feat: Update upgrade-matrix.yaml in post-upgrade based on env variable

hack/release/cmd/postrelease/postrelease.go

@@ -8,6 +8,7 @@ import (
 	"github.com/Masterminds/semver/v3"
 	"github.com/mesosphere/kommander-applications/hack/release/pkg/appversion"
 	"github.com/mesosphere/kommander-applications/hack/release/pkg/chartversion"
+	"github.com/mesosphere/kommander-applications/hack/release/pkg/upgradematrix"
 	"github.com/spf13/cobra"
 )
 
@@ -54,6 +55,14 @@ func init() { //nolint:gochecknoinits // Initializing cobra application.
 			}
 
 			fmt.Fprintf(cmd.OutOrStdout(), "Updated Kommander chart version to %s", chartVersion)
+
+			if err := upgradematrix.UpdateUpgradeMatrix(
+				cmd.Context(),
+				kommanderApplicationsRepo,
+			); err != nil {
+				return err
+			}
+
 			return nil
 		},
 	}

hack/release/pkg/upgradematrix/upgradematrix.go

@@ -0,0 +1,44 @@
+package upgradematrix
+
+import (
+	"context"
+	"errors"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	upgradeMatrixEnv  = "NKP_RELEASE_AUTOMATION_UPGRADE_MATRIX"
+	upgradeMatrixFile = "upgrade-matrix.yaml"
+)
+
+var ErrIncorrectFormat = errors.New("upgrade matrix does not appear to be in the correct format, unable to update upgrade-matrix.yaml")
+
+// UpdateUpgradeMatrix updates the upgrade-matrix.yaml file in the kommander-applications repository with the contents \
+// of the upgradeMatrixEnv environment variable.
+func UpdateUpgradeMatrix(ctx context.Context, kommanderApplicationsRepo string) error {
+	// Get the upgrade matrix environment variable
+	upgradeMatrix := os.Getenv(upgradeMatrixEnv)
+	if upgradeMatrix == "" {
+		log.Printf("upgrade matrix environment variable %s is empty, unable to update upgrade-matrix.yaml", upgradeMatrixEnv)
+		return nil
+	}
+
+	// Check that upgradeMatrix appears to be correct
+	if !strings.HasPrefix(upgradeMatrix, "upgrades:") {
+		return ErrIncorrectFormat
+	}
+
+	// Write the upgrade matrix to the file
+	err := os.WriteFile(filepath.Join(kommanderApplicationsRepo, upgradeMatrixFile), []byte(upgradeMatrix), 0644)
+	if err != nil {
+		log.Print("cannot write upgrade-matrix.yaml")
+		return err
+	}
+
+	log.Print("Updated upgrade matrix")
+
+	return nil
+}

hack/release/pkg/upgradematrix/upgradematrix_test.go

@@ -0,0 +1,83 @@
+package upgradematrix
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+const testFile = `upgrades:
+  - from: v1.2.3
+    to: v4.5.6
+    k8s_version: "1.34"
+`
+
+const expectedContent = `upgrades:
+  - from: v2.8.0
+    to: v2.8.2-dev
+    k8s_version: "1.28"
+  - from: v2.8.1
+    to: v2.8.2-dev
+    k8s_version: "1.28"
+  - from: v2.8.2-dev
+    to: v2.12.0-dev
+    k8s_version: "1.28"
+`
+
+func TestUpdateUpgradeMatrix(t *testing.T) {
+	dir := fetchRepo(t)
+
+	// Replace the existing file with known test data
+	err := os.WriteFile(filepath.Join(dir, "upgrade-matrix.yaml"), []byte(testFile), 0644)
+	require.NoError(t, err)
+
+	// Expected update value
+	err = os.Setenv(upgradeMatrixEnv, expectedContent)
+	require.NoError(t, err)
+
+	err = UpdateUpgradeMatrix(context.Background(), dir)
+	require.NoError(t, err)
+
+	// Check that the file has been regenerated
+	fileContent, err := os.ReadFile(filepath.Join(dir, "upgrade-matrix.yaml"))
+	require.NoError(t, err)
+
+	require.Equal(t, string(fileContent), expectedContent)
+	require.NotContains(t, string(fileContent), testFile)
+}
+
+func TestUpdateUpgradeMatrixNoEnv(t *testing.T) {
+	dir := fetchRepo(t)
+
+	// Replace the existing file with known test data
+	err := os.WriteFile(filepath.Join(dir, "upgrade-matrix.yaml"), []byte(testFile), 0644)
+	require.NoError(t, err)
+
+	// Ensure that the environment variable is empty
+	err = os.Setenv(upgradeMatrixEnv, "")
+	require.NoError(t, err)
+
+	err = UpdateUpgradeMatrix(context.Background(), dir)
+	require.NoError(t, err)
+
+	// Check that the file has *not* been regenerated
+	fileContent, err := os.ReadFile(filepath.Join(dir, "upgrade-matrix.yaml"))
+	require.NoError(t, err)
+
+	require.Equal(t, string(fileContent), testFile)
+}
+
+func fetchRepo(t *testing.T) string {
+	t.Helper()
+
+	dir := t.TempDir()
+	cmd := exec.Command("git", "clone", strings.Repeat("../", 4), dir)
+	require.NoError(t, cmd.Run())
+
+	return dir
+}