kafka-logger

Description

The kafka-logger Plugin pushes request and response logs as JSON objects to Apache Kafka clusters in batches and supports the customization of log formats.

It might take some time to receive the log data. It will be automatically sent after the timer function in the batch processor expires.

Attributes

Name	Type	Required	Default	Valid values	Description
broker_list	object	False			Deprecated, use brokers instead. List of Kafka brokers (nodes).
brokers	array	True			List of Kafka brokers (nodes).
brokers.host	string	True			The host of Kafka broker, e.g. 192.168.1.1.
brokers.port	integer	True		[1, 65535]	The port of Kafka broker.
brokers.sasl_config	object	False			The SASL config of Kafka broker.
brokers.sasl_config.mechanism	string	False	"PLAIN"	["PLAIN", "SCRAM-SHA-256", "SCRAM-SHA-512"]	The mechanism of SASL config.
brokers.sasl_config.user	string	True			The user of sasl_config. Required if sasl_config is configured.
brokers.sasl_config.password	string	True			The password of sasl_config. Required if sasl_config is configured.
kafka_topic	string	True			Target topic to push the logs.
producer_type	string	False	async	["async", "sync"]	Message sending mode of the producer.
required_acks	integer	False	1	[1, -1]	Number of acknowledgements the leader needs to receive for the producer to consider the request complete. This controls the durability of the sent records. The attribute follows the same configuration as the Kafka acks attribute. required_acks cannot be 0. See Apache Kafka documentation for more.
key	string	False			Key used for allocating partitions for messages.
timeout	integer	False	3	[1,...]	Timeout in seconds for the upstream to send data.
name	string	False	"kafka logger"		Unique identifier for the batch processor. If you use Prometheus to monitor APISIX metrics, the name is exported in apisix_batch_process_entries.
meta_format	enum	False	"default"	["default","origin"]	Format to collect the request information. Setting to default collects the information in JSON format and origin collects the information with the original HTTP request. See examples below.
log_format	object	False			Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, APISIX or NGINX variables can be referenced by prefixing with $.
include_req_body	boolean	False	false	[false, true]	When set to true includes the request body in the log. If the request body is too big to be kept in the memory, it can't be logged due to NGINX's limitations.
include_req_body_expr	array	False			Filter for when the include_req_body attribute is set to true. Request body is only logged when the expression set here evaluates to true. See lua-resty-expr for more.
max_req_body_bytes	integer	False	524288	>=1	Maximum request body size in bytes to push to Kafka. If the size exceeds the configured value, the body will be truncated before being pushed.
include_resp_body	boolean	False	false	[false, true]	When set to true includes the response body in the log.
include_resp_body_expr	array	False			Filter for when the include_resp_body attribute is set to true. Response body is only logged when the expression set here evaluates to true. See lua-resty-expr for more.
max_resp_body_bytes	integer	False	524288	>=1	Maximum response body size in bytes to push to Kafka. If the size exceeds the configured value, the body will be truncated before being pushed.
cluster_name	integer	False	1	[1,...]	Name of the cluster. Used when there are two or more Kafka clusters. Only works if the producer_type attribute is set to async.
producer_batch_num	integer	False	200	[1,...]	batch_num parameter in lua-resty-kafka. Merges messages and sends them in batches. Unit is message count.
producer_batch_size	integer	False	1048576	[0,...]	batch_size parameter in lua-resty-kafka in bytes.
producer_max_buffering	integer	False	50000	[1,...]	max_buffering parameter in lua-resty-kafka representing maximum buffer size. Unit is message count.
producer_time_linger	integer	False	1	[1,...]	flush_time parameter in lua-resty-kafka in seconds.
meta_refresh_interval	integer	False	30	[1,...]	refresh_interval parameter in lua-resty-kafka that specifies the interval to auto-refresh the metadata, in seconds.

This Plugin supports using batch processors to aggregate and process entries (logs/data) in a batch. This avoids the need for frequently submitting the data. The batch processor submits data every 5 seconds or when the data in the queue reaches 1000. See Batch Processor for more information or setting your custom configuration.

IMPORTANT

The data is first written to a buffer. When the buffer exceeds the batch_max_size or buffer_duration attribute, the data is sent to the Kafka server and the buffer is flushed.

