shortcut.go

Documentation: k8s.io/client-go/restmapper

     1  /*
     2  Copyright 2016 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 restmapper
    18  
    19  import (
    20  	"fmt"
    21  	"strings"
    22  
    23  	"k8s.io/klog/v2"
    24  
    25  	"k8s.io/apimachinery/pkg/api/meta"
    26  	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    27  	"k8s.io/apimachinery/pkg/runtime/schema"
    28  	"k8s.io/client-go/discovery"
    29  )
    30  
    31  // shortcutExpander is a RESTMapper that can be used for Kubernetes resources.   It expands the resource first, then invokes the wrapped
    32  type shortcutExpander struct {
    33  	RESTMapper meta.RESTMapper
    34  
    35  	discoveryClient discovery.DiscoveryInterface
    36  
    37  	warningHandler func(string)
    38  }
    39  
    40  var _ meta.ResettableRESTMapper = shortcutExpander{}
    41  
    42  // NewShortcutExpander wraps a restmapper in a layer that expands shortcuts found via discovery
    43  func NewShortcutExpander(delegate meta.RESTMapper, client discovery.DiscoveryInterface, warningHandler func(string)) meta.RESTMapper {
    44  	return shortcutExpander{RESTMapper: delegate, discoveryClient: client, warningHandler: warningHandler}
    45  }
    46  
    47  // KindFor fulfills meta.RESTMapper
    48  func (e shortcutExpander) KindFor(resource schema.GroupVersionResource) (schema.GroupVersionKind, error) {
    49  	// expandResourceShortcut works with current API resources as read from discovery cache.
    50  	// In case of new CRDs this means we potentially don't have current state of discovery.
    51  	// In the current wiring in k8s.io/cli-runtime/pkg/genericclioptions/config_flags.go#toRESTMapper,
    52  	// we are using DeferredDiscoveryRESTMapper which on KindFor failure will clear the
    53  	// cache and fetch all data from a cluster (see k8s.io/client-go/restmapper/discovery.go#KindFor).
    54  	// Thus another call to expandResourceShortcut, after a NoMatchError should successfully
    55  	// read Kind to the user or an error.
    56  	gvk, err := e.RESTMapper.KindFor(e.expandResourceShortcut(resource))
    57  	if meta.IsNoMatchError(err) {
    58  		return e.RESTMapper.KindFor(e.expandResourceShortcut(resource))
    59  	}
    60  	return gvk, err
    61  }
    62  
    63  // KindsFor fulfills meta.RESTMapper
    64  func (e shortcutExpander) KindsFor(resource schema.GroupVersionResource) ([]schema.GroupVersionKind, error) {
    65  	return e.RESTMapper.KindsFor(e.expandResourceShortcut(resource))
    66  }
    67  
    68  // ResourcesFor fulfills meta.RESTMapper
    69  func (e shortcutExpander) ResourcesFor(resource schema.GroupVersionResource) ([]schema.GroupVersionResource, error) {
    70  	return e.RESTMapper.ResourcesFor(e.expandResourceShortcut(resource))
    71  }
    72  
    73  // ResourceFor fulfills meta.RESTMapper
    74  func (e shortcutExpander) ResourceFor(resource schema.GroupVersionResource) (schema.GroupVersionResource, error) {
    75  	return e.RESTMapper.ResourceFor(e.expandResourceShortcut(resource))
    76  }
    77  
    78  // ResourceSingularizer fulfills meta.RESTMapper
    79  func (e shortcutExpander) ResourceSingularizer(resource string) (string, error) {
    80  	return e.RESTMapper.ResourceSingularizer(e.expandResourceShortcut(schema.GroupVersionResource{Resource: resource}).Resource)
    81  }
    82  
    83  // RESTMapping fulfills meta.RESTMapper
    84  func (e shortcutExpander) RESTMapping(gk schema.GroupKind, versions ...string) (*meta.RESTMapping, error) {
    85  	return e.RESTMapper.RESTMapping(gk, versions...)
    86  }
    87  
    88  // RESTMappings fulfills meta.RESTMapper
    89  func (e shortcutExpander) RESTMappings(gk schema.GroupKind, versions ...string) ([]*meta.RESTMapping, error) {
    90  	return e.RESTMapper.RESTMappings(gk, versions...)
    91  }
    92  
    93  // getShortcutMappings returns a set of tuples which holds short names for resources.
    94  // First the list of potential resources will be taken from the API server.
    95  // Next we will append the hardcoded list of resources - to be backward compatible with old servers.
    96  // NOTE that the list is ordered by group priority.
    97  func (e shortcutExpander) getShortcutMappings() ([]*metav1.APIResourceList, []resourceShortcuts, error) {
    98  	res := []resourceShortcuts{}
    99  	// get server resources
   100  	// This can return an error *and* the results it was able to find.  We don't need to fail on the error.
