Consul: query by arbitrary number of tags

[elecnix]

The consul namer currently allows specifying one tag to filter services, through the includeTag configuration key. That tag appears in the name like this:

/#/<prefix>/<datacenter>/<tag>/<serviceName>

The consul API supports searching with more than one tag.

That could be expressed by moving the tag to the tail of the path, interpreting as tags any residual fragments after the service name:

/#/<prefix>/<datacenter>/<serviceName>/<tag1>/<tag2>

One use-case is for resolving a service to a "preferred" service set, but also by service version. Two tag sets would be used; for example: primary and secondary, v1 & v2. That allows routing a v2 request preferably to a primary but only if it supports v2.