cli: create backups for CRDs and their resources

These backups could be used in case an upgrade
misbehaves after helm declared it as successful.
The manual backups are required as helm-rollback
won't touch custom resources and changes to CRDs
delete resources of the old version.

cli/internal/helm/backup.go

@@ -0,0 +1,80 @@
+/*
+Copyright (c) Edgeless Systems GmbH
+
+SPDX-License-Identifier: AGPL-3.0-only
+*/
+
+package helm
+
+import (
+	"context"
+	"fmt"
+	"path/filepath"
+
+	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/yaml"
+)
+
+const (
+	crdBackupFolder = "constellation-upgrade/backups/crds/"
+	backupFolder    = "constellation-upgrade/backups/"
+)
+
+func (c *Client) backupCRDs(ctx context.Context) ([]apiextensionsv1.CustomResourceDefinition, error) {
+	crds, err := c.kubectl.GetCRDs(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("getting CRDs: %w", err)
+	}
+
+	if err := c.fs.MkdirAll(crdBackupFolder); err != nil {
+		return nil, fmt.Errorf("creating backup dir: %w", err)
+	}
+	for i := range crds {
+		path := filepath.Join(crdBackupFolder, crds[i].Name+".yaml")
+
+		// We have to manually set kind/apiversion because of a long-standing limitation of the API:
+		// https://github.com/kubernetes/kubernetes/issues/3030#issuecomment-67543738
+		// The comment states that kind/version are encoded in the type.
+		// The package holding the CRD type encodes the version.
+		crds[i].Kind = "CustomResourceDefinition"
+		crds[i].APIVersion = "apiextensions.k8s.io/v1"
+
+		yamlBytes, err := yaml.Marshal(crds[i])
+		if err != nil {
+			return nil, err
+		}
+		if err := c.fs.Write(path, yamlBytes); err != nil {
+			return nil, err
+		}
+
+		c.log.Debugf("Created backup crd: %s", path)
+	}
+	return crds, nil
+}
+
+func (c *Client) backupCRs(ctx context.Context, crds []apiextensionsv1.CustomResourceDefinition) error {
+	for _, crd := range crds {
+		for _, version := range crd.Spec.Versions {
+			gvr := schema.GroupVersionResource{Group: crd.Spec.Group, Version: version.Name, Resource: crd.Spec.Names.Plural}
+			crs, err := c.kubectl.GetCRs(ctx, gvr)
+			if err != nil {
+				return fmt.Errorf("retrieving CR %s: %w", crd.Name, err)
+			}
+
+			for _, cr := range crs {
+				path := filepath.Join(backupFolder, cr.GetName()+".yaml")
+				yamlBytes, err := yaml.Marshal(cr.Object)
+				if err != nil {
+					return err
+				}
+				if err := c.fs.Write(path, yamlBytes); err != nil {
+					return err
+				}
+			}
+		}
+
+		c.log.Debugf("Created backups for resource type: %s", crd.Name)
+	}
+	return nil
+}