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Showing posts from 2017

Common HTTP Load Balancing Methods

Estimating utilization of the application servers may not be always possible. In many companies, while average cpu utilization of any server is changing between %20 and %30, they may become hardly respond to incoming requests at peak times. When an unexpected over-utilization occurs, the first method that comes to mind is provisioning new instances (of course your company is using a virtualization or cloud architecture) to the application server pool.
Sometimes it may not be the solution for over-utilization. As the number of app servers increases it becomes important that the requests are distributed equally across these servers. Becoming some of the servers unresponsive may have a devastating effect on the environment.

Traditionally, load balancers are used to distribute incoming traffic across multiple app instances. Load balancing provides some benefits like scaling the application farm, supporting heavy network traffic, detecting unhealthy app instances and automatically removin…

Iptables Rules For 2 Node Elasticsearch Cluster

Below shell script is useful for securing two node elasticsearch cluster. To apply suitable iptables rules, just run it on each of the ES Nodes.

With this script rules are applied for: Allowing traffic on loopback adapters. Allowing ES Nodes to communicate each other. Allowing incoming ssh connections. Allowing incoming icmp (ping) requests. Allowing outgoing DNS requests. Allowing Access to Elasticsearch HTTP Interface. Dropping all other traffic.