github.com/spinnaker/spin@v1.30.0/cmd/output/output.go (about)

     1  // Copyright (c) 2018, Google, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //   http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  //   Unless required by applicable law or agreed to in writing, software
    10  //   distributed under the License is distributed on an "AS IS" BASIS,
    11  //   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  //   See the License for the specific language governing permissions and
    13  //   limitations under the License.
    14  
    15  package output
    16  
    17  import (
    18  	"bytes"
    19  	"encoding/json"
    20  	"errors"
    21  	"fmt"
    22  	"strings"
    23  
    24  	"k8s.io/client-go/util/jsonpath"
    25  	"sigs.k8s.io/yaml"
    26  )
    27  
    28  type OutputFormater func(interface{}) ([]byte, error)
    29  
    30  // ParseOutputFormat returns an OutputFormater based on the specified format.
    31  // Accepted values include 'json', 'yaml', and 'jsonpath=PATH'.
    32  // Empty string defaults to 'json'.
    33  // For more about JSONPath, see https://goessner.net/articles/JsonPath/
    34  func ParseOutputFormat(outputFormat string) (OutputFormater, error) {
    35  	switch {
    36  	case outputFormat == "" || outputFormat == "json":
    37  		return MarshalToJson, nil
    38  	case outputFormat == "yaml":
    39  		return MarshalToYaml, nil
    40  	case strings.HasPrefix(outputFormat, "jsonpath=") && outputFormat != "jsonpath=":
    41  		toks := strings.Split(outputFormat, "=")
    42  		if len(toks) != 2 {
    43  			return nil, errors.New(fmt.Sprintf("Failed to parse output format flag value: %s", outputFormat))
    44  		}
    45  		return MarshalToJsonPathWrapper(toks[1]), nil
    46  	default:
    47  		return nil, errors.New(fmt.Sprintf("Failed to parse output format flag value: %s", outputFormat))
    48  	}
    49  }
    50  
    51  func MarshalToJson(input interface{}) ([]byte, error) {
    52  	pretty, err := json.MarshalIndent(input, "", " ")
    53  	if err != nil {
    54  		return nil, fmt.Errorf("Failed to marshal to json: %v", err)
    55  	}
    56  	return pretty, nil
    57  }
    58  
    59  // MarshalToJsonPathWrapper returns a MarshalToJsonPath function that uses the
    60  // specified jsonpath expression.
    61  // This leverages the kubernetes jsonpath library
    62  // (https://kubernetes.io/docs/reference/kubectl/jsonpath/).
    63  func MarshalToJsonPathWrapper(expression string) OutputFormater {
    64  	expr := expression
    65  	// aka MarshalToJsonPath
    66  	return func(input interface{}) ([]byte, error) {
    67  		jp := jsonpath.New("json-path")
    68  
    69  		if err := jp.Parse(expr); err != nil {
    70  			return nil, fmt.Errorf("Failed to parse jsonpath expression: %v", err)
    71  		}
    72  
    73  		values, err := jp.FindResults(input)
    74  		if err != nil {
    75  			return nil, fmt.Errorf("Failed to execute jsonpath %s on input %s: %v ", expr, input, err)
    76  		}
    77  
    78  		if values == nil || len(values) == 0 || len(values[0]) == 0 {
    79  			return nil, errors.New(fmt.Sprintf("Error parsing value from input %v using template %s: %v ", input, expr, err))
    80  		}
    81  
    82  		json, err := MarshalToJson(values[0][0].Interface())
    83  		if err != nil {
    84  			return nil, err
    85  		}
    86  		return unquote(json), err
    87  	}
    88  }
    89  
    90  func MarshalToYaml(input interface{}) ([]byte, error) {
    91  	pretty, err := yaml.Marshal(input)
    92  	if err != nil {
    93  		return nil, fmt.Errorf("Failed to marshal to yaml: %v", err)
    94  	}
    95  	return pretty, nil
    96  }
    97  
    98  func unquote(input []byte) []byte {
    99  	input = bytes.TrimLeft(input, "\"")
   100  	input = bytes.TrimRight(input, "\"")
   101  	return input
   102  }