Fluentd
0.12
0.12
  • Introduction
  • Overview
    • Getting Started
    • Installation
    • Life of a Fluentd event
    • Support
    • FAQ
  • Use Cases
    • Centralized App Logging
    • Monitoring Service Logs
    • Data Analytics
    • Connecting to Data Storages
    • Stream Processing
    • Windows Event Collection
    • IoT Data Logger
  • Configuration
    • Config File Syntax
    • Routing Examples
    • Recipes
  • Deployment
    • Logging
    • Monitoring
    • Signals
    • RPC
    • High Availability Config
    • Failure Scenarios
    • Performance Tuning
    • Plugin Management
    • Trouble Shooting
    • Secure Forwarding
    • Fluentd UI
    • Command Line Option
  • Container Deployment
    • Docker Image
    • Docker Logging Driver
    • Docker Compose
    • Kubernetes
  • Input Plugins
    • tail
    • forward
    • secure_forward
    • udp
    • tcp
    • http
    • unix
    • syslog
    • exec
    • scribe
    • multiprocess
    • dummy
    • Others
  • Output Plugins
    • file
    • s3
    • kafka
    • forward
    • secure_forward
    • exec
    • exec_filter
    • copy
    • geoip
    • roundrobin
    • stdout
    • null
    • webhdfs
    • splunk
    • mongo
    • mongo_replset
    • relabel
    • rewrite_tag_filter
    • Others
  • Buffer Plugins
    • memory
    • file
  • Filter Plugins
    • record_transformer
    • grep
    • parser
    • stdout
  • Parser Plugins
    • regexp
    • apache2
    • apache_error
    • nginx
    • syslog
    • ltsv
    • csv
    • tsv
    • json
    • multiline
    • none
  • Formatter Plugins
    • out_file
    • json
    • ltsv
    • csv
    • msgpack
    • hash
    • single_value
  • Developer
    • Plugin Development
    • Community
    • Mailing List
    • Source Code
    • Bug Tracking
    • ChangeLog
    • Logo
  • Articles
    • Store Apache Logs into MongoDB
    • Apache To Riak
    • Store Apache Logs into Amazon S3
    • Before Install
    • Cep Norikra
    • Collect Glusterfs Logs
    • Common Log Formats
    • Docker Logging Efk Compose
    • Docker Logging
    • Filter Modify Apache
    • Forwarding Over Ssl
    • Free Alternative To Splunk By Fluentd
    • Data Collection to Hadoop (HDFS)
    • Data Analytics with Treasure Data
    • Install By Chef
    • Install By Deb
    • Install By Dmg
    • Install By Gem
    • Install By Rpm
    • Install From Source
    • Install On Beanstalk
    • Install On Heroku
    • Java
    • Kinesis Stream
    • Kubernetes Fluentd
    • Monitoring by Prometheus
    • Monitoring by Rest Api
    • Nodejs
    • Performance Tuning Multi Process
    • Performance Tuning Single Process
    • Perl
    • Php
    • Python
    • Quickstart
    • Raspberrypi Cloud Data Logger
    • Recipe Apache Logs To Elasticsearch
    • Recipe Apache Logs To Mongo
    • Recipe Apache Logs To S3
    • Recipe Apache Logs To Treasure Data
    • Recipe Cloudstack To Mongodb
    • Recipe Csv To Elasticsearch
    • Recipe Csv To Mongo
    • Recipe Csv To S3
    • Recipe Csv To Treasure Data
    • Recipe Http Rest Api To Elasticsearch
    • Recipe Http Rest Api To Mongo
    • Recipe Http Rest Api To S3
    • Recipe Http Rest Api To Treasure Data
    • Recipe Json To Elasticsearch
    • Recipe Json To Mongo
    • Recipe Json To S3
    • Recipe Json To Treasure Data
    • Recipe Nginx To Elasticsearch
    • Recipe Nginx To Mongo
    • Recipe Nginx To S3
    • Recipe Nginx To Treasure Data
    • Recipe Syslog To Elasticsearch
    • Recipe Syslog To Mongo
    • Recipe Syslog To S3
    • Recipe Syslog To Treasure Data
    • Recipe Tsv To Elasticsearch
    • Recipe Tsv To Mongo
    • Recipe Tsv To S3
    • Recipe Tsv To Treasure Data
    • Ruby
    • Scala
    • Splunk Like Grep And Alert Email
Powered by GitBook
On this page
  • Example Configuration
  • Parameters
  • type (required)
  • <server> (at least one is required)
  • require_ack_response
  • ack_response_timeout
  • <secondary> (optional)
  • send_timeout
  • recover_wait
  • heartbeat_type
  • heartbeat_interval
  • phi_failure_detector
  • phi_threshold
  • hard_timeout
  • standby
  • expire_dns_cache
  • dns_round_robin
  • Buffered Output Parameters
  • buffer_type
  • buffer_queue_limit, buffer_chunk_limit
  • flush_interval
  • flush_at_shutdown
  • retry_wait, max_retry_wait
  • retry_limit, disable_retry_limit
  • num_threads
  • slow_flush_log_threshold
  • Troubleshooting
  • "no nodes are available"

