+ bind :8400
+ default_backend random
+ use_backend %[req.hdr(X-Shard),map(/usr/local/etc/haproxy/sharding.map)]
+
+backend random
+ server b1 backend-1:8080 check
+ server b2 backend-2:8080 check
+ server b3 backend-3:8080 check
+
+backend backend_1
+ server b1 backend-1:8080 check
+
+backend backend_2
+ server b2 backend-2:8080 check
+
+backend backend_3
+ server b3 backend-3:8080 check