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kafka-logger

Description#

The kafka-logger Plugin is used to push logs as JSON objects to Apache Kafka clusters. It works as a Kafka client driver for the ngx_lua Nginx module.

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#

NameTypeRequiredDefaultValid valuesDescription
broker_listobjectTrueList of Kafka brokers (nodes).
kafka_topicstringTrueTarget topic to push the logs for organisation.
producer_typestringFalseasync["async", "sync"]Message sending mode of the producer.
required_acksintegerFalse1[0, 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. See Apache Kafka documentation for more.
keystringFalseKey used for allocating partitions for messages.
timeoutintegerFalse3[1,...]Timeout for the upstream to send data.
namestringFalse"kafka logger"Unique identifier for the batch processor.
meta_formatenumFalse"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.
include_req_bodybooleanFalsefalse[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_exprarrayFalseFilter 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.
include_resp_bodybooleanFalsefalse[false, true]When set to true includes the response body in the log.
include_resp_body_exprarrayFalseFilter 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.
cluster_nameintegerFalse1[0,...]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_numintegeroptional200[1,...]batch_num parameter in lua-resty-kafka. The merge message and batch is send to the server. Unit is message count.
producer_batch_sizeintegeroptional1048576[0,...]batch_size parameter in lua-resty-kafka in bytes.
producer_max_bufferingintegeroptional50000[1,...]max_buffering parameter in lua-resty-kafka representing maximum buffer size. Unit is message count.
producer_time_lingerintegeroptional1[1,...]flush_time parameter in lua-resty-kafka 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:

NameTypeRequiredDefaultDescription
log_formatobjectFalse{"host": "$host", "@timestamp": "$time_iso8601", "client_ip": "$remote_addr"}Log format declared as key value pairs in JSON format. Values only support strings. APISIX or Nginx variables can be used by prefixing the string with $.
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.

The example below shows how you can configure through the Admin API:

curl http://127.0.0.1:9180/apisix/admin/plugin_metadata/kafka-logger -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"log_format": {
"host": "$host",
"@timestamp": "$time_iso8601",
"client_ip": "$remote_addr"
}
}'

With this configuration, your logs would be formatted as shown below:

{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","route_id":"1"}
{"host":"localhost","@timestamp":"2020-09-23T19:05:05-04:00","client_ip":"127.0.0.1","route_id":"1"}

Enabling the Plugin#

The example below shows how you can enable the kafka-logger Plugin on a specific Route:

curl http://127.0.0.1:9180/apisix/admin/routes/5 -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"plugins": {
"kafka-logger": {
"broker_list" :
{
"127.0.0.1":9092
},
"kafka_topic" : "test2",
"key" : "key1",
"batch_max_size": 1,
"name": "kafka logger"
}
},
"upstream": {
"nodes": {
"127.0.0.1:1980": 1
},
"type": "roundrobin"
},
"uri": "/hello"
}'

This Plugin also supports pushing to more than one broker at a time. You can specify multiple brokers in the Plugin configuration as shown below:

"broker_list" :
{
"127.0.0.1":9092,
"127.0.0.1":9093
},

Example usage#

Now, if you make a request to APISIX, it will be logged in your Kafka server:

curl -i http://127.0.0.1:9080/hello

Disable Plugin#

To disable the kafka-logger Plugin, you can delete the corresponding JSON configuration from the Plugin configuration. APISIX will automatically reload and you do not have to restart for this to take effect.

curl http://127.0.0.1:9180/apisix/admin/routes/1  -H 'X-API-KEY: edd1c9f034335f136f87ad84b625c8f1' -X PUT -d '
{
"methods": ["GET"],
"uri": "/hello",
"plugins": {},
"upstream": {
"type": "roundrobin",
"nodes": {
"127.0.0.1:1980": 1
}
}
}'