kubeadm: add logic for patching components in util/patches

cmd/kubeadm/app/util/BUILD

@@ -89,6 +89,7 @@ filegroup(
         "//cmd/kubeadm/app/util/kubeconfig:all-srcs",
         "//cmd/kubeadm/app/util/kustomize:all-srcs",
         "//cmd/kubeadm/app/util/output:all-srcs",
+        "//cmd/kubeadm/app/util/patches:all-srcs",
         "//cmd/kubeadm/app/util/pkiutil:all-srcs",
         "//cmd/kubeadm/app/util/pubkeypin:all-srcs",
         "//cmd/kubeadm/app/util/runtime:all-srcs",

cmd/kubeadm/app/util/patches/BUILD

@@ -0,0 +1,40 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["patches.go"],
+    importpath = "k8s.io/kubernetes/cmd/kubeadm/app/util/patches",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//staging/src/k8s.io/apimachinery/pkg/types:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/strategicpatch:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/util/yaml:go_default_library",
+        "//vendor/github.com/evanphx/json-patch:go_default_library",
+        "//vendor/github.com/pkg/errors:go_default_library",
+        "//vendor/sigs.k8s.io/yaml:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["patches_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//staging/src/k8s.io/api/core/v1:go_default_library",
+        "//staging/src/k8s.io/apimachinery/pkg/types:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

