pkg/helm: add wrapper to get the Helm history we expect

We expect to get the history in descending order by version and limited
to 1 version to get the last version so we can ensure the user has the
last version of the Helm chart.

However, it turns out the Helm API doesn't honor the Max config parameter and
returns the Helm history in a non-deterministic order.

This adds a wrapper function that sorts what the Helm API returns in the
way we expect and uses that.

Fixes #1442

cli/cmd/cluster/cluster.go

@@ -32,6 +32,7 @@ import (
 	"github.com/kinvolk/lokomotive/pkg/backend/local"
 	"github.com/kinvolk/lokomotive/pkg/components/util"
 	"github.com/kinvolk/lokomotive/pkg/config"
+	"github.com/kinvolk/lokomotive/pkg/helm"
 	"github.com/kinvolk/lokomotive/pkg/platform"
 	"github.com/kinvolk/lokomotive/pkg/terraform"
 )
@@ -309,9 +310,9 @@ func (c controlplaneUpdater) ensureComponent(component, namespace string) error
 	}
 
 	histClient := action.NewHistory(actionConfig)
-	histClient.Max = 1
+	histMax := 1
 
-	history, err := histClient.Run(component)
+	history, err := helm.GetHistory(histClient, component, histMax)
 	if err != nil && err != driver.ErrReleaseNotFound {
 		return fmt.Errorf("checking for chart history: %w", err)
 	}

pkg/helm/history.go

@@ -0,0 +1,54 @@
+// Copyright 2021 The Lokomotive Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package helm
+
+import (
+	"sort"
+
+	"helm.sh/helm/v3/pkg/release"
+)
+
+type releaseByVersionDesc []*release.Release
+
+func (rs releaseByVersionDesc) Len() int           { return len(rs) }
+func (rs releaseByVersionDesc) Less(i, j int) bool { return rs[i].Version < rs[j].Version }
+func (rs releaseByVersionDesc) Swap(i, j int)      { rs[i], rs[j] = rs[j], rs[i] }
+
+// HistoryClient allows mocking for tests.
+type HistoryClient interface {
+	Run(name string) ([]*release.Release, error)
+}
+
+// GetHistory returns at most max elements of the Helm history in descending
+// version order, that is, the first element returned is the newest version of
+// the release.
+//
+// See
+// https://github.com/helm/helm/blob/041ce5a2c17a58be0fcd5f5e16fb3e7e95fea622/cmd/helm/history.go#L115-L135.
+// When helm exposes this in the API we can get rid of this.
+func GetHistory(client HistoryClient, name string, max int) ([]*release.Release, error) {
+	history, err := client.Run(name)
+	if err != nil {
+		return nil, err
+	}
+
+	sort.Sort(sort.Reverse(releaseByVersionDesc(history)))
+
+	if max > len(history) {
+		max = len(history)
+	}
+
+	return history[:max], nil
+}

pkg/helm/history_test.go

@@ -0,0 +1,124 @@
+// Copyright 2021 The Lokomotive Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package helm_test
+
+import (
+	"testing"
+
+	"github.com/kinvolk/lokomotive/pkg/helm"
+
+	"github.com/google/go-cmp/cmp"
+	"helm.sh/helm/v3/pkg/release"
+)
+
+type mockHistory []*release.Release
+
+func newMockHistory(rs []*release.Release) mockHistory {
+	return rs
+}
+
+func (m mockHistory) Run(name string) ([]*release.Release, error) {
+	return m, nil
+}
+
+func TestGetHistory(t *testing.T) { //nolint:funlen
+	h := newMockHistory([]*release.Release{
+		{
+			Name:    "testRelease",
+			Version: 6,
+		},
+		{
+			Name:    "testRelease",
+			Version: 2,
+		},
+		{
+			Name:    "testRelease",
+			Version: 4,
+		},
+		{
+			Name:    "testRelease",
+			Version: 3,
+		},
+		{
+			Name:    "testRelease",
+			Version: 5,
+		},
+	})
+
+	type testCase struct {
+		name     string
+		max      int
+		expected []*release.Release
+	}
+
+	cases := []testCase{
+		{
+			name: "returns_at_most_given_max_elements",
+			max:  2,
+			expected: []*release.Release{
+				{
+					Name:    "testRelease",
+					Version: 6,
+				},
+				{
+					Name:    "testRelease",
+					Version: 5,
+				},
+			},
+		},
+		{
+			name: "returns_releases_with_descending_order_by_version",
+			max:  10,
+			expected: []*release.Release{
+				{
+					Name:    "testRelease",
+					Version: 6,
+				},
+				{
+					Name:    "testRelease",
+					Version: 5,
+				},
+				{
+					Name:    "testRelease",
+					Version: 4,
+				},
+				{
+					Name:    "testRelease",
+					Version: 3,
+				},
+				{
+					Name:    "testRelease",
+					Version: 2,
+				},
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			got, err := helm.GetHistory(h, "testRelease", tc.max)
+			if err != nil {
+				t.Fatalf("Getting history: %v", err)
+			}
+
+			if diff := cmp.Diff(got, tc.expected); diff != "" {
+				t.Fatalf("Unexpected history (-want +got)\n%s", diff)
+			}
+		})
+	}
+}