BINGO!!
[2017-02-28T10:19:24,022][INFO ][logstash.outputs.elasticsearch] Running health check to see if an Elasticsearch connection is working {:healthcheck_url=>http://10.1.1.89:9200/, :path=>"/"}
[2017-02-28T10:19:24,029][WARN ][logstash.outputs.elasticsearch] Restored connection to ES instance {:url=>#<URI::HTTP:0x1a2e77f7 URL:http://10.1.1.89:9200/>}
You MUST add the following config lines to your /etc/logstash/logstash.yml
xpack.monitoring.enabled: true
xpack.monitoring.elasticsearch.url: http://X.X.X.X:9200
Where X.X.X.X is the IP of your Elastic cluster.
EDIT: Clarity