Service Configuration

Each service can register one or more URL prefixes for which it serves traffic. A URL prefix is a host/path combination without a scheme since SSL has already been terminated and all traffic is expected to be HTTP. To register a URL prefix add a tag urlprefix-host/path to the service definition.

By default, traffic is distributed evenly across all service instances which register a URL prefix but you can set the amount of traffic a set of instances will receive ("Canary testing"). See [Traffic Shaping](#Traffic Shaping) below.

A background process watches for service definition and health status changes in consul. When a change is detected a new routing table is constructed using the commands described in [Config Commands](#Config Commands).

Consul and the ${DC} Variable

Consul allows to discover services by two different names:

• mysvc.service.consul
• mysvc.service.dc1.consul

Assuming that dc1 is the datacenter of the local agent during service discovery the first name may return instances from a different datacenter whereas the second name will only return instances from dc1.

If you have multiple environments with separate consul servers and distinguish them via datacenter then you can use ${DC} in the urlprefix- tag to simplify the registration.

This way you can always register your service with the same set of tags urlprefix-mysvc.service.consul,urlprefix-mysvc.service.${DC}.consul without knowing the consul configuration.