Configuration

Environment Variables

Core Configuration

Variable	Description	Default
KAFKA_NODE_ID	Unique node identifier	1
KAFKA_PROCESS_ROLES	Comma-separated roles: broker, controller	broker,controller
KAFKA_CLUSTER_ID	Cluster identifier (must be same on all nodes)	Auto-generated
KAFKA_CONTROLLER_QUORUM_VOTERS	Controller quorum voters (format: id@host:port[,...])	1@localhost:9093
KAFKA_CONTROLLER_LISTENER_NAMES	Controller listener name	CONTROLLER

Network Configuration

Variable	Description	Default
KAFKA_LISTENERS	Listener configuration	PLAINTEXT://:9092,CONTROLLER://:9093
KAFKA_ADVERTISED_LISTENERS	Advertised listeners for clients	PLAINTEXT://localhost:9092
KAFKA_INTER_BROKER_LISTENER_NAME	Inter-broker listener name	PLAINTEXT
KAFKA_LISTENER_SECURITY_PROTOCOL_MAP	Security protocol mapping	CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT,...

Performance Configuration

Variable	Description	Default
KAFKA_NUM_NETWORK_THREADS	Number of network threads	3
KAFKA_NUM_IO_THREADS	Number of I/O threads	8
KAFKA_NUM_PARTITIONS	Default number of partitions	1
KAFKA_NUM_RECOVERY_THREADS_PER_DATA_DIR	Recovery threads per data dir	1
KAFKA_SOCKET_SEND_BUFFER_BYTES	Socket send buffer size	102400
KAFKA_SOCKET_RECEIVE_BUFFER_BYTES	Socket receive buffer size	102400
KAFKA_SOCKET_REQUEST_MAX_BYTES	Max socket request size	104857600

Storage Configuration

Variable	Description	Default
KAFKA_LOG_DIRS	Log directories	/opt/kafka/data
KAFKA_LOG_RETENTION_HOURS	Log retention period (hours)	168
KAFKA_LOG_SEGMENT_BYTES	Log segment size	1073741824
KAFKA_LOG_RETENTION_CHECK_INTERVAL_MS	Retention check interval	300000

Replication Configuration

Variable	Description	Default
KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR	Offsets topic replication factor	1
KAFKA_TRANSACTION_STATE_LOG_REPLICATION_FACTOR	Transaction log replication factor	1
KAFKA_TRANSACTION_STATE_LOG_MIN_ISR	Minimum in-sync replicas	1

Topic Configuration

Variable	Description	Default
KAFKA_AUTO_CREATE_TOPICS_ENABLE	Auto-create topics	true
KAFKA_DELETE_TOPIC_ENABLE	Allow topic deletion	true
KAFKA_GROUP_INITIAL_REBALANCE_DELAY_MS	Group rebalance delay	0

Custom Properties

Any Kafka property can be set using the KAFKA_CONFIG_ prefix:

environment:
  KAFKA_CONFIG_LOG_CLEANER_ENABLE: "true"
  KAFKA_CONFIG_LOG_RETENTION_BYTES: "1073741824"
  KAFKA_CONFIG_MAX_REQUEST_SIZE: "10485760"
  KAFKA_CONFIG_MESSAGE_MAX_BYTES: "1048588"
  KAFKA_CONFIG_REPLICA_FETCH_MAX_BYTES: "1048576"
  KAFKA_CONFIG_MAX_CONNECTIONS_PER_IP: "2147483647"

This translates to:

• log.cleaner.enable=true
• log.retention.bytes=1073741824
• max.request.size=10485760
• message.max.bytes=1048588
• replica.fetch.max.bytes=1048576
• max.connections.per.ip=2147483647

Listener Configuration Example

For multiple listener configurations:

environment:
  KAFKA_LISTENERS: "PLAINTEXT://:9092,CONTROLLER://:9093"
  KAFKA_ADVERTISED_LISTENERS: "PLAINTEXT://kafka:9092"
  KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: "CONTROLLER:PLAINTEXT,PLAINTEXT:PLAINTEXT"
  KAFKA_INTER_BROKER_LISTENER_NAME: "PLAINTEXT"