Provide function for finding address of interface used in outgoing connections

[embs]

I'm working on instrumenting go services so they may make Zipkin aware of their location and found (through this SO answer) this way for fetching service IP.

I saw there's already a function for getting address given an interface:

common/network/interface.go

Line 9 in 955c130

func GetFirstAddressOf(name string) (string, error) {

I guess services will almost (?) always make use of eth0 interface but it seems to me that getting the address without fixing it for a given interface is a more robust way of finding service IP.

If so, shall we provide this, for instance, GetOutboundIP function in weaveworks/commons?