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Latest commit 83f978f Mar 21, 2017 @pitr pitr bump to 1.9.3

Fluent::Plugin::Elasticsearch, a plugin for Fluentd

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Send your logs to ElasticSearch (and search them with Kibana maybe?)

Note: For Amazon Elasticsearch Service please consider using fluent-plugin-aws-elasticsearch-service


$ gem install fluent-plugin-elasticsearch


In your Fluentd configuration, use @type elasticsearch. Additional configuration is optional, default values would look like this:

<match my.logs>
  @type elasticsearch
  host localhost
  port 9200
  index_name fluentd
  type_name fluentd

Index templates

This plugin creates ElasticSearch indices by merely writing to them. Consider using Index Templates to gain control of what get indexed and how. See this example for a good starting point.



hosts host1:port1,host2:port2,host3:port3
# or

You can specify multiple ElasticSearch hosts with separator ",".

If you specify multiple hosts, this plugin will load balance updates to ElasticSearch. This is an elasticsearch-ruby feature, the default strategy is round-robin.

user, password, path, scheme, ssl_verify

If you specify this option, host and port options are ignored.

user demo
password secret
path /elastic_search/
scheme https

You can specify user and password for HTTP basic auth. If used in conjunction with a hosts list, then these options will be used by default i.e. if you do not provide any of these options within the hosts listed.

Specify ssl_verify false to skip ssl verification (defaults to true)


logstash_format true # defaults to false

This is meant to make writing data into ElasticSearch indices compatible to what Logstash calls them. By doing this, one could take advantage of Kibana. See logstash_prefix and logstash_dateformat to customize this index name pattern. The index name will be #{logstash_prefix}-#{formated_date}


logstash_prefix mylogs # defaults to "logstash"


The strftime format to generate index target index name when logstash_format is set to true. By default, the records are inserted into index logstash-YYYY.MM.DD. This option, alongwith logstash_prefix lets us insert into specified index like mylogs-YYYYMM for a monthly index.

logstash_dateformat %Y.%m. # defaults to "%Y.%m.%d"


The format of the time stamp field (@timestamp or what you specify with time_key). This parameter only has an effect when logstash_format is true as it only affects the name of the index we write to. Please see Time#strftime for information about the value of this format.

Setting this to a known format can vastly improve your log ingestion speed if all most of your logs are in the same format. If there is an error parsing this format the timestamp will default to the ingestion time. If you are on Ruby 2.0 or later you can get a further performance improvment by installing the "strptime" gem: fluent-gem install strptime.

For example to parse ISO8601 times with sub-second precision:

time_key_format %Y-%m-%dT%H:%M:%S.%N%z


By default, when inserting records in Logstash format, @timestamp is dynamically created with the time at log ingestion. If you'd like to use a custom time, include an @timestamp with your record.


You can specify an option time_key (like the option described in tail Input Plugin) to replace @timestamp key.

Suppose you have settings

logstash_format true
time_key vtm

Your input is:

  "title": "developer",
  "vtm": "2014-12-19T08:01:03Z"

The output will be

  "title": "developer",
  "@timestamp": "2014-12-19T08:01:03Z",
  "vtm": "2014-12-19T08:01:03Z"

See time_key_exclude_timestamp to avoid adding @timestamp.


time_key_exclude_timestamp false

By default, setting time_key will copy the value to an additional field @timestamp. When setting time_key_exclude_timestamp true, no additional field will be added.


utc_index true

By default, the records inserted into index logstash-YYMMDD with UTC (Coordinated Universal Time). This option allows to use local time if you describe utc_index to false.


Tell this plugin to find the index name to write to in the record under this key in preference to other mechanisms. Key can be specified as path to nested record using dot ('.') as a separator.

If it is present in the record (and the value is non falsey) the value will be used as the index name to write to and then removed from the record before output; if it is not found then it will use logstash_format or index_name settings as configured.