If the process is successful, it will return true and if it fails, returns nil with a string with the "buffer overflow" error.

meta_format example

• default:

  {
    "upstream": "127.0.0.1:1980",
    "start_time": 1619414294760,
    "client_ip": "127.0.0.1",
    "service_id": "",
    "route_id": "1",
    "request": {
      "querystring": {
        "ab": "cd"
      },
      "size": 90,
      "uri": "/hello?ab=cd",
      "url": "http://localhost:1984/hello?ab=cd",
      "headers": {
        "host": "localhost",
        "content-length": "6",
        "connection": "close"
      },
      "body": "abcdef",
      "method": "GET"
    },
    "response": {
      "headers": {
        "connection": "close",
        "content-type": "text/plain; charset=utf-8",
        "date": "Mon, 26 Apr 2021 05:18:14 GMT",
        "server": "APISIX/2.5",
        "transfer-encoding": "chunked"
      },
      "size": 190,
      "status": 200
    },
    "server": {
      "hostname": "localhost",
      "version": "2.5"
    },
    "latency": 0
  }

• origin:

  GET /hello?ab=cd HTTP/1.1
  host: localhost
  content-length: 6
  connection: close
  
  abcdef

Metadata

You can also set the format of the logs by configuring the Plugin metadata. The following configurations are available:

Name	Type	Required	Default	Description
log_format	object	False		Log format declared as key-value pairs in JSON. Values support strings and nested objects (up to five levels deep; deeper fields are truncated). Within strings, APISIX or NGINX variables can be referenced by prefixing with $.
max_pending_entries	integer	False		Maximum number of pending entries that can be buffered in the batch processor before it starts dropping them.

IMPORTANT

Configuring the Plugin metadata is global in scope. This means that it will take effect on all Routes and Services which use the kafka-logger Plugin.

Examples

The examples below demonstrate how to configure the kafka-logger Plugin for different use cases.

To follow along the examples, start a sample Kafka cluster using Docker Compose:

docker-compose.yml

services:
  zookeeper:
    image: confluentinc/cp-zookeeper:7.8.0
    container_name: zookeeper
    environment:
      ZOOKEEPER_CLIENT_PORT: 2181
      ZOOKEEPER_TICK_TIME: 2000

  kafka:
    image: confluentinc/cp-kafka:7.8.0
    container_name: kafka
    depends_on:
      - zookeeper
    environment:
      KAFKA_BROKER_ID: 1
      KAFKA_ZOOKEEPER_CONNECT: zookeeper:2181
      KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
      KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:29092,PLAINTEXT_HOST://127.0.0.1:9092
      KAFKA_OFFSETS_TOPIC_REPLICATION_FACTOR: 1
      KAFKA_AUTO_CREATE_TOPICS_ENABLE: "true"
    ports:
      - "9092:9092"

Start containers:

docker compose up -d

note

You can fetch the admin_key from config.yaml and save to an environment variable with the following command:

admin_key=$(yq '.deployment.admin.admin_key[0].key' conf/config.yaml | sed 's/"//g')

Log in Different Meta Log Formats

The following example demonstrates how to enable the kafka-logger Plugin on a Route, which logs client requests and pushes logs to Kafka. You will also understand the differences between the default and origin meta log formats.

In a separate terminal, wait for messages in the configured Kafka topic:

docker exec -it kafka kafka-console-consumer --bootstrap-server localhost:9092 --topic test2 --from-beginning

Open a new terminal session for the following steps.

Create a Route with kafka-logger. Set meta_format to the default log format, and set batch_max_size to 1 to send the log entry immediately:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "kafka-logger-route",
    "uri": "/get",
    "plugins": {
      "kafka-logger": {
        "meta_format": "default",
        "brokers": [
          {
            "host": "127.0.0.1",
            "port": 9092
          }
        ],
        "kafka_topic": "test2",
        "key": "key1",
        "batch_max_size": 1
      }
    },
    "upstream": {
      "nodes": {
        "httpbin.org:80": 1
      },
      "type": "roundrobin"
    }
  }'

Send a request to the Route to generate a log entry:

curl -i "http://127.0.0.1:9080/get"

You should see an HTTP/1.1 200 OK response.

You should see a log entry in the Kafka topic similar to the following:

{
  "latency": 411.00001335144,
  "request": {
    "querystring": {},
    "headers": {
      "host": "127.0.0.1:9080",
      "user-agent": "curl/8.7.1",
      "accept": "*/*",
      "x-forwarded-proto": "http",
      "x-forwarded-host": "127.0.0.1",
      "x-forwarded-port": "9080"
    },
    "method": "GET",
    "size": 83,
    "uri": "/get",
    "url": "http://127.0.0.1:9080/get"
  },
  "response": {
    "headers": {
      "content-length": "233",
      "access-control-allow-credentials": "true",
      "content-type": "application/json",
      "connection": "close",
      "access-control-allow-origin": "*",
      "date": "Fri, 10 Nov 2023 06:02:44 GMT",
      "server": "APISIX/3.16.0"
    },
    "status": 200,
    "size": 475
  },
  "route_id": "kafka-logger-route",
  "client_ip": "127.0.0.1",
  "server": {
    "hostname": "apisix",
    "version": "3.16.0"
  },
  "apisix_latency": 18.00001335144,
  "service_id": "",
  "upstream_latency": 393,
  "start_time": 1699596164550,
  "upstream": "54.90.18.68:80"
}

