Add Chart image baking

baker/bake.go

@@ -0,0 +1,211 @@
+/*
+Copyright 2025 The cert-manager Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package baker
+
+import (
+	"context"
+	"fmt"
+	"maps"
+	"slices"
+	"strings"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+type BakeReference struct {
+	Repository string
+	Tag        string
+	Digest     string
+}
+
+func ParseBakeReference(value string) (bakeInput BakeReference) {
+	// extract digest from value
+	if digestRef, err := name.NewDigest(value); err == nil {
+		bakeInput.Repository = digestRef.Context().String()
+		bakeInput.Digest = digestRef.DigestStr()
+	}
+
+	// extract tag from value
+	if tagRef, err := name.NewTag(value); err == nil {
+		bakeInput.Repository = tagRef.Context().String()
+		bakeInput.Tag = tagRef.TagStr()
+	}
+
+	return bakeInput
+}
+
+func (br BakeReference) Reference() name.Reference {
+	repo, _ := name.NewRepository(br.Repository)
+	if br.Digest != "" {
+		return repo.Digest(br.Digest)
+	}
+	return repo.Tag(br.Tag)
+}
+
+func (br BakeReference) String() string {
+	var builder strings.Builder
+	_, _ = builder.WriteString(br.Repository)
+	if br.Tag != "" {
+		_, _ = builder.WriteString(":")
+		_, _ = builder.WriteString(br.Tag)
+	}
+	if br.Digest != "" {
+		_, _ = builder.WriteString("@")
+		_, _ = builder.WriteString(br.Digest)
+	}
+	return builder.String()
+}
+
+type BakeInput = BakeReference
+
+func (bi BakeInput) Find(ctx context.Context) (BakeOutput, error) {
+	desc, err := remote.Head(bi.Reference(), remote.WithContext(ctx))
+	if err != nil {
+		return BakeReference{}, fmt.Errorf("failed to pull %s", bi)
+	}
+
+	return BakeReference{
+		Repository: bi.Repository,
+		Digest:     desc.Digest.String(),
+		Tag:        bi.Tag,
+	}, nil
+}
+
+type BakeOutput = BakeReference
+
+func Extract(ctx context.Context, inputPath string) (map[string]BakeInput, error) {
+	results := map[string]BakeInput{}
+
+	values, err := readValuesYAML(inputPath)
+	if err != nil {
+		return nil, err
+	}
+
+	if _, err := allNestedStringValues(values, nil, func(path []string, value string) (string, error) {
+		if path[len(path)-1] != "_defaultReference" {
+			return value, nil
+		}
+
+		bakeInput := ParseBakeReference(value)
+		if bakeInput == (BakeInput{}) {
+			return "", fmt.Errorf("invalid _defaultReference value: %q", value)
+		}
+
+		results[strings.Join(path, ".")] = bakeInput
+
+		return value, nil
+	}); err != nil {
+		return nil, err
+	}
+
+	return results, nil
+}
+
+type BakeAction struct {
+	In  BakeInput  `json:"in"`
+	Out BakeOutput `json:"out"`
+}
+
+func Bake(ctx context.Context, inputPath string, outputPath string, valuesPaths []string) (map[string]BakeAction, error) {
+	results := map[string]BakeAction{}
+	return results, modifyValuesYAML(inputPath, outputPath, func(values map[string]any) (map[string]any, error) {
+		replacedValuePaths := map[string]struct{}{}
+		newValues, err := allNestedStringValues(values, nil, func(path []string, value string) (string, error) {
+			if path[len(path)-1] != "_defaultReference" {
+				return value, nil
+			}
+
+			bakeInput := ParseBakeReference(value)
+			if bakeInput == (BakeInput{}) {
+				return "", fmt.Errorf("invalid _defaultReference value: %q", value)
+			}
+
+			bakeOutput, err := bakeInput.Find(ctx)
+			if err != nil {
+				return "", err
+			}
+
+			pathString := strings.Join(path, ".")
+			replacedValuePaths[pathString] = struct{}{}
+			results[pathString] = BakeAction{
+				In:  bakeInput,
+				Out: bakeOutput,
+			}
+
+			return bakeOutput.String(), nil
+		})
+		if err != nil {
+			return nil, err
+		}
+
+		if len(replacedValuePaths) > len(valuesPaths) {
+			return nil, fmt.Errorf("too many value paths were replaced: %v", slices.Collect(maps.Keys(replacedValuePaths)))
+		}
+		for _, valuesPath := range valuesPaths {
+			if _, ok := replacedValuePaths[valuesPath]; !ok {
+				return nil, fmt.Errorf("path was not replaced: %s", valuesPath)
+			}
+		}
+
+		return newValues.(map[string]any), nil
+	})
+}
+
+func allNestedStringValues(object any, path []string, fn func(path []string, value string) (string, error)) (any, error) {
+	switch t := object.(type) {
+	case map[string]any:
+		for key, value := range t {
+			keyPath := append(path, key)
+			if stringValue, ok := value.(string); ok {
+				newValue, err := fn(slices.Clone(keyPath), stringValue)
+				if err != nil {
+					return nil, err
+				}
+				t[key] = newValue
+			} else {
+				newValue, err := allNestedStringValues(value, keyPath, fn)
+				if err != nil {
+					return nil, err
+				}
+				t[key] = newValue
+			}
+		}
+	case map[string]string:
+		for key, stringValue := range t {
+			keyPath := append(path, key)
+			newValue, err := fn(slices.Clone(keyPath), stringValue)
+			if err != nil {
+				return nil, err
+			}
+			t[key] = newValue
+		}
+	case []any:
+		for i, value := range t {
+			path = append(path, fmt.Sprintf("%d", i))
+			newValue, err := allNestedStringValues(value, path, fn)
+			if err != nil {
+				return nil, err
+			}
+			t[i] = newValue
+		}
+	default:
+		// ignore object
+	}
+
+	return object, nil
+}