Was this helpful?

  1. Output Plugins

forward

PreviouskafkaNextsecure_forward

Last updated 5 years ago

Was this helpful?

The out_forward Buffered Output plugin forwards events to other fluentd nodes. This plugin supports load-balancing and automatic fail-over (a.k.a. active-active backup). For replication, please use the plugin.

The out_forward plugin detects server faults using a "φ accrual failure detector" algorithm. You can customize the parameters of the algorithm. When a server fault recovers, the plugin makes the server available automatically after a few seconds.

The out_forward plugin supports at-most-once and at-least-once semantics. The default is at-most-once. Do NOT use this plugin for inter-DC or public internet data transfer without secure connections. All the data is not encrypted, and this plugin is not designed for high-latency network environment. If you require a secure connection between nodes, please consider using .

Example Configuration

out_forward is included in Fluentd's core. No additional installation process is required.

<match pattern>
  @type forward
  send_timeout 60s
  recover_wait 10s
  hard_timeout 60s

  <server>
    name myserver1
    host 192.168.1.3
    port 24224
    weight 60
  </server>
  <server>
    name myserver2
    host 192.168.1.4
    port 24224
    weight 60
  </server>
  ...

  <secondary>
    @type file
    path /var/log/fluent/forward-failed
  </secondary>
</match>

Parameters

type (required)

The value must be forward.

<server> (at least one is required)

The destination servers. Each server must have following information.

  • name: The name of the server. This parameter is used in error

    messages.

  • host (required): The IP address or host name of the server.

  • port: The port number of the host. The default is 24224. Note

    that both TCP packets (event stream) and UDP packets (heartbeat

    message) are sent to this port.

  • weight: The load balancing weight. If the weight of one server is

    20 and the weight of the other server is 30, events are sent in a

    2:3 ratio. The default weight is 60.

  • standby: Set the destination to standby node. The default is

    false. standby servers will be selected when all non-standby

    servers went down.

require_ack_response

Change the protocol to at-least-once. The plugin waits the ack from destination's in_forward plugin.

ack_response_timeout

This option is used when require_ack_response is true. The default is 190. This default value is based on popular tcp_syn_retries.

If set 0, this plugin doesn't wait the ack response.

<secondary> (optional)

The backup destination that is used when all servers are unavailable.

send_timeout

The timeout time when sending event logs. The default is 60 seconds.

recover_wait

The wait time before accepting a server fault recovery. The default is 10 seconds.

heartbeat_type

The transport protocol to use for heartbeats. The default is "udp", but you can select "tcp" as well. Set "none" to disable heartbeat.

heartbeat_interval

The interval of the heartbeat packer. The default is 1 second.

phi_failure_detector

Use the "Phi accrual failure detector" to detect server failure. The default value is true.

phi_threshold

The threshold parameter used to detect server faults. The default value is 16.

