// NewEnvironObserver waits for the state to have a valid environment
// configuration and returns a new environment observer. While waiting
// for the first environment configuration, it will return with
// tomb.ErrDying if it receives a value on dying.
func NewEnvironObserver(st *state.State) (*EnvironObserver, error) {
config, err := st.EnvironConfig()
if err != nil {
return nil, err
}
environ, err := environs.New(config)
if err != nil {
return nil, fmt.Errorf("cannot make Environ: %v", err)
}
environWatcher := st.WatchForEnvironConfigChanges()
obs := &EnvironObserver{
st: st,
environ: environ,
environWatcher: environWatcher,
}
go func() {
defer obs.tomb.Done()
defer watcher.Stop(environWatcher, &obs.tomb)
obs.tomb.Kill(obs.loop())
}()
return obs, nil
}