cmd/kubeadm/app/util/patches/patches.go

@@ -0,0 +1,342 @@
+/*
+Copyright 2020 The Kubernetes 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 patches
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"sync"
+
+	jsonpatch "github.com/evanphx/json-patch"
+	"github.com/pkg/errors"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/apimachinery/pkg/util/strategicpatch"
+	utilyaml "k8s.io/apimachinery/pkg/util/yaml"
+	"sigs.k8s.io/yaml"
+)
+
+// PatchTarget defines a target to be patched, such as a control-plane static Pod.
+type PatchTarget struct {
+	// Name must be the name of a known target. In the case of Kubernetes objects
+	// this is likely to match the ObjectMeta.Name of a target.
+	Name string
+
+	// StrategicMergePatchObject is only used for strategic merge patches.
+	// It represents the underlying object type that is patched - e.g. "v1.Pod"
+	StrategicMergePatchObject interface{}
+
+	// Data must contain the bytes that will be patched.
+	Data []byte
+}
+
+// PatchManager defines an object that can apply patches.
+type PatchManager struct {
+	patchSets    []*patchSet
+	knownTargets []string
+	output       io.Writer
+}
+
+// patchSet defines a set of patches of a certain type that can patch a PatchTarget.
+type patchSet struct {
+	targetName string
+	patchType  types.PatchType
+	patches    []string
+}
+
+// String() is used for unit-testing.
+func (ps *patchSet) String() string {
+	return fmt.Sprintf(
+		"{%q, %q, %#v}",
+		ps.targetName,
+		ps.patchType,
+		ps.patches,
+	)
+}
+
+var (
+	pathLock  = &sync.RWMutex{}
+	pathCache = map[string]*PatchManager{}
+
+	patchTypes = map[string]types.PatchType{
+		"json":      types.JSONPatchType,
+		"merge":     types.MergePatchType,
+		"strategic": types.StrategicMergePatchType,
+		"":          types.StrategicMergePatchType, // Default
+	}
+	patchTypeList    = []string{"json", "merge", "strategic"}
+	patchTypesJoined = strings.Join(patchTypeList, "|")
+	knownExtensions  = []string{"json", "yaml"}
+
+	regExtension = regexp.MustCompile(`.+\.(` + strings.Join(knownExtensions, "|") + `)$`)
+)
+
+// GetPatchManagerForPath creates a patch manager that can be used to apply patches to "knownTargets".
+// "path" should contain patches that can be used to patch the "knownTargets".
+// If "output" is non-nil, messages about actions performed by the manager would go on this io.Writer.
+func GetPatchManagerForPath(path string, knownTargets []string, output io.Writer) (*PatchManager, error) {
+	pathLock.RLock()
+	if pm, known := pathCache[path]; known {
+		pathLock.RUnlock()
+		return pm, nil
+	}
+	pathLock.RUnlock()
+
+	if output == nil {
+		output = ioutil.Discard
+	}
+
+	fmt.Fprintf(output, "[patches] Reading patches from path %q\n", path)
+
+	// Get the files in the path.
+	patchSets, patchFiles, ignoredFiles, err := getPatchSetsFromPath(path, knownTargets, output)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(patchFiles) > 0 {
+		fmt.Fprintf(output, "[patches] Found the following patch files: %v\n", patchFiles)
+	}
+	if len(ignoredFiles) > 0 {
+		fmt.Fprintf(output, "[patches] Ignored the following files: %v\n", ignoredFiles)
+	}
+
+	pm := &PatchManager{
+		patchSets:    patchSets,
+		knownTargets: knownTargets,
+		output:       output,
+	}
+	pathLock.Lock()
+	pathCache[path] = pm
+	pathLock.Unlock()
+
+	return pm, nil
+}
+
+// ApplyPatchesToTarget takes a patch target and patches its "Data" using the patches
+// stored in the patch manager. The resulted "Data" is always converted to JSON.
+func (pm *PatchManager) ApplyPatchesToTarget(patchTarget *PatchTarget) error {
+	var err error
+	var patchedData []byte
+
+	var found bool
+	for _, pt := range pm.knownTargets {
+		if pt == patchTarget.Name {
+			found = true
+			break
+		}
+	}
+	if !found {
+		return errors.Errorf("unknown patch target name %q, must be one of %v", patchTarget.Name, pm.knownTargets)
+	}
+
+	// Always convert the target data to JSON.
+	patchedData, err = yaml.YAMLToJSON(patchTarget.Data)
+	if err != nil {
+		return err
+	}
+
+	// Iterate over the patchSets.
+	for _, patchSet := range pm.patchSets {
+		if patchSet.targetName != patchTarget.Name {
+			continue
+		}
+
+		// Iterate over the patches in the patchSets.
+		for _, patch := range patchSet.patches {
+			patchBytes := []byte(patch)
+
+			// Patch based on the patch type.
+			switch patchSet.patchType {
+
+			// JSON patch.
+			case types.JSONPatchType:
+				var patchObj jsonpatch.Patch
+				patchObj, err = jsonpatch.DecodePatch(patchBytes)
+				if err == nil {
+					patchedData, err = patchObj.Apply(patchedData)
+				}
+
+			// Merge patch.
+			case types.MergePatchType:
+				patchedData, err = jsonpatch.MergePatch(patchedData, patchBytes)
+
+			// Strategic merge patch.
