todo list

[grimmer0125]

if (this.socket) {  <- may need to add this. 
      this.socket.close
}

2. [done]
   if redis is not connected, it will be nil and make panic in the following code

3. [done] local elasticsearch server for dev, using docker

4. update the go elasticsearch lib to be compatible with elasticsearch to v6 (if we use v6 of elasticsearch server, go server will throw error, e.g. not acceptable data)

5. instead of elasticsearch of aws, use google app/compute engine OR apply free open source project plan of algolia (20KB record size, better than free basic plan). But they need to setup ACL part (only read from web, write from server)

ref: https://www.algolia.com/pricing, https://www.algolia.com/for-open-source