feat: add version-aware helm chart upgrade callbacks

Some helm chart upgrades require side-effects that a plain `helm upgrade` cannot perform, such as deleting deployments whose immutable selectors changed. Charts may now register pre and post upgrade hooks against a target version; applicable hooks fire in ascending semver order, each bracketed around an upgrade to its version, with a final upgrade to the chart's configured version when needed. The new `keda-add-ons-http` 0.12.2 hook deletes the chart-managed deployments before the upgrade so the new selectors take effect cleanly.

plugins/scheduler-k3s/chart_hooks_test.go

@@ -0,0 +1,159 @@
+package scheduler_k3s
+
+import (
+	"context"
+	"testing"
+)
+
+func makeHook(version string) ChartHook {
+	noop := func(context.Context, KubernetesClient, HelmChart, Release) error { return nil }
+	return ChartHook{
+		TargetVersion: version,
+		PreUpgrade:    noop,
+	}
+}
+
+func versionsOf(hooks []ChartHook) []string {
+	out := make([]string, 0, len(hooks))
+	for _, hook := range hooks {
+		out = append(out, hook.TargetVersion)
+	}
+	return out
+}
+
+func equalStrings(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func TestSelectChartHooks(t *testing.T) {
+	previous := ChartHooks
+	t.Cleanup(func() { ChartHooks = previous })
+
+	ChartHooks = map[string][]ChartHook{
+		"chart-with-hooks": {
+			makeHook("0.12.0"),
+			makeHook("0.10.0"),
+			makeHook("0.11.0"),
+		},
+	}
+
+	cases := []struct {
+		name             string
+		releaseName      string
+		installedVersion string
+		targetVersion    string
+		want             []string
+		wantErr          bool
+	}{
+		{
+			name:             "fresh install yields no hooks",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "",
+			targetVersion:    "0.12.0",
+			want:             nil,
+		},
+		{
+			name:             "no hooks registered for release",
+			releaseName:      "chart-without-hooks",
+			installedVersion: "0.5.0",
+			targetVersion:    "0.6.0",
+			want:             nil,
+		},
+		{
+			name:             "single applicable hook returned",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.10.0",
+			targetVersion:    "0.11.0",
+			want:             []string{"0.11.0"},
+		},
+		{
+			name:             "all hooks below installed version excluded",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.12.0",
+			targetVersion:    "0.12.0",
+			want:             nil,
+		},
+		{
+			name:             "all applicable hooks returned in ascending semver order",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.9.0",
+			targetVersion:    "0.12.0",
+			want:             []string{"0.10.0", "0.11.0", "0.12.0"},
+		},
+		{
+			name:             "partial coverage returns only unsatisfied hooks",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.10.0",
+			targetVersion:    "0.12.0",
+			want:             []string{"0.11.0", "0.12.0"},
+		},
+		{
+			name:             "target above all hooks still caps at chart target",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.9.0",
+			targetVersion:    "0.11.0",
+			want:             []string{"0.10.0", "0.11.0"},
+		},
+		{
+			name:             "unparseable installed version errors",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "not-a-version",
+			targetVersion:    "0.12.0",
+			wantErr:          true,
+		},
+		{
+			name:             "unparseable target version errors",
+			releaseName:      "chart-with-hooks",
+			installedVersion: "0.9.0",
+			targetVersion:    "not-a-version",
+			wantErr:          true,
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := selectChartHooks(tc.releaseName, tc.installedVersion, tc.targetVersion)
+			if tc.wantErr {
+				if err == nil {
+					t.Fatalf("expected error, got nil")
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+
+			gotVersions := versionsOf(got)
+			if !equalStrings(gotVersions, tc.want) {
+				t.Fatalf("versions mismatch: got %v, want %v", gotVersions, tc.want)
+			}
+		})
+	}
+}
+
+func TestSelectChartHooksTreatsLeadingVAsEqual(t *testing.T) {
+	previous := ChartHooks
+	t.Cleanup(func() { ChartHooks = previous })
+
+	ChartHooks = map[string][]ChartHook{
+		"chart-v-prefixed": {
+			makeHook("v1.13.3"),
+		},
+	}
+
+	got, err := selectChartHooks("chart-v-prefixed", "v1.12.0", "v1.13.3")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(got) != 1 || got[0].TargetVersion != "v1.13.3" {
+		t.Fatalf("expected v1.13.3 hook, got %v", versionsOf(got))
+	}
+}