How to access Elasticsearch Cluster in VPN with Spring Boot

Question

I have an Elasticsearch cluster in a VPN.

How can my Spring Boot application access the cluster securely if it is located on a separate server outside of the VPN and how can I configure it in the Spring boot configuration (application.yml/application.properties)?

I also want the application to connect to the cluster i an way so that if i have eg 2 Master eligible nodes and one fails, the connection remains intact.

Answer 1

1. if you have only 2 master eligble nodes, you are at risk of the "split brain problem". there is a easy formula for the calculation of the required number of master nodes:

   M = 2F +1 ( m=master node count, f=number of master nodes possible to fail at same time)

2. in your application define all master nodes as target for the elasticsearch client. The client will handle the failover. see elasticsearc client documentation or https://qbox.io/blog/rest-calls-made-easy-part-2-sniffing-elasticsearch for a example

3. the vpn should not be handled by your application. the infrastructure (server, firewall) is the right place to address it. try to develop your application environment agnostic. this will make your app easier to develop, maintain and make it more robust to infrastructure changes