[[logstash]]
=== Using Logstash with Shield

IMPORTANT: Shield 2.0+ is compatible with Logstash 2.0 and above.

Logstash provides Elasticsearch https://www.elastic.co/guide/en/logstash/current/plugins-outputs-elasticsearch.html[output], https://www.elastic.co/guide/en/logstash/current/plugins-inputs-elasticsearch.html[input] and https://www.elastic.co/guide/en/logstash/current/plugins-filters-elasticsearch.html[filter] plugins
used to index and retrieve documents through HTTP, transport or client node protocols.
All plugins support authentication and encryption over HTTP, while the output plugin additionally supports these
features over the transport protocol.

NOTE: When using the `elasticsearch` output, only the `transport` and `http` protocol are supported (i.e. `node` protocol is unsupported)

[float]
[[ls-user]]
==== Creating a user

By default, the Shield plugin installs a dedicated user <<roles,role>> that enables the creation of indices with names
that match the `logstash-*` regular expression, along with privileges to read, scroll, index, update, and delete 
documents on those indices:

[source,yaml]
--------------------------------------------------------------------------------------------
logstash:
  cluster: indices:admin/template/get, indices:admin/template/put
  indices:
    'logstash-*': indices:data/write/bulk, indices:data/write/delete, indices:data/write/update, indices:data/read/search, indices:data/read/scroll, create_index
--------------------------------------------------------------------------------------------

See the <<defining-roles,_Role Definition File_>> section for information on modifying roles.

Create a user associated with the `logstash` role on the Elasticsearch cluster, using the <<esusers,`esusers` tool>>:

[source,shell]
--------------------------------------------------
esusers useradd <username> -p <password> -r logstash
--------------------------------------------------

NOTE: When using the transport protocol, the logstash user requires the predefined `transport_client` role in addition to the `logstash` role shown above (`-r logstash,transport_client`).

Once you've created the user, you are ready to configure Logstash.

[float]
[[ls-http]]
==== Connecting with HTTP/HTTPS

Logstash communicates with the Elasticsearch cluster through the REST APIs over HTTP.

[float]
[[ls-http-auth]]
===== Authentication for HTTP protocol

HTTP protocol supports both basic auth and client-certificate authentication through the use of Public Key Infrastructure (PKI).

[float]
[[ls-http-auth-basic]]
===== Basic Authentication

The  input, filter, and output plugins all support HTTP Basic Authentication. To use basic authentication when connecting to an instance of Elasticsearch with Shield, you configure the plugins to include username and password credentials with each request. For example, the following snippet configures credentials for the output plugin. The credentials are configured the same way for each plugin type.

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch {
    protocol => "http"
    ...
    user => ... # string
    password => ... # string
  }
}
--------------------------------------------------

[float]
[[ls-http-auth-pki]]
===== PKI Authentication

Elasticsearch Output supports the use of X.509 client-certificate to authenticate Logstash requests. To enable this you need to set up the following configuration parameters:

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch {
    ...
    keystore => ... # string
    keystore_password => ... # string
  }
}
--------------------------------------------------

[float]
[[ls-http-ssl]]
===== SSL/TLS Configuration for HTTPS

To enable SSL/TLS encryption for HTTPS, use the following configuration block:

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch {
    ...
    ssl => true
    cacert => '/path/to/cert.pem' <1>
  }
}
--------------------------------------------------
<1> The path to the `.pem` file in your filesystem that contains the Certificate Authority's certificate.

[float]
[[ls-transport]]
==== Connecting with Transport protocol

When using the `elasticsearch_java` plugins in Logstash, you can set the `protocol` option to `transport`. With `transport`, Logstash communicates with the Elasticsearch cluster through the same
protocol nodes use between each other.

In order to unlock this option, it's necessary to install an additional plugin in Logstash using the following command:

[source, shell]
--------------------------------------------------
bin/plugin install logstash-output-elasticsearch_java_shield
--------------------------------------------------

[float]
[[ls-transport-auth]]
===== Authentication for Transport protocol

Transport protocol supports both basic auth and client-certificate authentication through the use of Public Key Infrastructure (PKI).

[float]
[[ls-transport-auth-basic]]
===== Basic Authentication

To connect to an instance of Elasticsearch with Shield using basic auth, set up the username and password credentials with the following configuration parameters:

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch_java {
    protocol => "transport"
    ...
    user => ... # string
    password => ... # string
  }
}
--------------------------------------------------

[float]
[[ls-transport-auth-pki]]
===== PKI Authentication

To connect to an instance of Elasticsearch with Shield using client-certificate authentication you need to setup the keystore path which contain the client's certificate and the keystore password in the configuration:

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch_java {
    protocol => "transport"    
    ...
    ssl => true
    keystore => ... # string
    keystore_password => ... # string
  }
}
--------------------------------------------------

[float]
[[ls-transport-conf]]
===== SSL Configuration for Transport protocols

Specify the paths to the keystore and truststore `.jks` files with the following configuration parameters:

[source, shell]
--------------------------------------------------
input { ... }
output {
  elasticsearch_java {
    protocol => "transport"
    host => ... # string (optional)
    cluster => ... # string (optional)
    ...
    ssl => true
    keystore =>  ... # string
    keystore_password =>  ... # string
    truststore =>  ... # string
    truststore_password =>  ... # string
  }
}
--------------------------------------------------

For more information on encryption and certificates, see the <<ssl-tls,Securing Nodes>> section:

[float]
[[ls-failure]]
==== Failures

Logstash raises an exception that halts the processing pipeline when the server's certificate does not validate over SSL 
on any of the protocols discussed in this section. Same for the invalid user credentials.
