golang/dep is a prototype dependency management tool. Soon to be an official versioning tool. Current status Alpha.
Get the tool via
$ go get -u github.com/golang/dep/...
Typical usage on a new repo might be
$ dep init $ dep ensure -update
To update a dependency to a new version, you might run
$ dep ensure github.com/pkg/errors@^0.8.0
Note that the manifest and lock file formats have now been finalized. These will remain compatible even as the tool changes.