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Webhdfs output plugin

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Webhdfs output plugin

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Plugin version: v3.1.0
Released on: 2023-10-03
Changelog

For other versions, see the Versioned plugin docs.

Getting Help

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For questions about the plugin, open a topic in the Discuss forums. For bugs or feature requests, open an issue in Github. For the list of Elastic supported plugins, please consult the Elastic Support Matrix.

Description

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This plugin sends Logstash events into files in HDFS via the webhdfs REST API.

Dependencies

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This plugin has no dependency on jars from hadoop, thus reducing configuration and compatibility problems. It uses the webhdfs gem from Kazuki Ohta and TAGOMORI Satoshi (@see: https://github.com/kzk/webhdfs). Optional dependencies are zlib and snappy gem if you use the compression functionality.

Operational Notes

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If you get an error like:

Max write retries reached. Exception: initialize: name or service not known {:level=>:error}

make sure that the hostname of your namenode is resolvable on the host running Logstash. When creating/appending to a file, webhdfs somtime sends a 307 TEMPORARY_REDIRECT with the HOSTNAME of the machine its running on.

Usage

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This is an example of Logstash config:

input {
  ...
}
filter {
  ...
}
output {
  webhdfs {
    host => "127.0.0.1"                 # (required)
    port => 50070                       # (optional, default: 50070)
    path => "/user/logstash/dt=%{+YYYY-MM-dd}/logstash-%{+HH}.log"  # (required)
    user => "hue"                       # (required)
  }
}

Webhdfs Output Configuration Options

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This plugin supports the following configuration options plus the Common Options described later.

Setting	Input type	Required
`compression`	string, one of `["none", "snappy", "gzip"]`	No
`flush_size`	number	No
`host`	string	Yes
`idle_flush_time`	number	No
`kerberos_keytab`	string	No
`open_timeout`	number	No
`path`	string	Yes
`port`	number	No
`read_timeout`	number	No
`retry_interval`	number	No
`retry_known_errors`	boolean	No
`retry_times`	number	No
`single_file_per_thread`	boolean	No
`snappy_bufsize`	number	No
`snappy_format`	string, one of `["stream", "file"]`	No
`ssl_cert`	string	No
`ssl_key`	string	No
`standby_host`	string	No
`standby_port`	number	No
`use_httpfs`	boolean	No
`use_kerberos_auth`	boolean	No
`use_ssl_auth`	boolean	No
`user`	string	Yes

Also see Common Options for a list of options supported by all output plugins.

`compression`

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Value can be any of: none, snappy, gzip
Default value is "none"

Compress output. One of [none, snappy, gzip]

`flush_size`

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Value type is number
Default value is 500

Sending data to webhdfs if event count is above, even if store_interval_in_secs is not reached.

`host`

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This is a required setting.
Value type is string
There is no default value for this setting.

The server name for webhdfs/httpfs connections.

`idle_flush_time`

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Value type is number
Default value is 1

Sending data to webhdfs in x seconds intervals.

`kerberos_keytab`

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Value type is string
There is no default value for this setting.

Set kerberos keytab file. Note that the gssapi library needs to be available to use this.

`open_timeout`

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Value type is number
Default value is 30

WebHdfs open timeout, default 30s.

`path`

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This is a required setting.
Value type is string
There is no default value for this setting.

The path to the file to write to. Event fields can be used here, as well as date fields in the joda time format, e.g.: /user/logstash/dt=%{+YYYY-MM-dd}/%{@source_host}-%{+HH}.log

`port`

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Value type is number
Default value is 50070

The server port for webhdfs/httpfs connections.

`read_timeout`

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Value type is number
Default value is 30

The WebHdfs read timeout, default 30s.

`retry_interval`

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Value type is number
Default value is 0.5

How long should we wait between retries.

`retry_known_errors`

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Value type is boolean
Default value is true

Retry some known webhdfs errors. These may be caused by race conditions when appending to same file, etc.

`retry_times`

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Value type is number
Default value is 5

How many times should we retry. If retry_times is exceeded, an error will be logged and the event will be discarded.

`single_file_per_thread`

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Value type is boolean
Default value is false

Avoid appending to same file in multiple threads. This solves some problems with multiple logstash output threads and locked file leases in webhdfs. If this option is set to true, %{[@metadata][thread_id]} needs to be used in path config settting.

`snappy_bufsize`

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Value type is number
Default value is 32768

Set snappy chunksize. Only neccessary for stream format. Defaults to 32k. Max is 65536 @see http://code.google.com/p/snappy/source/browse/trunk/framing_format.txt

`snappy_format`

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Value can be any of: stream, file
Default value is "stream"

Set snappy format. One of "stream", "file". Set to stream to be hive compatible.

`ssl_cert`

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Value type is string
There is no default value for this setting.

Set ssl cert file.

`ssl_key`

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Value type is string
There is no default value for this setting.

Set ssl key file.

`standby_host`

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Value type is string
Default value is false

Standby namenode for ha hdfs.

`standby_port`

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Value type is number
Default value is 50070

Standby namenode port for ha hdfs.

`use_httpfs`

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Value type is boolean
Default value is false

Use httpfs mode if set to true, else webhdfs.

`use_kerberos_auth`

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Value type is boolean
Default value is false

Set kerberos authentication.

`use_ssl_auth`

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Value type is boolean
Default value is false

Set ssl authentication. Note that the openssl library needs to be available to use this.

`user`

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This is a required setting.
Value type is string
There is no default value for this setting.

The Username for webhdfs.

Common Options

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The following configuration options are supported by all output plugins:

Setting	Input type	Required
`codec`	codec	No
`enable_metric`	boolean	No
`id`	string	No

`codec`

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Value type is codec
Default value is "line"

The codec used for output data. Output codecs are a convenient method for encoding your data before it leaves the output without needing a separate filter in your Logstash pipeline.

`enable_metric`

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Value type is boolean
Default value is true

Disable or enable metric logging for this specific plugin instance. By default we record all the metrics we can, but you can disable metrics collection for a specific plugin.

`id`

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Value type is string
There is no default value for this setting.

Add a unique ID to the plugin configuration. If no ID is specified, Logstash will generate one. It is strongly recommended to set this ID in your configuration. This is particularly useful when you have two or more plugins of the same type. For example, if you have 2 webhdfs outputs. Adding a named ID in this case will help in monitoring Logstash when using the monitoring APIs.

output {
  webhdfs {
    id => "my_plugin_id"
  }
}

Variable substitution in the id field only supports environment variables and does not support the use of values from the secret store.

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