Improve mandiff by ignoring specified paths in manifests. Add yaml compare tool to only output diff with neat paths. (#225)

Author: elfinhe

go.mod

@@ -53,6 +53,7 @@ require (
 	github.com/golang/protobuf v1.3.1
 	github.com/golang/snappy v0.0.1 // indirect
 	github.com/google/btree v1.0.0 // indirect
+	github.com/google/go-cmp v0.3.0
 	github.com/google/gofuzz v1.0.0 // indirect
 	github.com/google/uuid v1.1.1 // indirect
 	github.com/googleapis/gnostic v0.2.0 // indirect

pkg/compare/compare.go

@@ -0,0 +1,121 @@
+// Copyright 2019 Istio 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 compare
+
+import (
+	"fmt"
+	"path/filepath"
+	"strings"
+
+	"github.com/google/go-cmp/cmp"
+	"sigs.k8s.io/yaml"
+
+	"istio.io/operator/pkg/tpath"
+)
+
+// YAMLCmpReporter is a custom reporter to generate tree based diff for YAMLs, used by cmp.Equal().
+type YAMLCmpReporter struct {
+	path     cmp.Path
+	diffTree map[string]interface{}
+}
+
+// PushStep implements interface to keep track of current path by pushing.
+// a step into YAMLCmpReporter.path
+func (r *YAMLCmpReporter) PushStep(ps cmp.PathStep) {
+	r.path = append(r.path, ps)
+}
+
+// PopStep implements interface to keep track of current path by popping a step out.
+// of YAMLCmpReporter.path
+func (r *YAMLCmpReporter) PopStep() {
+	r.path = r.path[:len(r.path)-1]
+}
+
+// Report implements interface to add diff path into YAMLCmpReporter.diffTree.
+func (r *YAMLCmpReporter) Report(rs cmp.Result) {
+	if !rs.Equal() {
+		vx, vy := r.path.Last().Values()
+		var dm string
+		if vx.IsValid() && !vy.IsValid() {
+			dm = fmt.Sprintf("%v ->", vx)
+		} else if !vx.IsValid() && vy.IsValid() {
+			dm = fmt.Sprintf("-> %v", vy)
+		} else if vx.IsValid() && vy.IsValid() {
+			dm = fmt.Sprintf("%v -> %v", vx, vy)
+		}
+		if r.diffTree == nil {
+			r.diffTree = make(map[string]interface{})
+		}
+		if err := tpath.WriteNode(r.diffTree, pathToStringList(r.path), dm); err != nil {
+			panic(err)
+		}
+	}
+}
+
+// String returns a text representation of diff tree.
+func (r *YAMLCmpReporter) String() string {
+	if len(r.diffTree) == 0 {
+		return ""
+	}
+	y, err := yaml.Marshal(r.diffTree)
+	if err != nil {
+		return err.Error()
+	}
+	return string(y)
+}
+
+// YAMLCmp compares two yaml texts, return a tree based diff text.
+func YAMLCmp(a, b string) string {
+	return YAMLCmpWithIgnore(a, b, nil)
+}
+
+// YAMLCmpWithIgnore compares two yaml texts, and ignores paths in ignorePaths.
+func YAMLCmpWithIgnore(a, b string, ignorePaths []string) string {
+	ao, bo := make(map[string]interface{}), make(map[string]interface{})
+	if err := yaml.Unmarshal([]byte(a), &ao); err != nil {
+		return err.Error()
+	}
+	if err := yaml.Unmarshal([]byte(b), &bo); err != nil {
+		return err.Error()
+	}
+	var r YAMLCmpReporter
+	cmp.Equal(ao, bo, cmp.Reporter(&r), genPathIgnoreOpt(ignorePaths))
+	return r.String()
+}
+
+// genPathIgnoreOpt returns a cmp.Option to ignore paths specified in parameter ignorePaths.
+func genPathIgnoreOpt(ignorePaths []string) cmp.Option {
+	return cmp.FilterPath(func(curPath cmp.Path) bool {
+		cp := strings.Join(pathToStringList(curPath), ".")
+		for _, ip := range ignorePaths {
+			if res, err := filepath.Match(ip, cp); err == nil && res {
+				return true
+			}
+		}
+		return false
+	}, cmp.Ignore())
+}
+
+func pathToStringList(path cmp.Path) (up []string) {
+	for _, step := range path {
+		switch t := step.(type) {
+		case cmp.MapIndex:
+			up = append(up, fmt.Sprintf("%v", t.Key()))
+		case cmp.SliceIndex:
+			up = append(up, fmt.Sprintf("%v", t.String()))
+		}
+	}
+	return
+}