Troubleshooting Kafka

Offset Out Of Range Error

Exception: KafkaError{code=OFFSET_OUT_OF_RANGE,val=1,str="Broker: Offset out of range"}

This happens where Kafka and the consumers get out of sync. Possible reasons are:

1. Running out of disk space or memory
2. Having a sustained event spike that causes very long processing times, causing Kafka to drop messages as they go past the retention time
3. Date/time out of sync issues due to a restart or suspend/resume cycle

Visualize

You can visualize the Kafka consumers and their offsets by bringing an additional container, such as Kafka UI or Redpanda Console into your Docker Compose.

Kafka UI:

kafka-ui:
  image: provectuslabs/kafka-ui:latest
  restart: on-failure
  environment:
    KAFKA_CLUSTERS_0_NAME: "local"
    KAFKA_CLUSTERS_0_BOOTSTRAPSERVERS: "kafka:9092"
    DYNAMIC_CONFIG_ENABLED: "true"
  ports:
    - "8080:8080"
  depends_on:
    - kafka

Or, you can use Redpanda Console:

redpanda-console:
  image: docker.redpanda.com/redpandadata/console:latest
  restart: on-failure
  entrypoint: /bin/sh
  command: -c "echo \"$$CONSOLE_CONFIG_FILE\" > /tmp/config.yml; /app/console"
  environment:
    CONFIG_FILEPATH: "/tmp/config.yml"
    CONSOLE_CONFIG_FILE: |
      kafka:
        brokers: ["kafka:9092"]
        sasl:
          enabled: false
      schemaRegistry:
        enabled: false
      kafkaConnect:
        enabled: false
  ports:
    - "8080:8080"
  depends_on:
    - kafka

Ideally, you want to have zero lag for all consumer groups. If a consumer group has a lot of lag, you need to investigate whether it's caused by a disconnected consumer (e.g., a Sentry/Snuba container that's disconnected from Kafka) or a consumer that's stuck processing a certain message. If it's a disconnected consumer, you can either restart the container or reset the Kafka offset to 'earliest.' Otherwise, you can reset the Kafka offset to 'latest.'

Recovery

Proper solution

The proper solution is as follows (reported by @rmisyurev). This example uses snuba-consumers with events topic. Your consumer group name and topic name may be different.

1. Shutdown the corresponding Sentry/Snuba container that's using the consumer group (You can see the corresponding containers by inspecting the docker-compose.yml file):
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   docker compose stop snuba-errors-consumer snuba-outcomes-consumer snuba-outcomes-billing-consumer
   

2. Receive consumers list:
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   docker compose run --rm kafka kafka-consumer-groups --bootstrap-server kafka:9092 --list
   

3. Get group info:
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   docker compose run --rm kafka kafka-consumer-groups --bootstrap-server kafka:9092 --group snuba-consumers --describe
   

4. Watching what is going to happen with offset by using dry-run (optional):
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   docker compose run --rm kafka kafka-consumer-groups --bootstrap-server kafka:9092 --group snuba-consumers --topic events --reset-offsets --to-latest --dry-run
   

5. Set offset to latest and execute:
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   docker compose run --rm kafka kafka-consumer-groups --bootstrap-server kafka:9092 --group snuba-consumers --topic events --reset-offsets --to-latest --execute
   

6. Start the previously stopped Sentry/Snuba containers:
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   docker compose start snuba-errors-consumer snuba-outcomes-consumer snuba-outcomes-billing-consumer
   

Another option

This option is as follows (reported by @gabn88):

1. Set offset to latest and execute:
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   docker compose run --rm kafka kafka-consumer-groups --bootstrap-server kafka:9092 --all-groups --all-topics --reset-offsets --to-latest --execute
   

Unlike the proper solution, this involves resetting the offsets of all consumer groups and all topics.

Nuclear option

The nuclear option is removing all Kafka-related volumes and recreating them which will cause data loss. Any data that was pending there will be gone upon deleting these volumes.

1. Stop the instance:

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   docker compose down --volumes
   

2. Remove the the Kafka volume:

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   docker volume rm sentry-kafka
   

3. Run the install script again:

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   ./install.sh
   

4. Start the instance:

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   docker compose up --wait
   

Reducing disk usage

If you want to reduce the disk space used by Kafka, you'll need to carefully calculate how much data you are ingesting, how much data loss you can tolerate and then follow the recommendations on this awesome StackOverflow post or this post on our community forum.

You could, however, add these on the Kafka container's environment variables (by @csvan):

services:
  kafka:
    # ...
    environment:
      KAFKA_LOG_RETENTION_HOURS: 24
      KAFKA_LOG_CLEANER_ENABLE: true
      KAFKA_LOG_CLEANUP_POLICY: delete