Kafka Receiver and Exporter: use same default value for topic setting

[andreasgerstmayr]

Component(s)

exporter/kafka, receiver/kafka

Describe the issue you're reporting

For the Kafka receiver, the default topic is always otlp_spans:

opentelemetry-collector-contrib/receiver/kafkareceiver/factory.go

Line 20 in c506b4e

defaultTopic = "otlp_spans"

opentelemetry-collector-contrib/receiver/kafkareceiver/factory.go

Line 93 in c506b4e

Topic: defaultTopic,

For the Kafka exporter, the default topic is otlp_spans for traces, otlp_metrics for metrics, otlp_logs for logs:

opentelemetry-collector-contrib/exporter/kafkaexporter/factory.go

Line 96 in c506b4e

// using an empty topic to track when it has not been set by user, default is based on traces or metrics.

opentelemetry-collector-contrib/exporter/kafkaexporter/factory.go

Line 158 in c506b4e

oCfg.Topic = defaultMetricsTopic

The default values should be identical for the Kafka receiver and exporter.

[github-actions]

Pinging code owners:

• exporter/kafka: @pavolloffay @MovieStoreGuy
• receiver/kafka: @pavolloffay @MovieStoreGuy

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[github-actions]

This issue has been inactive for 60 days. It will be closed in 60 days if there is no activity. To ping code owners by adding a component label, see Adding Labels via Comments, or if you are unsure of which component this issue relates to, please ping @open-telemetry/collector-contrib-triagers. If this issue is still relevant, please ping the code owners or leave a comment explaining why it is still relevant. Otherwise, please close it.

Pinging code owners:

• exporter/kafka: @pavolloffay @MovieStoreGuy
• receiver/kafka: @pavolloffay @MovieStoreGuy

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[jwafle]

Hi @andreasgerstmayr, @MovieStoreGuy! Decided to take up this issue on a Thursday since I was bored and it seemed fairly trivial. Note sure if there are concerns about breaking users pipelines, but I would assume if they are using the Kafka receiver for metrics/logs already, they likely must have configured the topic name to not be "otlp_spans" already.

[pavolloffay]

+1

[andreasgerstmayr]

Awesome, thanks @jwafle!