You can configure a logstash output to send events to a logstash input is in another pipeline that is running in a different process or on a different host.

To do so, you should first configure the downstream pipeline with a logstash input plugin, bound to an available port so that it can listen for inbound connections. Security is enabled by default, so you will need to either provide identity material or disable SSL.

input {
  logstash {
    port => 8080
    # SSL IDENTITY 
    ssl_keystore_path      => "/path/to/identity.p12"
    ssl_keystore_password  => "${SSL_IDENTITY_PASSWORD}"
  }
}

Once the downstream pipeline is configured and running, you may send events from any number of upstream pipelines by adding a logstash output plugin that points to the downstream input. You may need to configure SSL to trust the certificates presented by the downstream input plugin.

output {
  logstash {
    host => "10.0.0.123"
    port => 8080
    # SSL TRUST 
    ssl_truststore_path => "/path/to/truststore.p12"
    ssl_truststore_password => "${SSL_TRUST_PASSWORD}"
  }
}