`phi_threshold` is deeply related to `heartbeat_interval`. If you are using longer `heartbeat_interval`, please use the larger `phi_threshold`. Otherwise you will see frequent detachments of destination servers. The default value 16 is tuned for `heartbeat_interval` 1s.

hard_timeout

The hard timeout used to detect server failure. The default value is equal to the send_timeout parameter.

standby

Marks a node as the standby node for an Active-Standby model between Fluentd nodes. When an active node goes down, the standby node is promoted to an active node. The standby node is not used by the out_forward plugin until then.

<match pattern>
  @type forward
  ...

  <server>
    name myserver1
    host 192.168.1.3
    weight 60
  </server>
  <server>  # forward doesn't use myserver2 until myserver1 goes down
    name myserver2
    host 192.168.1.4
    weight 60
    standby
  </server>
  ...
</match>

expire_dns_cache

Set TTL to expire DNS cache in seconds. Set 0 not to use DNS Cache. The default is nil (which means the persistent cache).

dns_round_robin

Enable client-side DNS round robin. Uniform randomly pick an IP address to send data when a hostname has serveral IP addresses.

`heartbeat_type udp` is not available with `dns_round_robin true`. Use `heartbeat_type tcp` or `heartbeat_type none`.

Buffered Output Parameters

For advanced usage, you can tune Fluentd's internal buffering mechanism with these parameters.

buffer_type

buffer_queue_limit, buffer_chunk_limit

flush_interval

The interval between data flushes. The default is 60s. The suffixes "s" (seconds), "m" (minutes), and "h" (hours) can be used.

flush_at_shutdown

If set to true, Fluentd waits for the buffer to flush at shutdown. By default, it is set to true for Memory Buffer and false for File Buffer.

retry_wait, max_retry_wait

The initial and maximum intervals between write retries. The default values are 1.0 seconds and unset (no limit). The interval doubles (with +/-12.5% randomness) every retry until max_retry_wait is reached.

Since td-agent will retry 17 times before giving up by default (see the retry_limit parameter for details), the sleep interval can be up to approximately 131072 seconds (roughly 36 hours) in the default configurations.

retry_limit, disable_retry_limit

The limit on the number of retries before buffered data is discarded, and an option to disable that limit (if true, the value of retry_limit is ignored and there is no limit). The default values are 17 and false (not disabled). If the limit is reached, buffered data is discarded and the retry interval is reset to its initial value (retry_wait).

num_threads

The number of threads to flush the buffer. This option can be used to parallelize writes into the output(s) designated by the output plugin. Increasing the number of threads improves the flush throughput to hide write / network latency. The default is 1.

slow_flush_log_threshold

The threshold for checking chunk flush performance. The default value is 20.0 seconds. Note that parameter type is float, not time.

If chunk flush takes longer time than this threshold, fluentd logs warning message like below:

2016-12-19 12:00:00 +0000 [warn]: buffer flush took longer time than slow_flush_log_threshold: elapsed_time = 15.0031226690043695 slow_flush_log_threshold=10.0 plugin_id="foo"

log_level option

The log_level option allows the user to set different levels of logging for each plugin. The supported log levels are: fatal, error, warn, info, debug, and trace.

Troubleshooting

"no nodes are available"

Please make sure that you can communicate with port 24224 using not only TCP, but also UDP. These commands will be useful for checking the network configuration.

$ telnet host 24224
$ nmap -p 24224 -sU host

Please see the article for the basic structure and syntax of the configuration file.

The buffer type is memory by default () for the ease of testing, however file () buffer type is always recommended for the production deployments. If you use file buffer type, buffer_path parameter is required.

The length of the chunk queue and the size of each chunk, respectively. Please see the article for the basic buffer structure. The default values are 64 and 8m, respectively. The suffixes "k" (KB), "m" (MB), and "g" (GB) can be used for buffer_chunk_limit.

Please see the for further details.

Please note that there is one where VMware will occasionally lose small UDP packets used for heartbeat.

If this article is incorrect or outdated, or omits critical information, please . is a open source project under . All components are available under the Apache 2 License.

Config File
buf_memory
buf_file
Buffer Plugin Overview
logging article
known issue
let us know
Fluentd
Cloud Native Computing Foundation (CNCF)
out_copy
in_secure_forward