apiserver: add warnings for deprecated APIs

Author: liggitt

staging/src/k8s.io/apiserver/pkg/endpoints/deprecation/deprecation.go

@@ -0,0 +1,133 @@
+/*
+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 deprecation
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/version"
+)
+
+type apiLifecycleDeprecated interface {
+	APILifecycleDeprecated() (major, minor int)
+}
+
+type apiLifecycleRemoved interface {
+	APILifecycleRemoved() (major, minor int)
+}
+
+type apiLifecycleReplacement interface {
+	APILifecycleReplacement() schema.GroupVersionKind
+}
+
+// extract all digits at the beginning of the string
+var leadingDigits = regexp.MustCompile(`^(\d+)`)
+
+// MajorMinor parses a numeric major/minor version from the provided version info.
+// The minor version drops all characters after the first non-digit character:
+//   version.Info{Major:"1", Minor:"2+"} -> 1,2
+//   version.Info{Major:"1", Minor:"2.3-build4"} -> 1,2
+func MajorMinor(v version.Info) (int, int, error) {
+	major, err := strconv.Atoi(v.Major)
+	if err != nil {
+		return 0, 0, err
+	}
+	minor, err := strconv.Atoi(leadingDigits.FindString(v.Minor))
+	if err != nil {
+		return 0, 0, err
+	}
+	return major, minor, nil
+}
+
+// IsDeprecated returns true if obj implements APILifecycleDeprecated() and returns
+// a major/minor version that is non-zero and is <= the specified current major/minor version.
+func IsDeprecated(obj runtime.Object, currentMajor, currentMinor int) bool {
+	deprecated, isDeprecated := obj.(apiLifecycleDeprecated)
+	if !isDeprecated {
+		return false
+	}
+
+	deprecatedMajor, deprecatedMinor := deprecated.APILifecycleDeprecated()
+	// no deprecation version expressed
+	if deprecatedMajor == 0 && deprecatedMinor == 0 {
+		return false
+	}
+	// no current version info available
+	if currentMajor == 0 && currentMinor == 0 {
+		return true
+	}
+	// compare deprecation version to current version
+	if deprecatedMajor > currentMajor {
+		return false
+	}
+	if deprecatedMajor == currentMajor && deprecatedMinor > currentMinor {
+		return false
+	}
+	return true
+}
+
+// RemovedRelease returns the major/minor version in which the given object is unavailable (in the form "<major>.<minor>")
+// if the object implements APILifecycleRemoved() to indicate a non-zero removal version, and returns an empty string otherwise.
+func RemovedRelease(obj runtime.Object) string {
+	if removed, hasRemovalInfo := obj.(apiLifecycleRemoved); hasRemovalInfo {
+		removedMajor, removedMinor := removed.APILifecycleRemoved()
+		if removedMajor != 0 || removedMinor != 0 {
+			return fmt.Sprintf("%d.%d", removedMajor, removedMinor)
+		}
+	}
+	return ""
+}
+
+// WarningMessage returns a human-readable deprecation warning if the object implements APILifecycleDeprecated()
+// to indicate a non-zero deprecated major/minor version and has a populated GetObjectKind().GroupVersionKind().
+func WarningMessage(obj runtime.Object) string {
+	deprecated, isDeprecated := obj.(apiLifecycleDeprecated)
+	if !isDeprecated {
+		return ""
+	}
+
+	deprecatedMajor, deprecatedMinor := deprecated.APILifecycleDeprecated()
+	if deprecatedMajor == 0 && deprecatedMinor == 0 {
+		return ""
+	}
+
+	gvk := obj.GetObjectKind().GroupVersionKind()
+	if gvk.Empty() {
+		return ""
+	}
+	deprecationWarning := fmt.Sprintf("%s %s is deprecated in v%d.%d+", gvk.GroupVersion().String(), gvk.Kind, deprecatedMajor, deprecatedMinor)
+
+	if removed, hasRemovalInfo := obj.(apiLifecycleRemoved); hasRemovalInfo {
+		removedMajor, removedMinor := removed.APILifecycleRemoved()
+		if removedMajor != 0 || removedMinor != 0 {
+			deprecationWarning = deprecationWarning + fmt.Sprintf(", unavailable in v%d.%d+", removedMajor, removedMinor)
+		}
+	}
+
+	if replaced, hasReplacement := obj.(apiLifecycleReplacement); hasReplacement {
+		replacement := replaced.APILifecycleReplacement()
+		if !replacement.Empty() {
+			deprecationWarning = deprecationWarning + fmt.Sprintf("; use %s %s", replacement.GroupVersion().String(), replacement.Kind)
+		}
+	}
+
+	return deprecationWarning
+}