Instead of only filling __meta_consul_dc when datacenter is set in
consul_sd_config this change fills the label based on what the agent
reports it's current data center is, if datacenter isn't manually set,
otherwise it uses whatever datacenter was set to.
Include position of same SD mechanisms within the same scrape configuration.
Move unique prefixing out of SD implementations and target manager into
its own interface.
In setups where the ServiceAddress is the relevant address for
scraping, users can relabel the `__address__` label to ServiceAddress
+ ":" + ServicePort.
This needs to be documented, of course. Will do once this is LGTM'd.
This reverts commit 0ac7e7217e28dd165787b80219f6085c8d97f814.
See discussion on https://github.com/prometheus/prometheus/pull/812 for
reasoning. While fixing one use case, it breaks others, and we need a
more generic way of handling this.
This change is conceptually very simple, although the diff is large. It
switches logging from "github.com/golang/glog" to
"github.com/prometheus/log", while not actually changing any log
messages. V(1)-style logging has been changed to be log.Debug*().
