env_file.go

Documentation: k8s.io/kubectl/pkg/cmd/util

     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 util
    18  
    19  import (
    20  	"bufio"
    21  	"bytes"
    22  	"fmt"
    23  	"os"
    24  	"strings"
    25  	"unicode"
    26  	"unicode/utf8"
    27  
    28  	"k8s.io/apimachinery/pkg/util/validation"
    29  )
    30  
    31  var utf8bom = []byte{0xEF, 0xBB, 0xBF}
    32  
    33  // processEnvFileLine returns a blank key if the line is empty or a comment.
    34  // The value will be retrieved from the environment if necessary.
    35  func processEnvFileLine(line []byte, filePath string,
    36  	currentLine int) (key, value string, err error) {
    37  
    38  	if !utf8.Valid(line) {
    39  		return ``, ``, fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v",
    40  			filePath, currentLine+1, line)
    41  	}
    42  
    43  	// We trim UTF8 BOM from the first line of the file but no others
    44  	if currentLine == 0 {
    45  		line = bytes.TrimPrefix(line, utf8bom)
    46  	}
    47  
    48  	// trim the line from all leading whitespace first
    49  	line = bytes.TrimLeftFunc(line, unicode.IsSpace)
    50  
    51  	// If the line is empty or a comment, we return a blank key/value pair.
    52  	if len(line) == 0 || line[0] == '#' {
    53  		return ``, ``, nil
    54  	}
    55  
    56  	data := strings.SplitN(string(line), "=", 2)
    57  	key = data[0]
    58  	if errs := validation.IsEnvVarName(key); len(errs) != 0 {
    59  		return ``, ``, fmt.Errorf("%q is not a valid key name: %s", key, strings.Join(errs, ";"))
    60  	}
    61  
    62  	if len(data) == 2 {
    63  		value = data[1]
    64  	} else {
    65  		// No value (no `=` in the line) is a signal to obtain the value
    66  		// from the environment.
    67  		value = os.Getenv(key)
    68  	}
    69  	return
    70  }
    71  
    72  // AddFromEnvFile processes an env file allows a generic addTo to handle the
    73  // collection of key value pairs or returns an error.
    74  func AddFromEnvFile(filePath string, addTo func(key, value string) error) error {
    75  	f, err := os.Open(filePath)
    76  	if err != nil {
    77  		return err
    78  	}
    79  	defer f.Close()
    80  
    81  	scanner := bufio.NewScanner(f)
    82  	currentLine := 0
    83  	for scanner.Scan() {
    84  		// Process the current line, retrieving a key/value pair if
    85  		// possible.
    86  		scannedBytes := scanner.Bytes()
    87  		key, value, err := processEnvFileLine(scannedBytes, filePath, currentLine)
    88  		if err != nil {
    89  			return err
    90  		}
    91  		currentLine++
    92  
    93  		if len(key) == 0 {
    94  			// no key means line was empty or a comment
    95  			continue
    96  		}
    97  
    98  		if err = addTo(key, value); err != nil {
    99  			return err
   100  		}
   101  	}
   102  	return nil
   103  }
   104
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