Amazon Web Services (AWS) Elastic Cloud Compute (EC2) is Amazon’s Cloud virtualization platform. AWS EC2 is used by tens of thousands of companies, including large enterprises, representing millions of instances (virtual servers), according to industry estimates.
AWS EC2 instances do not maintain the names and IP addresses of their virtual servers when they are restarted, resulting in a “missing server” and downtime of end user applications. For example, if an AWS instance (server) running a database restarts, it will be assigned a new private IP address and domain name, which will result in a “connection” error for the servers using it. The impacted servers have no mechanism to automatically discover the new private IP address of the database server.
Because of this, without dnsfly, an administrator would need to first diagnose the problem behind the outage, and then manually update the IP names and addresses each time a server reboots, and for each instance. This could entail hundreds of IP names and addresses and happen daily or even multiple times per day, depending on the configuration. This not only adds a significant amount of time-critical work for IT staff, it also introduces the possibility of errors because of the manual nature of the process.
dnsfly maintains persistent private IP names for all clients within an application infrastructure, creating IP persistence for AWS EC2 users. When an instance restarts, it will update the new IP address on the dnsfly virtual appliance. All instances will query the dnsfly appliance to connect to each other.
More specifically, when an administrator installs dnsfly for the first time, the installation process puts a dnsfly agent on each instance (virtual server). The agents use key pairs to authenticate their connection with the dnsfly appliance. Every time an instance restarts, it will acquire a new IP address and domain name from the AWS DHCP server pools. The dnsfly agent installed on each instance will send the new IP address and domain name to the dnsfly virtual appliance. The dnsfly appliance therefore maintains at all times up to date IP addresses and domain names for each instance automatically, with no manual updating required from an administrator. The network’s Web servers query the dnsfly virtual appliance as needed to retrieve up to date private IP addresses for the instances, allowing end user applications to run seamlessly.
Diagram: dnsfly Approach to Creating IP Persistence for AWS EC2
The above image illustrates on the left-hand side a network infrastructure without a dnsfly appliance, and on the right-hand side how a dsnfly appliance would interact with network elements.