FTP

This page describes the usage of the Stream Reactor FTP Source Connector.

Provide the remote directories and on specified intervals, the list of files in the directories is refreshed. Files are downloaded when they were not known before, or when their timestamp or size are changed. Only files with a timestamp younger than the specified maximum age are considered. Hashes of the files are maintained and used to check for content changes. Changed files are then fed into Kafka, either as a whole (update) or only the appended part (tail), depending on the configuration. Optionally, file bodies can be transformed through a pluggable system prior to putting them into Kafka.

Connector Class

io.lenses.streamreactor.connect.ftp.source.FtpSourceConnector

Example

For more examples see the tutorials.

name=ftp-source
connector.class=io.lenses.streamreactor.connect.ftp.source.FtpSourceConnector
tasks.max=1

#server settings
connect.ftp.address=localhost:21
connect.ftp.user=ftp
connect.ftp.password=ftp

#refresh rate, every minute
connect.ftp.refresh=PT1M

#ignore files older than 14 days.
connect.ftp.file.maxage=P14D

#monitor /forecasts/weather/ and /logs/ for appends to files.
#any updates go to the topics `weather` and `error-logs` respectively.
connect.ftp.monitor.tail=/forecasts/weather/:weather,/logs/:error-logs

#keep an eye on /statuses/, files are retrieved as a whole and sent to topic `status`
connect.ftp.monitor.update=/statuses/:status

#keystyle controls the format of the key and can be string or struct.
#string only provides the file name
#struct provides a structure with the filename and offset
connect.ftp.keystyle=struct

Data types

Each Kafka record represents a file and has the following types.

• The format of the keys is configurable through connect.ftp.keystyle=string|struct. It can be a string with the file name, or a FileInfo structure with the name: string and offset: long. The offset is always 0 for files that are updated as a whole, and hence only relevant for tailed files.

• The values of the records contain the body of the file as bytes.

Tailing Versus Update as a Whole

The following rules are used.

Tailed files are only allowed to grow. Bytes that have been appended to it since the last inspection are yielded. Preceding bytes are not allowed to change;

Updated files can grow, shrink and change anywhere. The entire contents are yielded.

Data converters

Instead of dumping whole file bodies (and the danger of exceeding Kafka’s message.max.bytes), one might want to give an interpretation to the data contained in the files before putting it into Kafka. For example, if the files that are fetched from the FTP are comma-separated values (CSVs), one might prefer to have a stream of CSV records instead. To allow to do so, the connector provides a pluggable conversion of SourceRecords. Right before sending a SourceRecord to the Connect framework, it is run through an object that implements:

package io.lenses.streamreactor.connect.ftp

trait SourceRecordConverter extends Configurable {
    def convert(in:SourceRecord) : java.util.List[SourceRecord]
}

The default object that is used is a pass-through converter, an instance of:

class NopSourceRecordConverter extends SourceRecordConverter{
    override def configure(props: util.Map[String, _]): Unit = {}
    override def convert(in: SourceRecord): util.List[SourceRecord] = Seq(in).asJava
}

To override it, create your own implementation of SourceRecordConverter and place the jar in the plugin.path.

connect.ftp.sourcerecordconverter=your.name.space.YourConverter

To learn more examples of using the FTP Kafka connector read this blog.

Option Reference

Name	Description	Type	Default Value
connect.ftp.address	host[:port] of the ftp server	string
connect.ftp.user	Username to connect with	string
connect.ftp.password	Password to connect with	string
connect.ftp.refresh	iso8601 duration that the server is polled	string
connect.ftp.file.maxage	iso8601 duration for how old files can be	string
connect.ftp.keystyle	SourceRecord keystyle, string or struct	string
connect.ftp.protocol	Protocol to use, FTP or FTPS	string	ftp
connect.ftp.timeout	Ftp connection timeout in milliseconds	int	30000
connect.ftp.filter	Regular expression to use when selecting files for processing	string	.*
connect.ftp.monitor.tail	Comma separated lists of path:destinationtopic; tail of file to tracked	string
connect.ftp.monitor.update	Comma separated lists of path:destinationtopic; whole file is tracked	string
connect.ftp.monitor.slicesize	File slice size in bytes	int	-1
connect.ftp.fileconverter	File converter class	string	io.lenses.streamreactor.connect.ftp.source.SimpleFileConverter
connect.ftp.sourcerecordconverter	Source record converter class	string	io.lenses.streamreactor.connect.ftp.source.NopSourceRecordConverter
connect.ftp.max.poll.records	Max number of records returned per poll	int	10000