You can change the cipher suites used by HAProxy and specify whether to encrypt in-flight data transferred between internal endpoints.
All public API endpoints in a VMware Integrated OpenStack deployment can be accessed using TLS 1.1 or 1.2. For HA deployments, traffic between internal endpoints is encrypted using TLS 1.2 only. Because the internal endpoints in a compact or tiny deployment are located on a single virtual machine, traffic between internal endpoints is not encrypted for those deployment types by default.
When internal in-flight encryption is enabled, HAProxy acts as a Layer 4 load balancer instead of a Layer 7 load balancer for internal API calls and Horizon traffic. To ensure strong encryption performance, the Apache HTTP server on each controller terminates TLS for each individual OpenStack service. The Apache server then forwards the request over a local loopback service to the back-end service, such as Nova, Neutron, or Cinder. HAProxy also re-encrypts the request when sending it to a back-end controller node over the internal network.