kafka.go

// Copyright (c) 2014 Ashley Jeffs
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package input

import (
	"github.com/Jeffail/benthos/lib/input/reader"
	"github.com/Jeffail/benthos/lib/log"
	"github.com/Jeffail/benthos/lib/metrics"
	"github.com/Jeffail/benthos/lib/types"
	"github.com/Jeffail/benthos/lib/util/tls"
)

//------------------------------------------------------------------------------

func init() {
	Constructors[TypeKafka] = TypeSpec{
		constructor: NewKafka,
		description: `
Connects to a kafka (0.8+) server. Offsets are managed within kafka as per the
consumer group (set via config). Only one partition per input is supported, if
you wish to balance partitions across a consumer group look at the
` + "`kafka_balanced`" + ` input type instead.

The field ` + "`max_batch_count`" + ` specifies the maximum number of prefetched
messages to be batched together. When more than one message is batched they can
be split into individual messages with the ` + "`split`" + ` processor.

The target version by default will be the oldest supported, as it is expected
that the server will be backwards compatible. In order to support newer client
features you should increase this version up to the known version of the target
server.

` + tls.Documentation + `

### Metadata

This input adds the following metadata fields to each message:

` + "```" + `
- kafka_key
- kafka_topic
- kafka_partition
- kafka_offset
- kafka_timestamp_unix
- All existing message headers (version 0.11+)
` + "```" + `

You can access these metadata fields using
[function interpolation](../config_interpolation.md#metadata).`,
	}
}

//------------------------------------------------------------------------------

// NewKafka creates a new Kafka input type.
func NewKafka(conf Config, mgr types.Manager, log log.Modular, stats metrics.Type) (Type, error) {
	k, err := reader.NewKafka(conf.Kafka, log, stats)
	if err != nil {
		return nil, err
	}
	return NewReader("kafka", reader.NewPreserver(k), log, stats)
}

//------------------------------------------------------------------------------