From https://wiki.mozilla.org/Security/Server_Side_TLS
update the three cipher suites:
  # Modern cipher suite (no legacy browser support) - not currently used
  # Intermediate cipher suite (default) - currently used
  # Old cipher suite (maximum compatibility but insecure) - not currently used

The user can select from among 3 predefined cipher lists: modern,
intermediate, or old. Alternatively the use may  provide a custom
cipher list see "man 1 ciphers". The list is used to negotiate a
cipher between a user and haproxyi during bind.

The predefined lists are from:
https://wiki.mozilla.org/Security/Server_Side_TLS

A new option to "oc adm router", --ciphers, is added to specify
the cipher list. The values are modern|intermediate|old, or a
":" separated list of ciphers from "man 1 ciphers"

Option --ciphers creates an environmen variable, ROUTER_CIPHERS,
which is passed to the router pod.

See https://trello.com/c/oeP7vrTZ