name.go

Documentation: k8s.io/cli-runtime/pkg/printers

     1  /*
     2  Copyright 2017 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package printers
    18  
    19  import (
    20  	"fmt"
    21  	"io"
    22  	"reflect"
    23  	"strings"
    24  
    25  	"k8s.io/apimachinery/pkg/api/meta"
    26  	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    27  	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
    28  	"k8s.io/apimachinery/pkg/runtime"
    29  	"k8s.io/apimachinery/pkg/runtime/schema"
    30  )
    31  
    32  // NamePrinter is an implementation of ResourcePrinter which outputs "resource/name" pair of an object.
    33  type NamePrinter struct {
    34  	// ShortOutput indicates whether an operation should be
    35  	// printed along side the "resource/name" pair for an object.
    36  	ShortOutput bool
    37  	// Operation describes the name of the action that
    38  	// took place on an object, to be included in the
    39  	// finalized "successful" message.
    40  	Operation string
    41  }
    42  
    43  // PrintObj is an implementation of ResourcePrinter.PrintObj which decodes the object
    44  // and print "resource/name" pair. If the object is a List, print all items in it.
    45  func (p *NamePrinter) PrintObj(obj runtime.Object, w io.Writer) error {
    46  	switch castObj := obj.(type) {
    47  	case *metav1.WatchEvent:
    48  		obj = castObj.Object.Object
    49  	}
    50  
    51  	// we use reflect.Indirect here in order to obtain the actual value from a pointer.
    52  	// using reflect.Indirect indiscriminately is valid here, as all runtime.Objects are supposed to be pointers.
    53  	// we need an actual value in order to retrieve the package path for an object.
    54  	if InternalObjectPreventer.IsForbidden(reflect.Indirect(reflect.ValueOf(obj)).Type().PkgPath()) {
    55  		return fmt.Errorf(InternalObjectPrinterErr)
    56  	}
    57  
    58  	if meta.IsListType(obj) {
    59  		// we allow unstructured lists for now because they always contain the GVK information.  We should chase down
    60  		// callers and stop them from passing unflattened lists
    61  		// TODO chase the caller that is setting this and remove it.
    62  		if _, ok := obj.(*unstructured.UnstructuredList); !ok {
    63  			return fmt.Errorf("list types are not supported by name printing: %T", obj)
    64  		}
    65  
    66  		items, err := meta.ExtractList(obj)
    67  		if err != nil {
    68  			return err
    69  		}
    70  		for _, obj := range items {
    71  			if err := p.PrintObj(obj, w); err != nil {
    72  				return err
    73  			}
    74  		}
    75  		return nil
    76  	}
    77  
    78  	if obj.GetObjectKind().GroupVersionKind().Empty() {
    79  		return fmt.Errorf("missing apiVersion or kind; try GetObjectKind().SetGroupVersionKind() if you know the type")
    80  	}
    81  
    82  	name := "<unknown>"
    83  	if acc, err := meta.Accessor(obj); err == nil {
    84  		if n := acc.GetName(); len(n) > 0 {
    85  			name = n
    86  		}
    87  	}
    88  
    89  	return printObj(w, name, p.Operation, p.ShortOutput, GetObjectGroupKind(obj))
    90  }
    91  
    92  func GetObjectGroupKind(obj runtime.Object) schema.GroupKind {
    93  	if obj == nil {
    94  		return schema.GroupKind{Kind: "<unknown>"}
    95  	}
    96  	groupVersionKind := obj.GetObjectKind().GroupVersionKind()
    97  	if len(groupVersionKind.Kind) > 0 {
    98  		return groupVersionKind.GroupKind()
    99  	}
   100  
   101  	if uns, ok := obj.(*unstructured.Unstructured); ok {
   102  		if len(uns.GroupVersionKind().Kind) > 0 {
   103  			return uns.GroupVersionKind().GroupKind()
   104  		}
   105  	}
   106  
   107  	return schema.GroupKind{Kind: "<unknown>"}
   108  }
   109  
   110  func printObj(w io.Writer, name string, operation string, shortOutput bool, groupKind schema.GroupKind) error {
   111  	if len(groupKind.Kind) == 0 {
   112  		return fmt.Errorf("missing kind for resource with name %v", name)
   113  	}
   114  
   115  	if len(operation) > 0 {
   116  		operation = " " + operation
   117  	}
   118  
   119  	if shortOutput {
   120  		operation = ""
   121  	}
   122  
   123  	if len(groupKind.Group) == 0 {
   124  		fmt.Fprintf(w, "%s/%s%s\n", strings.ToLower(groupKind.Kind), name, operation)
   125  		return nil
   126  	}
   127  
   128  	fmt.Fprintf(w, "%s.%s/%s%s\n", strings.ToLower(groupKind.Kind), groupKind.Group, name, operation)
   129  	return nil
   130  }
   131
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