Create ServerErrCh to surface server errors back to caller.

manager/runner.go

@@ -23,7 +23,7 @@ import (
 	"github.com/hashicorp/consul-template/template"
 	"github.com/hashicorp/consul-template/watch"
 
-	multierror "github.com/hashicorp/go-multierror"
+	"github.com/hashicorp/go-multierror"
 )
 
 const (
@@ -38,6 +38,10 @@ type Runner struct {
 	ErrCh  chan error
 	DoneCh chan struct{}
 
+	// ServerErrCh is a channel to surface error responses from the server up the calling stack
+	// and will only hold a maximum of one error at a time
+	ServerErrCh chan error
+
 	// config is the Config that created this Runner. It is used internally to
 	// construct other objects and pass data.
 	config *config.Config
@@ -199,6 +203,7 @@ func NewRunner(config *config.Config, dry bool) (*Runner, error) {
 	runner := &Runner{
 		ErrCh:         make(chan error),
 		DoneCh:        make(chan struct{}),
+		ServerErrCh:   make(chan error, 1),
 		config:        config,
 		dry:           dry,
 		inStream:      os.Stdin,
@@ -434,7 +439,17 @@ func (r *Runner) Start() {
 			log.Printf("[ERR] (runner) watcher reported error: %s", err)
 			r.ErrCh <- err
 			return
-
+		case err := <-r.watcher.ServerErrCh():
+			// If we got a server error we push the error up the stack
+			log.Printf("[ERR] (runner) sending server error back to caller")
+			// Drain the error channel if anything already exists
+			select {
+			case <-r.ServerErrCh:
+				continue
+			default:
+			}
+			r.ServerErrCh <- err
+			goto OUTER
 		case err := <-r.vaultTokenWatcher.ErrCh():
 			// Push the error back up the stack
 			log.Printf("[ERR] (runner): %s", err)

watch/view.go

@@ -121,7 +121,7 @@ func (v *View) DataAndLastIndex() (interface{}, uint64) {
 // accounts for interrupts on the interrupt channel. This allows the poll
 // function to be fired in a goroutine, but then halted even if the fetch
 // function is in the middle of a blocking query.
-func (v *View) poll(viewCh chan<- *View, errCh chan<- error) {
+func (v *View) poll(viewCh chan<- *View, errCh chan<- error, serverErrCh chan<- error) {
 	var retries int
 
 	for {
@@ -162,6 +162,7 @@ func (v *View) poll(viewCh chan<- *View, errCh chan<- error) {
 		case err := <-fetchErrCh:
 			if !errors.Is(err, errLookup) && v.retryFunc != nil {
 				retry, sleep := v.retryFunc(retries)
+				serverErrCh <- err
 				if retry {
 					log.Printf("[WARN] (view) %s (retry attempt %d after %q)",
 						err, retries+1, sleep)

watch/view_test.go

@@ -20,8 +20,9 @@ func TestPoll_returnsViewCh(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	defer view.stop()
 
 	select {
@@ -44,18 +45,26 @@ func TestPoll_returnsErrCh(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	defer view.stop()
 
 	select {
 	case data := <-viewCh:
 		t.Errorf("expected no data, but got %+v", data)
 	case err := <-errCh:
 		expected := "failed to contact server"
+		select {
+		case <-serverErrCh:
+			t.Errorf("sent server error, expected lookup error")
+		default:
+
+		}
 		if err.Error() != expected {
 			t.Errorf("expected %q to be %q", err.Error(), expected)
 		}
+
 	case <-view.stopCh:
 		t.Errorf("poll received premature stop")
 	}
@@ -71,15 +80,18 @@ func TestPoll_stopsViewStopCh(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	view.stop()
 
 	select {
 	case <-viewCh:
 		t.Errorf("expected no data, but received view data")
 	case err := <-errCh:
 		t.Errorf("error while polling: %s", err)
+	case err := <-serverErrCh:
+		t.Errorf("server error while polling : %s", err)
 	case <-time.After(20 * time.Millisecond):
 		// No data was received, test passes
 	}
@@ -95,8 +107,9 @@ func TestPoll_once(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	defer view.stop()
 
 	select {
@@ -113,6 +126,8 @@ func TestPoll_once(t *testing.T) {
 		t.Errorf("expected no data (should have stopped), but received view data")
 	case err := <-errCh:
 		t.Errorf("error while polling: %s", err)
+	case err := <-serverErrCh:
+		t.Errorf("server error while polling: %s", err)
 	case <-view.stopCh:
 		t.Errorf("poll received premature stop")
 	case <-time.After(20 * time.Millisecond):
@@ -133,8 +148,9 @@ func TestPoll_retries(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	defer view.stop()
 
 	select {
@@ -143,6 +159,9 @@ func TestPoll_retries(t *testing.T) {
 	case <-time.After(100 * time.Millisecond):
 	}
 
+	// need to receive error to avoid timeout
+	<-serverErrCh
+
 	select {
 	case <-viewCh:
 		// Got this far, so the test passes
@@ -291,15 +310,18 @@ func TestStop_stopsPolling(t *testing.T) {
 
 	viewCh := make(chan *View)
 	errCh := make(chan error)
+	serverErrCh := make(chan error)
 
-	go view.poll(viewCh, errCh)
+	go view.poll(viewCh, errCh, serverErrCh)
 	view.stop()
 
 	select {
 	case v := <-viewCh:
 		t.Errorf("got unexpected view: %#v", v)
 	case err := <-errCh:
 		t.Error(err)
+	case err := <-serverErrCh:
+		t.Error(err)
 	case <-view.stopCh:
 		// Successfully stopped
 	}

watch/watcher.go

@@ -30,6 +30,9 @@ type Watcher struct {
 	// errCh is the chan where any errors will be published.
 	errCh chan error
 
+	// serverErrCh is the chan where response errors from the server will be published
+	serverErrCh chan error
+
 	// blockQueryWaitTime is amount of time in seconds to do a blocking query for
 	blockQueryWaitTime time.Duration
 
@@ -95,6 +98,7 @@ func NewWatcher(i *NewWatcherInput) *Watcher {
 		depViewMap:         make(map[string]*View),
 		dataCh:             make(chan *View, dataBufferSize),
 		errCh:              make(chan error),
+		serverErrCh:        make(chan error),
 		maxStale:           i.MaxStale,
 		once:               i.Once,
 		blockQueryWaitTime: i.BlockQueryWaitTime,
@@ -121,6 +125,15 @@ func (w *Watcher) ErrCh() <-chan error {
 	return w.errCh
 }
 
+// ServerErrCh returns a read-only channel of errors returned by the server
+// as a response to each consul-template instance
+func (w *Watcher) ServerErrCh() <-chan error {
+	if w == nil {
+		return nil
+	}
+	return w.serverErrCh
+}
+
 // Add adds the given dependency to the list of monitored dependencies
 // and start the associated view. If the dependency already exists, no action is
 // taken.
@@ -169,7 +182,7 @@ func (w *Watcher) Add(d dep.Dependency) (bool, error) {
 	log.Printf("[TRACE] (watcher) %s starting", d)
 
 	w.depViewMap[d.String()] = v
-	go v.poll(w.dataCh, w.errCh)
+	go v.poll(w.dataCh, w.errCh, w.serverErrCh)
 
 	return true, nil
 }