Suppose you have the following settings

target_index_key @target_index
index_name fallback

If your input is:

  "title": "developer",
  "@timestamp": "2014-12-19T08:01:03Z",
  "@target_index": "logstash-2014.12.19"

The output would be

  "title": "developer",
  "@timestamp": "2014-12-19T08:01:03Z",

and this record will be written to the specified index (logstash-2014.12.19) rather than fallback.


Similar to target_index_key config, find the type name to write to in the record under this key (or nested record). If key not found in record - fallback to type_name (default "fluentd").


The name of the template to define. If a template by the name given is already present, it will be left unchanged.

This parameter along with template_file allow the plugin to behave similarly to Logstash (it installs a template at creation time) so that raw records are available. See

template_file must also be specified.


The path to the file containing the template to install.

template_name must also be specified.


Specify index templates in form of hash. Can contain multiple templates.

templates { "templane_name_1": "path_to_template_1_file", "templane_name_2": "path_to_template_2_file"}

If template_file and template_name are set, then this parameter will be ignored.


You can specify HTTP request timeout.

This is useful when ElasticSearch cannot return response for bulk request within the default of 5 seconds.

request_timeout 15s # defaults to 5s


You can tune how the elasticsearch-transport host reloading feature works. By default it will reload the host list from the server every 10,000th request to spread the load. This can be an issue if your ElasticSearch cluster is behind a Reverse Proxy, as Fluentd process may not have direct network access to the ElasticSearch nodes.

reload_connections false # defaults to true


Indicates that the elasticsearch-transport will try to reload the nodes addresses if there is a failure while making the request, this can be useful to quickly remove a dead node from the list of addresses.

reload_on_failure true # defaults to false


You can set in the elasticsearch-transport how often dead connections from the elasticsearch-transport's pool will be resurrected.

resurrect_after 5 # defaults to 60s

include_tag_key, tag_key

include_tag_key true # defaults to false
tag_key tag # defaults to tag

This will add the Fluentd tag in the JSON record. For instance, if you have a config like this:

<match my.logs>
  @type elasticsearch
  include_tag_key true
  tag_key _key

The record inserted into ElasticSearch would be

{"_key":"my.logs", "name":"Johnny Doeie"}


id_key request_id # use "request_id" field as a record id in ES

By default, all records inserted into ElasticSearch get a random _id. This option allows to use a field in the record as an identifier.

This following record {"name":"Johnny","request_id":"87d89af7daffad6"} will trigger the following ElasticSearch command

{ "index" : { "_index" : "logstash-2013.01.01, "_type" : "fluentd", "_id" : "87d89af7daffad6" } }
{ "name": "Johnny", "request_id": "87d89af7daffad6" }


parent_key a_parent # use "a_parent" field value to set _parent in elasticsearch command

If your input is

{ "name": "Johnny", "a_parent": "my_parent" }

ElasticSearch command would be

{ "index" : { "_index" : "****", "_type" : "****", "_id" : "****", "_parent" : "my_parent" } }
{ "name": "Johnny", "a_parent": "my_parent" }

if parent_key is not configed or the parent_key is absent in input record, nothing will happen.


Similar to parent_key config, will add _routing into elasticsearch command if routing_key is set and the field does exist in input event.


parent_key a_parent
routing_key a_routing
remove_keys a_parent, a_routing # a_parent and a_routing fields won't be sent to elasticsearch


Remove keys on update will not update the configured keys in elasticsearch when a record is being updated.
This setting only has any effect if the write operation is update or upsert.

