ROX-24273: garbage collection for tenant-resources chart

fleetshard/pkg/central/reconciler/doc.go

@@ -0,0 +1,3 @@
+package reconciler
+
+//go:generate go run gen/main.go

fleetshard/pkg/central/reconciler/gen/main.go

@@ -0,0 +1,236 @@
+// This program generates a list of GVKs used by the tenant-resources helm chart for enabling garbage collection.
+//
+// To enable garbage collection without this list, we would need to...
+// - Manually maintain a list of GVKs present in the chart, which would be error-prone.
+// - Or have the reconciler list all objects for all possible GVKs, which would be very expensive.
+// - Switch to the native helm client or the helm operator, which would require a lot of changes.
+//
+// This program automatically generates that list.
+//
+// Process:
+// - It extract the GVKs that are present in the tenant-resources chart manifests
+// - It extract the GVKs that are already declared in the generated file
+// - It combines the two lists
+// - It writes the combined list to the generated file
+
+package main
+
+import (
+	"fmt"
+	"github.com/pkg/errors"
+	"io/fs"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"runtime"
+	"sort"
+	"strings"
+)
+
+var (
+	reconcilerDir           = path.Join(path.Dir(getCurrentFile()), "..")
+	outFile                 = fmt.Sprintf("%s/zzz_managed_resources.go", reconcilerDir)
+	tenantResourcesChartDir = path.Join(path.Dir(getCurrentFile()), "../../charts/data/tenant-resources/templates")
+	gvkRegex                = regexp.MustCompile(`schema.GroupVersionKind{Group: "(.*)", Version: "(.*)", Kind: "(.*)"},`)
+)
+
+const (
+	apiVersionPrefix = "apiVersion: "
+	kindPrefix       = "kind: "
+)
+
+func main() {
+	if err := generate(); err != nil {
+		panic(err)
+	}
+}
+
+type resourceMap map[schema.GroupVersionKind]bool
+
+func generate() error {
+
+	// Holds a map of GVKs that will be in the output file
+	// The value `bool` indicates that the resource is present in the tenant-resources helm chart
+	// If false, this means that the resource is only present in the generated file (for GVKs removed from the chart)
+	// But the GVK is still needed for garbage collection.
+	seen := resourceMap{}
+
+	// Finding GVKs used in the tenant-resources chart
+	if err := findGVKsInChart(tenantResourcesChartDir, seen); err != nil {
+		return err
+	}
+
+	// Finding GVKs already declared in the generated file
+	if err := findGVKsInGeneratedFile(seen); err != nil {
+		return err
+	}
+
+	// Re-generating the file
+	if err := generateGVKsList(seen); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func getCurrentFile() string {
+	_, file, _, _ := runtime.Caller(0)
+	return file
+}
+
+func generateGVKsList(seen resourceMap) error {
+	// Making sure resources are ordered (for deterministic output)
+	sorted := sortResourceKeys(seen)
+
+	builder := strings.Builder{}
+	builder.WriteString("// Code generated by fleetshard/pkg/central/reconciler/gen/main.go. DO NOT EDIT.\n")
+	builder.WriteString("package reconciler\n\n")
+	builder.WriteString("import (\n")
+	builder.WriteString("\t\"k8s.io/apimachinery/pkg/runtime/schema\"\n")
+	builder.WriteString(")\n\n")
+
+	builder.WriteString("// tenantChartResourceGVKs is a list of GroupVersionKind that...\n")
+	builder.WriteString("// - are present in the tenant-resources helm chart\n")
+	builder.WriteString("// - were present in a previous version of the chart. A comment will indicate that manual removal from the list is required.\n")
+