+			case types.StrategicMergePatchType:
+				patchedData, err = strategicpatch.StrategicMergePatch(
+					patchedData,
+					patchBytes,
+					patchTarget.StrategicMergePatchObject,
+				)
+			}
+
+			if err != nil {
+				return errors.Wrapf(err, "could not apply the following patch of type %q to target %q:\n%s\n",
+					patchSet.patchType,
+					patchTarget.Name,
+					patch)
+			}
+			fmt.Fprintf(pm.output, "[patches] Applied patch of type %q to target %q\n", patchSet.patchType, patchTarget.Name)
+		}
+
+		// Update the data for this patch target.
+		patchTarget.Data = patchedData
+	}
+
+	return nil
+}
+
+// parseFilename validates a file name and retrieves the encoded target name and patch type.
+// - On unknown extension or target name it returns a warning
+// - On unknown patch type it returns an error
+// - On success it returns a target name and patch type
+func parseFilename(fileName string, knownTargets []string) (string, types.PatchType, error, error) {
+	// Return a warning if the extension cannot be matched.
+	if !regExtension.MatchString(fileName) {
+		return "", "", errors.Errorf("the file extension must be one of %v", knownExtensions), nil
+	}
+
+	regFileNameSplit := regexp.MustCompile(
+		fmt.Sprintf(`^(%s)([^.+\n]*)?(\+)?(%s)?`, strings.Join(knownTargets, "|"), patchTypesJoined),
+	)
+	// Extract the target name and patch type. The resulting sub-string slice would look like this:
+	//   [full-match, targetName, suffix, +, patchType]
+	sub := regFileNameSplit.FindStringSubmatch(fileName)
+	if sub == nil {
+		return "", "", errors.Errorf("unknown target, must be one of %v", knownTargets), nil
+	}
+	targetName := sub[1]
+
+	if len(sub[3]) > 0 && len(sub[4]) == 0 {
+		return "", "", nil, errors.Errorf("unknown or missing patch type after '+', must be one of %v", patchTypeList)
+	}
+	patchType := patchTypes[sub[4]]
+
+	return targetName, patchType, nil, nil
+}
+
+// createPatchSet creates a patchSet object, by splitting the given "data" by "\n---".
+func createPatchSet(targetName string, patchType types.PatchType, data string) (*patchSet, error) {
+	var patches []string
+
+	// Split the patches and convert them to JSON.
+	// Data that is already JSON will not cause an error.
+	buf := bytes.NewBuffer([]byte(data))
+	reader := utilyaml.NewYAMLReader(bufio.NewReader(buf))
+	for {
+		patch, err := reader.Read()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, errors.Wrapf(err, "could not split patches for data:\n%s\n", data)
+		}
+
+		patch = bytes.TrimSpace(patch)
+		if len(patch) == 0 {
+			continue
+		}
+
+		patchJSON, err := yaml.YAMLToJSON(patch)
+		if err != nil {
+			return nil, errors.Wrapf(err, "could not convert patch to JSON:\n%s\n", patch)
+		}
+		patches = append(patches, string(patchJSON))
+	}
+
+	return &patchSet{
+		targetName: targetName,
+		patchType:  patchType,
+		patches:    patches,
+	}, nil
+}
+
+// getPatchSetsFromPath walks a path, ignores sub-directories and non-patch files, and
+// returns a list of patchFile objects.
+func getPatchSetsFromPath(targetPath string, knownTargets []string, output io.Writer) ([]*patchSet, []string, []string, error) {
+	patchFiles := []string{}
+	ignoredFiles := []string{}
+	patchSets := []*patchSet{}
+
+	// Check if targetPath is a directory.
+	info, err := os.Lstat(targetPath)
+	if err != nil {
+		goto return_path_error
+	}
+	if !info.IsDir() {
+		err = errors.New("not a directory")
+		goto return_path_error
+	}
+
+	err = filepath.Walk(targetPath, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		// Sub-directories and "." are ignored.
+		if info.IsDir() {
+			return nil
+		}
+
+		baseName := info.Name()
+
+		// Parse the filename and retrieve the target and patch type
+		targetName, patchType, warn, err := parseFilename(baseName, knownTargets)
+		if err != nil {
+			return err
+		}
+		if warn != nil {
+			fmt.Fprintf(output, "[patches] Ignoring file %q: %v\n", baseName, warn)
+			ignoredFiles = append(ignoredFiles, baseName)
+			return nil
+		}
+
+		// Read the patch file.
+		data, err := ioutil.ReadFile(path)
+		if err != nil {
+			return errors.Wrapf(err, "could not read the file %q", path)
+		}
+
+		if len(data) == 0 {
+			fmt.Fprintf(output, "[patches] Ignoring empty file: %q\n", baseName)
+			ignoredFiles = append(ignoredFiles, baseName)
+			return nil
+		}
+
+		// Create a patchSet object.
+		patchSet, err := createPatchSet(targetName, patchType, string(data))
+		if err != nil {
+			return err
+		}
+
+		patchFiles = append(patchFiles, baseName)
+		patchSets = append(patchSets, patchSet)
+		return nil
+	})
+
+return_path_error:
+	if err != nil {
+		return nil, nil, nil, errors.Wrapf(err, "could not list patch files for path %q", targetPath)
+	}
+
+	return patchSets, patchFiles, ignoredFiles, nil
+}