Troubleshooting Elastic Search

I'm following this tutorial:

Instead of a server for filebeat I'm using an Ubuntu 16.x workstation.

Everything looks OK, but the out of:
curl -XGET 'http://localhost:9200/filebeat-*/_search?pretty'

is

{
"took" : 1,
"timed_out" : false,
"_shards" : {
"total" : 0,
"successful" : 0,
"failed" : 0
},
"hits" : {
"total" : 0,
"max_score" : 0.0,
"hits" : [ ]
}
}

The tutorial says this means there is a configuration error. Where's a good place to start troubleshooting?