a6-plugin-kafka-logger

Overview

The kafka-logger plugin pushes request/response logs to Apache Kafka topics. It supports multiple brokers, SASL authentication, async/sync producing, custom log formats, and batch processing for efficient delivery.

When to Use

• Stream access logs to Kafka for downstream processing
• Feed real-time API analytics pipelines
• Integrate with Kafka-based logging infrastructure
• Need SASL-authenticated Kafka clusters

Plugin Configuration Reference

Core Parameters

Field	Type	Required	Default	Description
brokers	array	Yes	—	Kafka broker list
brokers[].host	string	Yes	—	Broker hostname or IP
brokers[].port	integer	Yes	—	Broker port (1-65535)
kafka_topic	string	Yes	—	Target Kafka topic
key	string	No	—	Partition key for routing
timeout	integer	No	3	Connection timeout in seconds

SASL Authentication

Field	Type	Required	Default	Description
brokers[].sasl_config	object	No	—	SASL config per broker
brokers[].sasl_config.mechanism	string	No	"PLAIN"	PLAIN, SCRAM-SHA-256, or SCRAM-SHA-512
brokers[].sasl_config.user	string	Yes*	—	SASL username (*if sasl_config set)
brokers[].sasl_config.password	string	Yes*	—	SASL password (*if sasl_config set)

Producer Configuration

Field	Type	Default	Description
producer_type	string	"async"	async (batched) or sync (immediate)
required_acks	integer	1	1 (leader ack) or -1 (all replicas)
producer_batch_num	integer	200	Messages per Kafka batch
producer_batch_size	integer	1048576	Batch size in bytes (1MB)
producer_max_buffering	integer	50000	Max buffered messages
producer_time_linger	integer	1	Flush interval in seconds
meta_refresh_interval	integer	30	Kafka metadata refresh in seconds
cluster_name	integer	1	Cluster identifier (for multi-cluster)

Log Format Options

Field	Type	Default	Description
meta_format	string	"default"	default (JSON) or origin (raw HTTP)
log_format	object	—	Custom log format with $variable syntax
include_req_body	boolean	false	Include request body
include_req_body_expr	array	—	Conditional request body logging
include_resp_body	boolean	false	Include response body
include_resp_body_expr	array	—	Conditional response body logging
max_req_body_bytes	integer	524288	Max request body size to log (512KB)
max_resp_body_bytes	integer	524288	Max response body size to log (512KB)

Batch Processing Parameters

Field	Type	Default	Description
batch_max_size	integer	1000	Max entries per batch
inactive_timeout	integer	5	Seconds before flushing incomplete batch
buffer_duration	integer	60	Max age of oldest entry
max_retry_count	integer	0	Retry attempts on failure
retry_delay	integer	1	Seconds between retries

Step-by-Step: Ship Logs to Kafka

1. Create a route with kafka-logger

a6 route create -f - <<'EOF'
{
  "id": "kafka-logged-api",
  "uri": "/api/*",
  "plugins": {
    "kafka-logger": {
      "brokers": [
        {"host": "kafka-1", "port": 9092},
        {"host": "kafka-2", "port": 9092}
      ],
      "kafka_topic": "apisix-logs",
      "batch_max_size": 100
    }
  },
  "upstream": {
    "type": "roundrobin",
    "nodes": {
      "backend:8080": 1
    }
  }
}
EOF

2. Verify messages in Kafka

kafka-console-consumer --bootstrap-server kafka-1:9092 --topic apisix-logs --from-beginning

Common Patterns

SASL-authenticated Kafka cluster

{
  "plugins": {
    "kafka-logger": {
      "brokers": [
        {
          "host": "kafka.example.com",
          "port": 9092,
          "sasl_config": {
            "mechanism": "SCRAM-SHA-256",
            "user": "apisix",
            "password": "secret"
          }
        }
      ],
      "kafka_topic": "api-logs",
      "required_acks": -1
    }
  }
}

Custom log format

{
  "plugins": {
    "kafka-logger": {
      "brokers": [{"host": "kafka", "port": 9092}],
      "kafka_topic": "api-logs",
      "log_format": {
        "@timestamp": "$time_iso8601",
        "client_ip": "$remote_addr",
        "method": "$request_method",
        "uri": "$request_uri",
        "status": "$status",
        "latency": "$request_time",
        "upstream": "$upstream_addr"
      }
    }
  }
}

Partition by route ID

{
  "plugins": {
    "kafka-logger": {
      "brokers": [{"host": "kafka", "port": 9092}],
      "kafka_topic": "api-logs",
      "key": "$route_id"
    }
  }
}

High-throughput tuning

{
  "plugins": {
    "kafka-logger": {
      "brokers": [
        {"host": "kafka-1", "port": 9092},
        {"host": "kafka-2", "port": 9092},
        {"host": "kafka-3", "port": 9092}
      ],
      "kafka_topic": "api-logs",
      "producer_type": "async",
      "producer_batch_num": 500,
      "producer_batch_size": 2097152,
      "producer_max_buffering": 100000,
      "producer_time_linger": 2,
      "batch_max_size": 5000,
      "inactive_timeout": 10,
      "required_acks": 1
    }
  }
}

Raw HTTP log format

{
  "plugins": {
    "kafka-logger": {
      "brokers": [{"host": "kafka", "port": 9092}],
      "kafka_topic": "raw-logs",
      "meta_format": "origin"
    }
  }
}

Produces raw HTTP request text instead of JSON.

Config Sync Example

version: "1"
routes:
  - id: kafka-logged-api
    uri: /api/*
    plugins:
      kafka-logger:
        brokers:
          - host: kafka-1
            port: 9092
          - host: kafka-2
            port: 9092
        kafka_topic: apisix-logs
        producer_type: async
        required_acks: 1
        batch_max_size: 200
        inactive_timeout: 5
    upstream_id: my-upstream

Troubleshooting

Symptom	Cause	Fix
No messages in Kafka	Broker unreachable	Verify broker host/port; check firewall
SASL auth failure	Wrong credentials or mechanism	Verify user/password; ensure mechanism matches Kafka config
Messages delayed	Large batch/timeout settings	Reduce inactive_timeout and producer_time_linger
Messages dropped	Buffer overflow	Increase producer_max_buffering; add more brokers
Topic not found	Topic doesn't exist and auto-create disabled	Create topic manually or enable auto.create.topics.enable
High latency	required_acks: -1 with slow replicas	Use required_acks: 1 for lower latency (less durability)

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This page is generated from a6-plugin-kafka-logger/SKILL.md in the api7/a6 repository. Browse all skills on the AI Agent Skills page.