Add changelog entry, return early when only one kafka instance is set

Signed-off-by: Paschalis Tsilias <[email protected]>

CHANGELOG.md

@@ -22,6 +22,8 @@ Main (unreleased)
 - Fix an issue in `remote.s3` where the exported content of an object would be an empty string if `remote.s3` failed to fully retrieve
   the file in a single read call. (@grafana/agent-squad)
 
+- Utilize the `instance` Argument of `prometheus.exporter.kafka` when set. (@akhmatov-s)
+
 ### Other changes
 
 - Removed support for Windows 2012 in line with Microsoft end of life. (@mattdurham)

pkg/integrations/kafka_exporter/kafka_exporter.go

@@ -107,15 +107,19 @@ func (c *Config) UnmarshalYAML(unmarshal func(interface{}) error) error {
 func (c *Config) Name() string {
 	return "kafka_exporter"
 }
+
 // InstanceKey returns the hostname:port of the first Kafka node, if any. If
 // there is not exactly one Kafka node, the user must manually provide
 // their own value for instance key in the common config.
 func (c *Config) InstanceKey(agentKey string) (string, error) {
+	if len(c.KafkaURIs) == 1 {
+		return c.KafkaURIs[0], nil
+	}
 	if c.Instance == "" && len(c.KafkaURIs) > 1 {
 		return "", fmt.Errorf("an automatic value for `instance` cannot be determined from %d kafka servers, manually provide one for this integration", len(c.KafkaURIs))
 	}
 
-	return c.KafkaURIs[0], nil
+	return c.Instance, nil
 }
 
 // NewIntegration creates a new elasticsearch_exporter