Client-side load-balancing with Apache HTTP Client

Question

We are building a scalable point-to-point microservice architecture with client-side load-balancing and fail-over. The base idea is to manage service discovery with DNS SRV records, just as HashiCorps' Consul does.

As HTTP client we use Apache http-components.

The algorithm I envision looks something like this:

• On start-up the client looks up the SRV records for the service it wants to consume.
• The client configures an instance of HttpClient to round-robin through the available services.
• The client periodically queries the DNS server for updates (governed by the DNS record's TTL) and updates the HttpClient if hosts are added or removed.
• Code that invokes the client only uses absolute paths without scheme, host or port.

Constraints:

• Respect priority and weight fields of SRV records.
• Implement fail-over with a back-off strategy and temporary host disabling.

Is there a pretty way to configure Apache's http-components this way that I haven't found yet? Is there any better library for this kind of requirements?

Thanks a lot for input and ideas.

Answer 1

I found Ribbon by Netflix which does exactly what I need.