When Elasticsearch fails or is in a unhealthy state, the ES status indicator appears red due to red indices containing unassigned shards. You can recover it automatically or manually.
The automatic option will allow watchdog to delete all the red indices and reset Elasticsearch. The manual option will provide you with two sub-options. You can reallocate the unassigned shards to the master node or another available node or delete all the red indices.
When the Elasticsearch returns to its healthy state, the status indicator appears green.