Update the meta log format to origin:

curl "http://127.0.0.1:9180/apisix/admin/routes/kafka-logger-route" -X PATCH \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "plugins": {
      "kafka-logger": {
        "meta_format": "origin"
      }
    }
  }'

Send a request to the Route again to generate a new log entry:

curl -i "http://127.0.0.1:9080/get"

You should see an HTTP/1.1 200 OK response.

You should see a log entry in the Kafka topic similar to the following:

GET /get HTTP/1.1
x-forwarded-proto: http
x-forwarded-host: 127.0.0.1
user-agent: curl/8.7.1
x-forwarded-port: 9080
host: 127.0.0.1:9080
accept: */*

Log Request and Response Headers With Plugin Metadata

The following example demonstrates how to customize the log format using plugin metadata and built-in variables to log specific headers from request and response.

Plugin metadata is used to configure the common metadata fields of all Plugin instances of the same Plugin. It is useful when a Plugin is enabled across multiple resources and requires a universal update to their metadata fields.

First, create a Route with kafka-logger. Set meta_format to default (required for custom log format via plugin metadata) and batch_max_size to 1 to send log entries immediately:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "kafka-logger-route",
    "uri": "/get",
    "plugins": {
      "kafka-logger": {
        "meta_format": "default",
        "brokers": [
          {
            "host": "127.0.0.1",
            "port": 9092
          }
        ],
        "kafka_topic": "test2",
        "key": "key1",
        "batch_max_size": 1
      }
    },
    "upstream": {
      "nodes": {
        "httpbin.org:80": 1
      },
      "type": "roundrobin"
    }
  }'

note

If meta_format is set to origin, log entries will remain in origin format regardless of plugin metadata log format configuration.

Next, configure the Plugin metadata for kafka-logger to log the custom request header env and the response header Content-Type:

curl "http://127.0.0.1:9180/apisix/admin/plugin_metadata/kafka-logger" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "log_format": {
      "host": "$host",
      "@timestamp": "$time_iso8601",
      "client_ip": "$remote_addr",
      "env": "$http_env",
      "resp_content_type": "$sent_http_Content_Type"
    }
  }'

Send a request to the Route with the env header:

curl -i "http://127.0.0.1:9080/get" -H "env: dev"

You should see a log entry in the Kafka topic similar to the following:

{
  "@timestamp": "2023-11-10T23:09:04+00:00",
  "host": "127.0.0.1",
  "client_ip": "127.0.0.1",
  "route_id": "kafka-logger-route",
  "env": "dev",
  "resp_content_type": "application/json"
}

Log Request Bodies Conditionally

The following example demonstrates how to conditionally log request bodies.

Create a Route with kafka-logger. Set include_req_body to true to include the request body, and set include_req_body_expr to only include the body when the URL query string log_body equals yes:

curl "http://127.0.0.1:9180/apisix/admin/routes" -X PUT \
  -H "X-API-KEY: ${admin_key}" \
  -d '{
    "id": "kafka-logger-route",
    "uri": "/post",
    "plugins": {
      "kafka-logger": {
        "brokers": [
          {
            "host": "127.0.0.1",
            "port": 9092
          }
        ],
        "kafka_topic": "test2",
        "key": "key1",
        "batch_max_size": 1,
        "include_req_body": true,
        "include_req_body_expr": [["arg_log_body", "==", "yes"]]
      }
    },
    "upstream": {
      "nodes": {
        "httpbin.org:80": 1
      },
      "type": "roundrobin"
    }
  }'

Send a request to the Route with a URL query string satisfying the condition:

curl -i "http://127.0.0.1:9080/post?log_body=yes" -X POST -d '{"env": "dev"}'

You should see the request body logged:

{
  "...",
  "request": {
    "method": "POST",
    "body": "{\"env\": \"dev\"}",
    "size": 179
  }
}

Send another request without the URL query string:

curl -i "http://127.0.0.1:9080/post" -X POST -d '{"env": "dev"}'

You should not observe the request body in the log.

note

If you have customized the log_format in addition to setting include_req_body or include_resp_body to true, the Plugin will not include the bodies in the logs. As a workaround, you can use the NGINX variable $request_body in the log format:

{
  "kafka-logger": {
    "log_format": {"body": "$request_body"}
  }
}