If the write setting is upsert then these keys are only removed if the record is being updated, if the record does not exist (by id) then all of the keys are indexed.

remove_keys_on_update foo,bar


This setting allows remove_keys_on_update to be configured with a key in each record, in much the same way as target_index_key works. The configured key is removed before indexing in elasticsearch. If both remove_keys_on_update and remove_keys_on_update_key is present in the record then the keys in record are used, if the remove_keys_on_update_key is not present then the value of remove_keys_on_update is used as a fallback.

remove_keys_on_update_key keys_to_skip


The write_operation can be any of:

Operation Description
index (default) new data is added while existing data (based on its id) is replaced (reindexed).
create adds new data - if the data already exists (based on its id), the op is skipped.
update updates existing data (based on its id). If no data is found, the op is skipped.
upsert known as merge or insert if the data does not exist, updates if the data exists (based on its id).

Please note, id is required in create, update, and upsert scenario. Without id, the message will be dropped.


With logstash_format true, elasticsearch plugin parses timestamp field for generating index name. If the record has invalid timestamp value, this plugin emits an error event to @ERROR label with time_parse_error_tag configured tag.

Default value is Fluent::ElasticsearchOutput::TimeParser.error for backward compatibility. :: separated tag is not good for tag routing because some plugins assume tag is separated by .. We recommend to set this parameter like time_parse_error_tag es_plugin.output.time.error. We will change default value to . separated tag.


Indicates that the plugin should reset connection on any error (reconnect on next send). By default it will reconnect only on "host unreachable exceptions". We recommended to set this true in the presence of elasticsearch shield.

reconnect_on_error true # defaults to false

Client/host certificate options

Need to verify ElasticSearch's certificate? You can use the following parameter to specify a CA instead of using an environment variable.

ca_file /path/to/your/ca/cert

Does your ElasticSearch cluster want to verify client connections? You can specify the following parameters to use your client certificate, key, and key password for your connection.

client_cert /path/to/your/client/cert
client_key /path/to/your/private/key
client_key_pass password

Proxy Support

Starting with version 0.8.0, this gem uses excon, which supports proxy with environment variables -

Buffered output options

fluentd-plugin-elasticsearch extends Fluentd's builtin Buffered Output plugin. It adds the following options:

buffer_type memory
flush_interval 60
retry_limit 17
retry_wait 1.0
num_threads 1

The value for option buffer_chunk_limit should not exceed value http.max_content_length in your Elasticsearch setup (by default it is 100mb).

Hash flattening

Elasticsearch will complain if you send object and concrete values to the same field. For example, you might have logs that look this, from different places:

{"people" => 100} {"people" => {"some" => "thing"}}

The second log line will be rejected by the Elasticsearch parser because objects and concrete values can't live in the same field. To combat this, you can enable hash flattening.

flatten_hashes true
flatten_hashes_separator _

This will produce elasticsearch output that looks like this: {"people_some" => "thing"}

Note that the flattener does not deal with arrays at this time.

Not seeing a config you need?

We try to keep the scope of this plugin small and not add too many configuration options. If you think an option would be useful to others, feel free to open an issue or contribute a Pull Request.

Alternatively, consider using fluent-plugin-forest. For example, to configure multiple tags to be sent to different ElasticSearch indices:

<match my.logs.*>
  @type forest
  subtype elasticsearch
  remove_prefix my.logs
    logstash_prefix ${tag}
    # ...

And yet another option is described in Dynamic Configuration section.

Dynamic configuration

If you want configurations to depend on information in messages, you can use elasticsearch_dynamic. This is an experimental variation of the ElasticSearch plugin allows configuration values to be specified in ways such as the below:

<match my.logs.*>
  @type elasticsearch_dynamic
  hosts ${record['host1']}:9200,${record['host2']}:9200
  index_name my_index.${}
  logstash_prefix ${tag_parts[3]}
  port ${9200+rand(4)}
  index_name ${tag_parts[2]}-${}

Please note, this uses Ruby's eval for every message, so there are performance and security implications.


If you have a question, open an Issue.


There are usually a few feature requests, tagged Easy, Normal and Hard. Feel free to work on any one of them.

Pull Requests are welcomed.

Pull Request Graph

Running tests

Install dev dependencies:

$ gem install bundler
$ bundle install
$ bundle exec rake test