fix(tiller): fix spurious "no release found" errors.

There are some places where releases are only located if they are in the
state DEPLOYED. That particular logic was incorrectly used for upgrades.
That caused #1566. While fixing that issue, I found that this was also
the root cause of #1587 (though because it was off by one). I added a
generic method to get the last release, regardless of its status.

This allows some behaviors that previously failed:

- 'helm upgrade' can now be performed on a DELETED release
- 'helm rollback' can now be performed on a DELETED release even if
  there is only one revision of that release history.

Closes #1566
Closes #1587

pkg/storage/storage.go

@@ -139,6 +139,19 @@ func (s *Storage) History(name string) ([]*rspb.Release, error) {
 	return l, nil
 }
 
+func (s *Storage) Last(name string) (*rspb.Release, error) {
+	h, err := s.History(name)
+	if err != nil {
+		return nil, err
+	}
+	if len(h) == 0 {
+		return nil, fmt.Errorf("no revision for release %q", name)
+	}
+
+	relutil.Reverse(h, relutil.SortByRevision)
+	return h[0], nil
+}
+
 // makeKey concatenates a release name and version into
 // a string with format ```<release_name>#v<version>```.
 // This key is used to uniquely identify storage objects.

pkg/storage/storage_test.go

@@ -217,6 +217,38 @@ func TestStorageHistory(t *testing.T) {
 	}
 }
 
+func TestStorageLast(t *testing.T) {
+	storage := Init(driver.NewMemory())
+
+	const name = "angry-bird"
+
+	// setup storage with test releases
+	setup := func() {
+		// release records
+		rls0 := ReleaseTestData{Name: name, Version: 1, Status: rspb.Status_SUPERSEDED}.ToRelease()
+		rls1 := ReleaseTestData{Name: name, Version: 2, Status: rspb.Status_SUPERSEDED}.ToRelease()
+		rls2 := ReleaseTestData{Name: name, Version: 3, Status: rspb.Status_SUPERSEDED}.ToRelease()
+		rls3 := ReleaseTestData{Name: name, Version: 4, Status: rspb.Status_FAILED}.ToRelease()
+
+		// create the release records in the storage
+		assertErrNil(t.Fatal, storage.Create(rls0), "Storing release 'angry-bird' (v1)")
+		assertErrNil(t.Fatal, storage.Create(rls1), "Storing release 'angry-bird' (v2)")
+		assertErrNil(t.Fatal, storage.Create(rls2), "Storing release 'angry-bird' (v3)")
+		assertErrNil(t.Fatal, storage.Create(rls3), "Storing release 'angry-bird' (v4)")
+	}
+
+	setup()
+
+	h, err := storage.Last(name)
+	if err != nil {
+		t.Fatalf("Failed to query for release history (%q): %s\n", name, err)
+	}
+
+	if h.Version != 4 {
+		t.Errorf("Expected revision 4, got %d", h.Version)
+	}
+}
+
 type ReleaseTestData struct {
 	Name      string
 	Version   int32

pkg/tiller/release_server.go

@@ -229,17 +229,11 @@ func (s *ReleaseServer) GetReleaseStatus(c ctx.Context, req *services.GetRelease
 	var rel *release.Release
 
 	if req.Version <= 0 {
-		h, err := s.env.Releases.History(req.Name)
+		var err error
+		rel, err = s.env.Releases.Last(req.Name)
 		if err != nil {
-			return nil, fmt.Errorf("getting deployed release '%s': %s", req.Name, err)
-		}
-		if len(h) < 1 {
-			return nil, errMissingRelease
+			return nil, fmt.Errorf("getting deployed release %q: %s", req.Name, err)
 		}
-
-		relutil.Reverse(h, relutil.SortByRevision)
-		rel = h[0]
-
 	} else {
 		var err error
 		if rel, err = s.env.Releases.Get(req.Name, req.Version); err != nil {
@@ -376,7 +370,7 @@ func (s *ReleaseServer) prepareUpdate(req *services.UpdateReleaseRequest) (*rele
 	}
 
 	// finds the non-deleted release with the given name
-	currentRelease, err := s.env.Releases.Deployed(req.Name)
+	currentRelease, err := s.env.Releases.Last(req.Name)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -504,17 +498,10 @@ func (s *ReleaseServer) prepareRollback(req *services.RollbackReleaseRequest) (*
 		return nil, nil, errInvalidRevision
 	}
 
-	// finds the non-deleted release with the given name
-	h, err := s.env.Releases.History(req.Name)
+	crls, err := s.env.Releases.Last(req.Name)
 	if err != nil {
 		return nil, nil, err
 	}
-	if len(h) <= 1 {
-		return nil, nil, errors.New("no revision to rollback")
-	}
-
-	relutil.SortByRevision(h)
-	crls := h[len(h)-1]
 
 	rbv := req.Version
 	if req.Version == 0 {