// WatchForEnvironConfigChanges returns a NotifyWatcher that observes
// changes to the environment configuration.
// Note that although the NotifyWatchResult contains an Error field,
// it's not used because we are only returning a single watcher,
// so we use the regular error return.
func (e *EnvironWatcher) WatchForEnvironConfigChanges() (params.NotifyWatchResult, error) {
result := params.NotifyWatchResult{}
canWatch, err := e.getCanWatch()
if err != nil {
return result, err
}
// TODO(dimitern) If we have multiple environments in state, use a
// tag argument here and as a method argument.
if !canWatch("") {
return result, ErrPerm
}
watch := e.st.WatchForEnvironConfigChanges()
// Consume the initial event. Technically, API
// calls to Watch 'transmit' the initial event
// in the Watch response. But NotifyWatchers
// have no state to transmit.
if _, ok := <-watch.Changes(); ok {
result.NotifyWatcherId = e.resources.Register(watch)
} else {
return result, watcher.MustErr(watch)
}
return result, nil
}
// WatchMachineErrorRetry returns a NotifyWatcher that notifies when
// the provisioner should retry provisioning machines with transient errors.
func (p *ProvisionerAPI) WatchMachineErrorRetry() (params.NotifyWatchResult, error) {
result := params.NotifyWatchResult{}
canWatch, err := p.getCanWatchMachines()
if err != nil {
return params.NotifyWatchResult{}, err
}
if !canWatch("") {
return result, common.ErrPerm
}
watch := newWatchMachineErrorRetry()
// Consume any initial event and forward it to the result.
if _, ok := <-watch.Changes(); ok {
result.NotifyWatcherId = p.resources.Register(watch)
} else {
return result, watcher.MustErr(watch)
}
return result, nil
}