.Logger, c)
-		startOpt = exporterhelper.WithStart(exp.start)
+		exp = newLogsJSONExporter(set.Logger, c)
+	} else {
+		exp = newLogsExporter(set.Logger, c)
 	}
 
 	return exporterhelper.NewLogs(
 		ctx,
 		set,
 		cfg,
 		exp.pushLogsData,
-		startOpt,
+		exporterhelper.WithStart(exp.start),
 		exporterhelper.WithShutdown(exp.shutdown),
 		exporterhelper.WithTimeout(c.TimeoutSettings),
 		exporterhelper.WithQueue(c.QueueSettings),
@@ -65,19 +65,19 @@ func createTracesExporter(
 	c := cfg.(*Config)
 	c.collectorVersion = set.BuildInfo.Version
 
-	exp := newTracesExporter(set.Logger, c)
-	startOpt := exporterhelper.WithStart(exp.start)
+	var exp anyTracesExporter
 	if featureGateJSON.IsEnabled() {
-		exp := newTracesJSONExporter(set.Logger, c)
-		startOpt = exporterhelper.WithStart(exp.start)
+		exp = newTracesJSONExporter(set.Logger, c)
+	} else {
+		exp = newTracesExporter(set.Logger, c)
 	}
 
 	return exporterhelper.NewTraces(
 		ctx,
 		set,
 		cfg,
 		exp.pushTraceData,
-		startOpt,
+		exporterhelper.WithStart(exp.start),
 		exporterhelper.WithShutdown(exp.shutdown),
 		exporterhelper.WithTimeout(c.TimeoutSettings),
 		exporterhelper.WithQueue(c.QueueSettings),