+	builder.WriteString("var tenantChartResourceGVKs = []schema.GroupVersionKind{\n")
+	for _, k := range sorted {
+		builder.WriteString(fmt.Sprintf("\tschema.GroupVersionKind{Group: %q, Version: %q, Kind: %q},", k.Group, k.Version, k.Kind))
+		stillInChart := seen[k]
+		if !stillInChart {
+			builder.WriteString(" // This resource was present in a previous version of the chart. Manual removal is required.")
+		}
+		builder.WriteString("\n")
+	}
+	builder.WriteString("}\n")
+
+	genFile, err := os.Create(outFile)
+	if err != nil {
+		return err
+	}
+	defer genFile.Close()
+
+	genFile.WriteString(builder.String())
+	return nil
+}
+
+func sortResourceKeys(seen resourceMap) []schema.GroupVersionKind {
+	sorted := make([]schema.GroupVersionKind, 0, len(seen))
+	for k := range seen {
+		sorted = append(sorted, k)
+	}
+	sort.Slice(sorted, func(i, j int) bool {
+		left := sorted[i]
+		right := sorted[j]
+		return left.String() < right.String()
+	})
+	return sorted
+}
+
+func findGVKsInGeneratedFile(seen resourceMap) error {
+	if _, err := os.Stat(outFile); err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+		return err
+	}
+
+	file, err := os.Open(outFile)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	fileBytes, err := os.ReadFile(outFile)
+	if err != nil {
+		return err
+	}
+
+	lines := strings.Split(string(fileBytes), "\n")
+
+	for _, line := range lines {
+		matches := gvkRegex.FindStringSubmatch(line)
+		if len(matches) != 4 {
+			continue
+		}
+		gvk := schema.GroupVersionKind{Group: matches[1], Version: matches[2], Kind: matches[3]}
+		isAlreadyPresent := seen[gvk]
+		seen[gvk] = isAlreadyPresent
+	}
+	return nil
+}
+
+func findGVKsInChart(chartDir string, seen resourceMap) error {
+	if err := filepath.WalkDir(chartDir, func(path string, d fs.DirEntry, err error) error {
+		if d.IsDir() {
+			return nil
+		}
+
+		ext := filepath.Ext(path)
+		if ext != ".yaml" && ext != ".yml" {
+			return nil
+		}
+
+		fileBytes, err := os.ReadFile(path)
+		if err != nil {
+			return err
+		}
+
+		if err := findGVKsInFile(fileBytes, seen); err != nil {
+			return fmt.Errorf("failed to parse file %q: %w", path, err)
+		}
+
+		return nil
+	}); err != nil {
+		return err
+	}
+	return nil
+}
+
+func splitFileIntoResources(fileBytes []byte) []string {
+	fileStr := string(fileBytes)
+	return strings.Split(fileStr, "---")
+}
+
+func findGVKsInFile(fileBytes []byte, seen resourceMap) error {
+	resources := splitFileIntoResources(fileBytes)
+	for _, resource := range resources {
+		gvk, ok, err := findResourceGVK(resource)
+		if err != nil {
+			return fmt.Errorf("failed to parse resource: %w", err)
+		}
+		if !ok {
+			return errors.New("resource GVK could not be parsed")
+		}
+		seen[gvk] = true
+	}
+	return nil
+}
+
+func findResourceGVK(resource string) (schema.GroupVersionKind, bool, error) {
+	lines := strings.Split(resource, "\n")
+	apiVersion := ""
+	kind := ""
+	for i := 0; i < len(lines); i++ {
+		if strings.HasPrefix(lines[i], apiVersionPrefix) {
+			apiVersion = strings.TrimSpace(strings.TrimPrefix(lines[i], apiVersionPrefix))
+			continue
+		}
+		if strings.HasPrefix(lines[i], kindPrefix) {
+			kind = strings.TrimSpace(strings.TrimPrefix(lines[i], kindPrefix))
+			continue
+		}
+	}
+	if len(apiVersion) == 0 || len(kind) == 0 {
+		return schema.GroupVersionKind{}, false, nil
+	}
+
+	groupVersion, err := schema.ParseGroupVersion(apiVersion)
+	if err != nil {
+		return schema.GroupVersionKind{}, false, err
+	}
+
+	return groupVersion.WithKind(kind), true, nil
+}