FAQ

Why Not Use a Proxy?

Although proxies like Nginx or HAProxy can solve the issue of IP propagation, they also introduce a layer of complexity. For a service such as PostgreSQL, drivers expect only one node to contact, which makes a proxy a single point of failure and removes most of the advantages of high availability. Another idea is to deploy multiple proxies within a hot-standby setup, which adds even more complexity, as an IaaS specific failover needs to be implemented.

Why Not Use Static IP Addresses?

Although it sounds tempting to use the IP addresses of Service Instances in service bindings, there is one major downside to that. Depending on the IaaS, it might not be possible to resurrect VMs with static IP addresses if the compute node containing it is currently down. The a9s Data Services Framework (a9s DSF) aims to support all network types. This includes dynamic networks in which crashed VMs get new IP addresses when they are restarted. In such a case it would be necessary to recreate all service bindings.