Fail PR if it has a structural schema change in a released version

hack/check-schema-changes.sh

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+
+# Copyright 2019 The Skaffold 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.
+
+
+# This check checks whether the PR compared to master contains any changes
+# in the config.go files under pkg/skaffold/schema. If yes, it checks if those changes
+# are structural changes or not.
+# If they are structural changes and the package is not "latest",
+# then we'll fail the PR as we assume anything else than latest is already released and
+# shouldn't be changed.
+# If the change is latest and it is released, we fail the PR for the same reason.
+# If the change is in latest and it is not released yet, it is fine to make changes.
+
+
+
+set +x
+
+go run hack/versions/cmd/schema_check/check.go

hack/checks.sh

@@ -20,6 +20,7 @@ RESET='\033[0m'
 
 echo "Running validation scripts..."
 scripts=(
+    "hack/check-schema-changes.sh"
     "hack/boilerplate.sh"
     "hack/gofmt.sh"
     "hack/linter.sh"
@@ -41,4 +42,4 @@ for s in "${scripts[@]}"; do
         fail=1
     fi
 done
-exit $fail
+exit $fail

hack/versions/cmd/schema_check/check.go

@@ -0,0 +1,28 @@
+/*
+Copyright 2019 The Skaffold 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 main
+
+import (
+	"github.com/GoogleContainerTools/skaffold/hack/versions/pkg/schema"
+	"github.com/sirupsen/logrus"
+)
+
+func main() {
+	if err := schema.RunSchemaCheckOnChangedFiles(); err != nil {
+		logrus.Fatal(err)
+	}
+}

hack/versions/pkg/diff/godiff.go

@@ -0,0 +1,118 @@
+/*
+Copyright 2019 The Skaffold 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 diff
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"sort"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+// CompareGoStructs returns an empty string iff aFile and bFile are valid go files
+// and the top level go struct declarations have the same fields independent of order.
+// It returns a semi-readable diff of the AST in case the two files are different.
+// Returns error when either of the go files are not parseable.
+func CompareGoStructs(aFile string, bFile string) (string, error) {
+	fset := token.NewFileSet()
+	astA, err := parser.ParseFile(fset, aFile, nil, parser.AllErrors)
+	if err != nil {
+		return "", err
+	}
+	astB, err := parser.ParseFile(fset, bFile, nil, parser.AllErrors)
+	if err != nil {
+		return "", err
+	}
+
+	return cmp.Diff(structsMap(astA), structsMap(astB)), nil
+}
+
+func structsMap(astB *ast.File) map[string]string {
+	bStructs := make(map[string]string)
+	for _, n := range astB.Decls {
+		decl, ok := n.(*ast.GenDecl)
+		if !ok {
+			continue
+		}
+		typeSec, ok := decl.Specs[0].(*ast.TypeSpec)
+		if !ok {
+			continue
+		}
+		structType, ok := typeSec.Type.(*ast.StructType)
+		if !ok {
+			continue
+		}
+		bStructs[typeSec.Name.Name] = fieldListString(structType)
+	}
+	logrus.Debugf("%+v", bStructs)
+	return bStructs
+}
+
+func fieldListString(structType *ast.StructType) string {
+	fieldListString := ""
+	fields := structType.Fields.List
+	sort.Slice(fields, func(i, j int) bool {
+		if len(fields[i].Names) == 0 {
+			return false
+		}
+		if len(fields[i].Names) > 0 && len(fields[j].Names) == 0 {
+			return true
+		}
+		return strings.Compare(fields[i].Names[0].Name, fields[j].Names[0].Name) > 0
+	})
+	for _, field := range fields {
+		tag := "'"
+		if field.Tag != nil {
+			tag = field.Tag.Value
+		}
+		fieldListString = fmt.Sprintf("%s %s type: %s tag: %s",
+			fieldListString,
+			field.Names,
+			baseTypeName(field.Type),
+			tag)
+	}
+	return fieldListString
+}
+
+// inspired by https://github.com/golang/go/blob/9b968df17782f21cc0af14c9d3c0bcf4cf3f911f/src/go/doc/reader.go#L100
+func baseTypeName(x ast.Expr) (name string) {
+	switch t := x.(type) {
+	case *ast.Ident:
+		return t.Name
+	case *ast.SelectorExpr:
+		if _, ok := t.X.(*ast.Ident); ok {
+			return t.Sel.Name
+		}
+	case *ast.ArrayType:
+		return "[]" + baseTypeName(t.Elt)
+	case *ast.MapType:
+		return "map[" + baseTypeName(t.Key) + "]" + baseTypeName(t.Value)
+	case *ast.ParenExpr:
+		return baseTypeName(t.X)
+	case *ast.StarExpr:
+		return "*" + baseTypeName(t.X)
+	default:
+		panic(fmt.Errorf("not covered %+v %+v ", t, x))
+	}
+	return
+}