Read from OpenSearch

As we ship Logstash events to an OpenSearch cluster using the OpenSearch output plugin, we can also perform read operations on an OpenSearch cluster and load data into Logstash using the OpenSearch input plugin.

The OpenSearch input plugin reads the search query results performed on an OpenSearch cluster and loads them into Logstash. This lets you replay test logs, reindex, and perform other operations based on the loaded data. You can schedule ingestions to run periodically by using cron expressions, or manually load data into Logstash by running the query once.

OpenSearch input plugin

To run the OpenSearch input plugin, add the configuration to the pipeline.conf file within your Logstash’s config folder. The example below runs the match_all query filter and loads in data once.

input {
  opensearch {
    hosts       => "https://hostname:port"
    user        => "admin"
    password    => "admin"
    index       => "logstash-logs-%{+YYYY.MM.dd}"
    query       => '{ "query": { "match_all": {}} }'
  }
}

filter {
}

output {
}

To ingest data according to a schedule, use a cron expression that specifies the schedule you want. For example, to load in data every minute, add schedule => "* * * * *" to the input section of your pipeline.conf file.

Like the output plugin, after adding your configuration to the pipeline.conf file, start Logstash by providing the path to this file:

 $ bin/logstash -f config/pipeline.conf --config.reload.automatic

config/pipeline.conf is a relative path to the pipeline.conf file. You can use an absolute path as well.

Adding stdout{} to the output{} section of your pipeline.conf file prints the query results to the console.

To reindex the data into an OpenSearch domain, add the destination domain configuration in the output{} section like shown here.