start refactoring a bit. create a separate package for public ip getter with tests.

Author: dan-v

pkg/server/publicip/publicip.go

@@ -0,0 +1,12 @@
+package publicip
+
+import "errors"
+
+type Client interface {
+	GetIP() (string, error)
+	ProviderURL() string
+}
+
+var (
+	ErrInvalidIPAddress = errors.New("invalid ip address")
+)