baker/modify_values.go

@@ -0,0 +1,157 @@
+/*
+Copyright 2025 The cert-manager Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package baker
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// inplaceReadValuesYAML reads the provided chart tar file and returns the values
+func readValuesYAML(inputPath string) (map[string]any, error) {
+	var result map[string]any
+	return result, modifyValuesYAML(inputPath, "", func(m map[string]any) (map[string]any, error) {
+		result = m
+		return m, nil
+	})
+}
+
+type modFunction func(map[string]any) (map[string]any, error)
+
+func modifyValuesYAML(inFilePath string, outFilePath string, modFn modFunction) error {
+	inReader, err := os.Open(inFilePath)
+	if err != nil {
+		return err
+	}
+	defer inReader.Close()
+
+	outWriter := io.Discard
+	if outFilePath != "" {
+		outFile, err := os.Create(outFilePath)
+		if err != nil {
+			return err
+		}
+		defer outFile.Close()
+
+		outWriter = outFile
+	}
+
+	if strings.HasSuffix(inFilePath, ".tgz") {
+		if err := modifyTarStreamValuesYAML(inReader, outWriter, modFn); err != nil {
+			return err
+		}
+	} else {
+		if err := modifyStreamValuesYAML(inReader, outWriter, modFn); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func modifyTarStreamValuesYAML(in io.Reader, out io.Writer, modFn modFunction) error {
+	inFileDecompressed, err := gzip.NewReader(in)
+	if err != nil {
+		return err
+	}
+	defer inFileDecompressed.Close()
+	tr := tar.NewReader(inFileDecompressed)
+
+	outFileCompressed, err := gzip.NewWriterLevel(out, gzip.BestCompression)
+	if err != nil {
+		return err
+	}
+	// see https://github.com/helm/helm/blob/b25a51b291b930ef05ed0f4a9ea7cce073c10f63/pkg/chart/v2/util/save.go#L35C28-L35C67
+	// seems like an easter egg, but keep it for "backwards compatibility" :)
+	outFileCompressed.Extra = []byte("+aHR0cHM6Ly95b3V0dS5iZS96OVV6MWljandyTQo=")
+	outFileCompressed.Comment = "Helm"
+	defer outFileCompressed.Close()
+	tw := tar.NewWriter(outFileCompressed)
+	defer tw.Close()
+
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			break // End of archive
+		}
+		if err != nil {
+			return err
+		}
+
+		const maxValuesYAMLSize = 2 * 1024 * 1024 // 2MB
+		limitedReader := &io.LimitedReader{
+			R: tr,
+			N: maxValuesYAMLSize,
+		}
+
+		if strings.HasSuffix(hdr.Name, "/values.yaml") {
+			var modifiedContent bytes.Buffer
+			if err := modifyStreamValuesYAML(limitedReader, &modifiedContent, modFn); err != nil {
+				return err
+			}
+
+			// Update header size
+			hdr.Size = int64(modifiedContent.Len())
+
+			// Write updated header and content
+			if err := tw.WriteHeader(hdr); err != nil {
+				return err
+			}
+			if _, err := tw.Write(modifiedContent.Bytes()); err != nil {
+				return err
+			}
+		} else {
+			// Stream other files unchanged
+			if err := tw.WriteHeader(hdr); err != nil {
+				return err
+			}
+			if _, err := io.Copy(tw, limitedReader); err != nil {
+				return err
+			}
+		}
+
+		if limitedReader.N <= 0 {
+			return fmt.Errorf("values.yaml is larger than %v bytes", maxValuesYAMLSize)
+		}
+	}
+
+	return nil
+}
+
+func modifyStreamValuesYAML(in io.Reader, out io.Writer, modFn modFunction) error {
+	// Parse YAML
+	var data map[string]any
+	if err := yaml.NewDecoder(in).Decode(&data); err != nil {
+		return err
+	}
+
+	// Modify YAML
+	data, err := modFn(data)
+	if err != nil {
+		return err
+	}
+
+	// Marshal back to YAML
+	return yaml.NewEncoder(out).Encode(data)
+}