How to check if ElasticSearch is running

By default elastic search runs on port 9200.

$ curl http://localhost:9200
{
  "ok" : true,
  "status" : 200,
  "name" : "White Pilgrim",
  "version" : {
    "number" : "0.90.13",
    "build_hash" : "249c9c5e06765c9e929e92b1d235e1ba4dc679fa",
    "build_timestamp" : "2014-03-25T15:27:12Z",
    "build_snapshot" : false,
    "lucene_version" : "4.6"
  },
  "tagline" : "You Know, for Search"
}

1. gem install rest-client

require 'rest-client'
RestClient.get('http://localhost:9200')


$ irb
> require 'rest-client'
 => true
> x = RestClient.get('http://localhost:9200')
 => "{\n  \"ok\" : true,\n  \"status\" : 200,\n  \"name\" : \"White Pilgrim\",\n  \"version\" : {\n    \"number\" : \"0.90.13\",\n    \"build_hash\" : \"249c9c5e06765c9e929e92b1d235e1ba4dc679fa\",\n    \"build_timestamp\" : \"2014-03-25T15:27:12Z\",\n    \"build_snapshot\" : false,\n    \"lucene_version\" : \"4.6\"\n  },\n  \"tagline\" : \"You Know, for Search\"\n}\n"
> x['ok']
 => "ok"
> JSON.parse(x)
 => {"ok"=>true, "status"=>200, "name"=>"White Pilgrim", "version"=>{"number"=>"0.90.13", "build_hash"=>"249c9c5e06765c9e929e92b1d235e1ba4dc679fa", "build_timestamp"=>"2014-03-25T15:27:12Z", "build_snapshot"=>false, "lucene_version"=>"4.6"}, "tagline"=>"You Know, for Search"}