[exporter/kafka] franz-go ignores deprecated TLS config syntax

[alont]

Component(s)

exporter/kafka

What happened?

Description

The Kafka Exporter configuration syntax:

auth:
  tls:
    ...

...was deprecated in v0.124.0, in favor of:

tls:
  ...

The Sarama Kafka client accepts both syntaxes, but the franz-go client ignores the deprecated syntax and silently falls back to a non-TLS connection.

Steps to Reproduce

1. Set up a TLS-enabled Kafka broker
2. Run otel-collector with the attached configuration file
3. Wait 30 seconds

Expected Result

otel-collector metrics published to the mytopic topic, and the log should show something like:

2025-09-17T19:27:17.262-0400    debug   kafkaexporter@v0.135.0/kafka_exporter.go:176    kafka records exported  {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "records": 1, "topic": "mytopic"}
2025-09-17T19:27:28.683-0400    debug   franz   kzap@v1.1.2/kzap.go:110 reaped connections      {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "time_since_last_reap": 19.9999845, "reap_dur": 0.000564291, "num_reaped": 1}

Actual Result

No otel-collector metrics published to the mytopic topic, and the log shows "err": "EOF" errors:

d": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "broker": "seed_0", "bytes_read": 0, "read_wait": 0.000055792, "time_to_read": 0.1213485, "err": "EOF"}
2025-09-17T19:22:34.709-0400    debug   franz   kzap@v1.1.2/kzap.go:110 connection initialization failed        {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "addr": "localhost:9092", "broker": "seed_0", "err": "EOF"}
2025-09-17T19:22:34.709-0400    info    franz   kzap@v1.1.2/kzap.go:114 new topic metadata wait failed, retrying wait   {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "topic": "mytopic", "err": "EOF"}
2025-09-17T19:22:34.959-0400    info    franz   kzap@v1.1.2/kzap.go:114 metadata update triggered       {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "why": "re-updating metadata due to err: EOF"}

Collector version

v0.135.0

Environment information

Environment

OS: macOS Sequoia 15.5, Ubuntu 22.04,
Compiler: 1.24.7

OpenTelemetry Collector configuration

receivers:
  prometheus/otel:
    config:
      scrape_configs:
        - job_name: otel
          scrape_interval: 15s
          static_configs:
            - targets:
              - 0.0.0.0:8888
exporters:
  kafka:
    protocol_version: 2.1.0
    encoding: otlp_proto
    topic: mytopic
    brokers:
      - localhost:9092
    auth:
      tls:
        ca_file: ca_chain.pem
        cert_file: certificate.pem
        key_file: private_key.pem
service:
  telemetry:
    logs:
      level: "debug"
  pipelines:
    metrics:
      receivers:
        - prometheus/otel
      exporters:
        - kafka

Log output

d": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "broker": "seed_0", "bytes_read": 0, "read_wait": 0.000055792, "time_to_read": 0.1213485, "err": "EOF"}
2025-09-17T19:22:34.709-0400    debug   franz   kzap@v1.1.2/kzap.go:110 connection initialization failed        {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "addr": "localhost:9092", "broker": "seed_0", "err": "EOF"}
2025-09-17T19:22:34.709-0400    info    franz   kzap@v1.1.2/kzap.go:114 new topic metadata wait failed, retrying wait   {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "topic": "mytopic", "err": "EOF"}
2025-09-17T19:22:34.959-0400    info    franz   kzap@v1.1.2/kzap.go:114 metadata update triggered       {"resource": {"service.instance.id": "55555555-5555-5555-5555-555555555555", "service.name": "otelcontribcol", "service.version": "0.135.0-dev"}, "otelcol.component.id": "kafka", "otelcol.component.kind": "exporter", "otelcol.signal": "metrics", "why": "re-updating metadata due to err: EOF"}

Additional context

No response

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[github-actions]

Pinging code owners:

• exporter/kafka: @pavolloffay @MovieStoreGuy @axw

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[axw]

Thanks for reporting this, and fixing it!