cli: save Helm charts to disk before running upgrades (#2305)

Signed-off-by: Daniel Weiße <dw@edgeless.systems>

cli/internal/helm/chartutil.go

@@ -0,0 +1,86 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package helm
+
+import (
+	"fmt"
+	"path/filepath"
+
+	"github.com/edgelesssys/constellation/v2/internal/file"
+	"helm.sh/helm/v3/pkg/chart"
+	"helm.sh/helm/v3/pkg/chartutil"
+)
+
+// saveChartToDisk saves a chart as files in a directory.
+//
+// This takes the chart name, and creates a new subdirectory inside of the given dest
+// directory, writing the chart's contents to that subdirectory.
+// Dependencies are written using the same format, instead of writing them as tar files
+//
+// View the SaveDir implementation in chartutil as reference: https://github.com/helm/helm/blob/3a31588ad33fe3b89af5a2a54ee1d25bfe6eaa5e/pkg/chartutil/save.go#L40
+func saveChartToDisk(c *chart.Chart, dest string, fileHandler file.Handler) error {
+	// Create the chart directory
+	outdir := filepath.Join(dest, c.Name())
+	if fi, err := fileHandler.Stat(outdir); err == nil && !fi.IsDir() {
+		return fmt.Errorf("file %s already exists and is not a directory", outdir)
+	}
+	if err := fileHandler.MkdirAll(outdir); err != nil {
+		return err
+	}
+
+	// Save the chart file.
+	if err := chartutil.SaveChartfile(filepath.Join(outdir, chartutil.ChartfileName), c.Metadata); err != nil {
+		return err
+	}
+
+	// Save values.yaml
+	for _, f := range c.Raw {
+		if f.Name == chartutil.ValuesfileName {
+			vf := filepath.Join(outdir, chartutil.ValuesfileName)
+			if err := writeFile(vf, f.Data, fileHandler); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Save values.schema.json if it exists
+	if c.Schema != nil {
+		filename := filepath.Join(outdir, chartutil.SchemafileName)
+		if err := writeFile(filename, c.Schema, fileHandler); err != nil {
+			return err
+		}
+	}
+
+	// Save templates and files
+	for _, o := range [][]*chart.File{c.Templates, c.Files} {
+		for _, f := range o {
+			n := filepath.Join(outdir, f.Name)
+			if err := writeFile(n, f.Data, fileHandler); err != nil {
+				return err
+			}
+		}
+	}
+
+	// Save dependencies
+	base := filepath.Join(outdir, chartutil.ChartsDir)
+	for _, dep := range c.Dependencies() {
+		// Don't write dependencies as tar files
+		// Instead recursively use saveChartToDisk
+		if err := saveChartToDisk(dep, base, fileHandler); err != nil {
+			return fmt.Errorf("saving %s: %w", dep.ChartFullPath(), err)
+		}
+	}
+
+	return nil
+}
+
+func writeFile(name string, content []byte, fileHandler file.Handler) error {
+	if err := fileHandler.MkdirAll(filepath.Dir(name)); err != nil {
+		return err
+	}
+	return fileHandler.Write(name, content)
+}