explain.go

Documentation: k8s.io/kubectl/pkg/explain

     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 explain
    18  
    19  import (
    20  	"fmt"
    21  	"io"
    22  	"strings"
    23  
    24  	"k8s.io/apimachinery/pkg/api/meta"
    25  	"k8s.io/apimachinery/pkg/runtime/schema"
    26  	"k8s.io/client-go/util/jsonpath"
    27  	"k8s.io/kube-openapi/pkg/util/proto"
    28  )
    29  
    30  type fieldsPrinter interface {
    31  	PrintFields(proto.Schema) error
    32  }
    33  
    34  // jsonPathParse gets back the inner list of nodes we want to work with
    35  func jsonPathParse(in string) ([]jsonpath.Node, error) {
    36  	// Remove trailing period just in case
    37  	in = strings.TrimSuffix(in, ".")
    38  
    39  	// Define initial jsonpath Parser
    40  	jpp, err := jsonpath.Parse("user", "{."+in+"}")
    41  	if err != nil {
    42  		return nil, err
    43  	}
    44  
    45  	// Because of the way the jsonpath library works, the schema of the parser is [][]NodeList
    46  	// meaning we need to get the outer node list, make sure it's only length 1, then get the inner node
    47  	// list, and only then can we look at the individual nodes themselves.
    48  	outerNodeList := jpp.Root.Nodes
    49  	if len(outerNodeList) != 1 {
    50  		return nil, fmt.Errorf("must pass in 1 jsonpath string")
    51  	}
    52  
    53  	// The root node is always a list node so this type assertion is safe
    54  	return outerNodeList[0].(*jsonpath.ListNode).Nodes, nil
    55  }
    56  
    57  // SplitAndParseResourceRequest separates the users input into a model and fields
    58  func SplitAndParseResourceRequest(inResource string, mapper meta.RESTMapper) (schema.GroupVersionResource, []string, error) {
    59  	inResourceNodeList, err := jsonPathParse(inResource)
    60  	if err != nil {
    61  		return schema.GroupVersionResource{}, nil, err
    62  	}
    63  
    64  	if inResourceNodeList[0].Type() != jsonpath.NodeField {
    65  		return schema.GroupVersionResource{}, nil, fmt.Errorf("invalid jsonpath syntax, first node must be field node")
    66  	}
    67  	resource := inResourceNodeList[0].(*jsonpath.FieldNode).Value
    68  	gvr, err := mapper.ResourceFor(schema.GroupVersionResource{Resource: resource})
    69  	if err != nil {
    70  		return schema.GroupVersionResource{}, nil, err
    71  	}
    72  
    73  	var fieldsPath []string
    74  	for _, node := range inResourceNodeList[1:] {
    75  		if node.Type() != jsonpath.NodeField {
    76  			return schema.GroupVersionResource{}, nil, fmt.Errorf("invalid jsonpath syntax, all nodes must be field nodes")
    77  		}
    78  		fieldsPath = append(fieldsPath, node.(*jsonpath.FieldNode).Value)
    79  	}
    80  
    81  	return gvr, fieldsPath, nil
    82  }
    83  
    84  // SplitAndParseResourceRequestWithMatchingPrefix separates the users input into a model and fields
    85  // while selecting gvr whose (resource, group) prefix matches the resource
    86  func SplitAndParseResourceRequestWithMatchingPrefix(inResource string, mapper meta.RESTMapper) (gvr schema.GroupVersionResource, fieldsPath []string, err error) {
    87  	inResourceNodeList, err := jsonPathParse(inResource)
    88  	if err != nil {
    89  		return schema.GroupVersionResource{}, nil, err
    90  	}
    91  
    92  	// Get resource from first node of jsonpath
    93  	if inResourceNodeList[0].Type() != jsonpath.NodeField {
    94  		return schema.GroupVersionResource{}, nil, fmt.Errorf("invalid jsonpath syntax, first node must be field node")
    95  	}
    96  	resource := inResourceNodeList[0].(*jsonpath.FieldNode).Value
    97  
    98  	gvrs, err := mapper.ResourcesFor(schema.GroupVersionResource{Resource: resource})
    99  	if err != nil {
   100  		return schema.GroupVersionResource{}, nil, err
   101  	}
   102  
   103  	for _, gvrItem := range gvrs {
   104  		// Find first gvr whose gr prefixes requested resource
   105  		groupResource := gvrItem.GroupResource().String()
   106  		if strings.HasPrefix(inResource, groupResource) {
   107  			resourceSuffix := inResource[len(groupResource):]
   108  			var fieldsPath []string
   109  			if len(resourceSuffix) > 0 {
   110  				// Define another jsonpath Parser for the resource suffix
   111  				resourceSuffixNodeList, err := jsonPathParse(resourceSuffix)
   112  				if err != nil {
   113  					return schema.GroupVersionResource{}, nil, err
   114  				}
   115  
   116  				if len(resourceSuffixNodeList) > 0 {
   117  					nodeList := resourceSuffixNodeList[1:]
   118  					for _, node := range nodeList {
   119  						if node.Type() != jsonpath.NodeField {
   120  							return schema.GroupVersionResource{}, nil, fmt.Errorf("invalid jsonpath syntax, first node must be field node")
   121  						}
   122  						fieldsPath = append(fieldsPath, node.(*jsonpath.FieldNode).Value)
   123  					}
   124  				}
   125  			}
   126  			return gvrItem, fieldsPath, nil
   127  		}
   128  	}
   129  
   130  	// If no match, take the first (the highest priority) gvr
   131  	fieldsPath = []string{}
   132  	if len(gvrs) > 0 {
   133  		gvr = gvrs[0]
   134  
   135  		fieldsPathNodeList, err := jsonPathParse(inResource)
   136  		if err != nil {
   137  			return schema.GroupVersionResource{}, nil, err
   138  		}
   139  
   140  		for _, node := range fieldsPathNodeList[1:] {
   141  			if node.Type() != jsonpath.NodeField {
   142  				return schema.GroupVersionResource{}, nil, fmt.Errorf("invalid jsonpath syntax, first node must be field node")
   143  			}
   144  			fieldsPath = append(fieldsPath, node.(*jsonpath.FieldNode).Value)
   145  		}
   146  	}
   147  
   148  	return gvr, fieldsPath, nil
   149  }
   150  
   151  // PrintModelDescription prints the description of a specific model or dot path.
   152  // If recursive, all components nested within the fields of the schema will be
   153  // printed.
   154  func PrintModelDescription(fieldsPath []string, w io.Writer, schema proto.Schema, gvk schema.GroupVersionKind, recursive bool) error {
   155  	fieldName := ""
   156  	if len(fieldsPath) != 0 {
   157  		fieldName = fieldsPath[len(fieldsPath)-1]
   158  	}
   159  
   160  	// Go down the fieldsPath to find what we're trying to explain
   161  	schema, err := LookupSchemaForField(schema, fieldsPath)
   162  	if err != nil {
   163  		return err
   164  	}
   165  	b := fieldsPrinterBuilder{Recursive: recursive}
   166  	f := &Formatter{Writer: w, Wrap: 80}
   167  	return PrintModel(fieldName, f, b, schema, gvk)
   168  }
   169
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