   101  	_, apiResList, err := e.discoveryClient.ServerGroupsAndResources()
   102  	if err != nil {
   103  		klog.V(1).Infof("Error loading discovery information: %v", err)
   104  	}
   105  	for _, apiResources := range apiResList {
   106  		gv, err := schema.ParseGroupVersion(apiResources.GroupVersion)
   107  		if err != nil {
   108  			klog.V(1).Infof("Unable to parse groupversion = %s due to = %s", apiResources.GroupVersion, err.Error())
   109  			continue
   110  		}
   111  		for _, apiRes := range apiResources.APIResources {
   112  			for _, shortName := range apiRes.ShortNames {
   113  				rs := resourceShortcuts{
   114  					ShortForm: schema.GroupResource{Group: gv.Group, Resource: shortName},
   115  					LongForm:  schema.GroupResource{Group: gv.Group, Resource: apiRes.Name},
   116  				}
   117  				res = append(res, rs)
   118  			}
   119  		}
   120  	}
   121  
   122  	return apiResList, res, nil
   123  }
   124  
   125  // expandResourceShortcut will return the expanded version of resource
   126  // (something that a pkg/api/meta.RESTMapper can understand), if it is
   127  // indeed a shortcut. If no match has been found, we will match on group prefixing.
   128  // Lastly we will return resource unmodified.
   129  func (e shortcutExpander) expandResourceShortcut(resource schema.GroupVersionResource) schema.GroupVersionResource {
   130  	// get the shortcut mappings and return on first match.
   131  	if allResources, shortcutResources, err := e.getShortcutMappings(); err == nil {
   132  		// avoid expanding if there's an exact match to a full resource name
   133  		for _, apiResources := range allResources {
   134  			gv, err := schema.ParseGroupVersion(apiResources.GroupVersion)
   135  			if err != nil {
   136  				continue
   137  			}
   138  			if len(resource.Group) != 0 && resource.Group != gv.Group {
   139  				continue
   140  			}
   141  			for _, apiRes := range apiResources.APIResources {
   142  				if resource.Resource == apiRes.Name {
   143  					return resource
   144  				}
   145  				if resource.Resource == apiRes.SingularName {
   146  					return resource
   147  				}
   148  			}
   149  		}
   150  
   151  		found := false
   152  		var rsc schema.GroupVersionResource
   153  		warnedAmbiguousShortcut := make(map[schema.GroupResource]bool)
   154  		for _, item := range shortcutResources {
   155  			if len(resource.Group) != 0 && resource.Group != item.ShortForm.Group {
   156  				continue
   157  			}
   158  			if resource.Resource == item.ShortForm.Resource {
   159  				if found {
   160  					if item.LongForm.Group == rsc.Group && item.LongForm.Resource == rsc.Resource {
   161  						// It is common and acceptable that group/resource has multiple
   162  						// versions registered in cluster. This does not introduce ambiguity
   163  						// in terms of shortname usage.
   164  						continue
   165  					}
   166  					if !warnedAmbiguousShortcut[item.LongForm] {
   167  						if e.warningHandler != nil {
   168  							e.warningHandler(fmt.Sprintf("short name %q could also match lower priority resource %s", resource.Resource, item.LongForm.String()))
   169  						}
   170  						warnedAmbiguousShortcut[item.LongForm] = true
   171  					}
   172  					continue
   173  				}
   174  				rsc.Resource = item.LongForm.Resource
   175  				rsc.Group = item.LongForm.Group
   176  				found = true
   177  			}
   178  		}
   179  		if found {
   180  			return rsc
   181  		}
   182  
   183  		// we didn't find exact match so match on group prefixing. This allows autoscal to match autoscaling
   184  		if len(resource.Group) == 0 {
   185  			return resource
   186  		}
   187  		for _, item := range shortcutResources {
   188  			if !strings.HasPrefix(item.ShortForm.Group, resource.Group) {
   189  				continue
   190  			}
   191  			if resource.Resource == item.ShortForm.Resource {
   192  				resource.Resource = item.LongForm.Resource
   193  				resource.Group = item.LongForm.Group
   194  				return resource
   195  			}
   196  		}
   197  	}
   198  
   199  	return resource
   200  }
   201  
   202  func (e shortcutExpander) Reset() {
   203  	meta.MaybeResetRESTMapper(e.RESTMapper)
   204  }
   205  
   206  // ResourceShortcuts represents a structure that holds the information how to
   207  // transition from resource's shortcut to its full name.
   208  type resourceShortcuts struct {
   209  	ShortForm schema.GroupResource
   210  	LongForm  schema.GroupResource
   211  }
   212
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