Head plugin is used to check the status of the cluster (servers/indices/ shards). Are they up and running? But this is not supported in elasticsearch 5.x. Are there alternatives to serve the same purpose?
The latest Kibana comes with X-Pack monitoring as standard.
If you don't use Kibana...
ElasticHQ is an open source application that offers a simplified interface for managing and monitoring Elasticsearch clusters.
http://www.elastichq.org/
There is also a Chrome browser Extansion of Elasticsearch Head.
There are probably more out there 
thanks
Yes there's more:
Cerebro: https://github.com/lmenezes/cerebro
with docker image:
https://github.com/yannart/docker-cerebro
And lots of tutorial if you search for "cerebro elasticsearch".
I was also using head but quickly move to kopf and now I'm using cerebro.