kafka

Kafka & Rapids & Rivers Skill

Patterns, templates, and procedures for building event-driven systems with Kafka on Nais. Covers Rapids & Rivers framework, event schema design, and consumer/producer patterns.

When to Use

• Setting up Kafka in a Nais application
• Implementing a Rapids & Rivers consumer (River)
• Designing event schemas
• Testing event-driven code with TestRapid
• Troubleshooting Kafka connectivity or consumer lag

Commands

# Check Kafka env vars are present (names only, not values)
kubectl exec -it <pod> -n <namespace> -- env | grep -o '^KAFKA[^=]*'

# Verify Kafka credentials are mounted
kubectl exec -it <pod> -n <namespace> -- ls -la /var/run/secrets/nais.io/kafka/

# View pod logs for Kafka events
kubectl logs -n <namespace> <pod> --tail=50 | grep -i "event\|kafka\|river"

Setting Up Kafka

Nais Manifest

apiVersion: nais.io/v1alpha1
kind: Application
metadata:
  name: my-app
spec:
  kafka:
    pool: nav-dev # or nav-prod

This automatically:

• Creates Kafka credentials
• Mounts credentials in /var/run/secrets/nais.io/kafka/
• Provides environment variables

Configuration

// Environment variables automatically set by Nais
val kafkaConfig = mapOf(
    "KAFKA_BROKERS" to System.getenv("KAFKA_BROKERS"),
    "KAFKA_TRUSTSTORE_PATH" to System.getenv("KAFKA_TRUSTSTORE_PATH"),
    "KAFKA_CREDSTORE_PASSWORD" to System.getenv("KAFKA_CREDSTORE_PASSWORD"),
    "KAFKA_KEYSTORE_PATH" to System.getenv("KAFKA_KEYSTORE_PATH"),
    "KAFKA_CONSUMER_GROUP_ID" to "my-app-v1",
    "KAFKA_RAPID_TOPIC" to "teamname.rapid-v1"
)

Rapids & Rivers

Core Concepts

• Rapid: The Kafka topic where all events flow
• River: A consumer that listens to specific event types
• Need: A request for data/action
• Demand: Required fields in an event
• Require: Required values in an event
• Reject: Conditions that exclude an event
• Interested In: Optional fields to capture

Application Setup