Elasticsearch

Installation and testing

The first thing you want to do for local development is install ElasticSearch in your machine and test it to see if it is running. It requires Java to be installed. The installation is pretty straightforward:

Mac OS X: brew install elasticsearch
Ubuntu: sudo apt-get install elasticsearch

Then start it:

Mac OS X: brew services start elasticsearch
Ubuntu: sudo service elasticsearch start

For testing it, the easiest way is with curl. It might take a few seconds for it to start, so don’t panic if you don’t get any response at first.

curl localhost:9200

Example response:

{
  "name" : "Hydro-Man",
  "cluster_name" : "elasticsearch_gkbonetti",
  "version" : {
    "number" : "2.3.5",
    "build_hash" : "90f439ff60a3c0f497f91663701e64ccd01edbb4",
    "build_timestamp" : "2016-07-27T10:36:52Z",
    "build_snapshot" : false,
    "lucene_version" : "5.5.0"
  },
  "tagline" : "You Know, for Search"
}

Setting up tools for development

When you are getting started with ElasticSearch (ES) it might be good to have a graphical tool that helps you explore your data. A plugin called elasticsearch-head does just that. To install it, do the following:

Find out in which folder ES is installed: ls -l $(which elasticsearch)
cd into this folder and run the plugin installation binary: elasticsearch/bin/plugin -install mobz/elasticsearch-head
Open https://localhost:9200/_plugin/head/ in your browser

If everything worked as expected you should be seeing a nice GUI where you can explore your data.

Introduction

ElasticSearch has a well-documented JSON API, but you’ll probably want to use some libraries that handle that for you:

Elasticsearch - the official low level wrapper for the HTTP API
Elasticsearch-rails - the official high level Rails integration that helps you to connect your Rails models with ElasticSearch using either ActiveRecord or Repository pattern
Chewy - An alternative, non-official high level Rails integration that is very popular and arguably has better documentation

Let’s use the first option for testing the connection:

gem install elasticsearch

Then fire up the ruby terminal and try it out:

require 'elasticsearch'

client = Elasticsearch::Client.new log: true
# by default it connects to https://localhost:9200

client.transport.reload_connections!
client.cluster.health

client.search q: 'test'

Searchkick

If you want to setup quickly elasticsearch you can use the searchkick gem :

gem 'searchkick'

Add searchkick to models you want to search.

class Product < ActiveRecord::Base
  searchkick
end

Add data to the search index.

Product.reindex

And to query, use:

products = Product.search "apples"
products.each do |product|
  puts product.name
end

Pretty quick, elasticsearch knowledge not required ;-)

More information here : https://github.com/ankane/searchkick