handle environment variable for yaml file

[bthuillier]

No description provided.

[99-not-out]

This is a great addition! 👍

[qboileau]

@bthuillier @99-not-out
If you want here is an implementation that still panic when missing env var in a "strict mode" and replace with empty value in a "non strict mode"
It also accumulates missing env to panic with all of them in the error message

import (
	"fmt"
	"os"
	"regexp"
	"strings"
)

var envVarRegex = regexp.MustCompile(`\$\{([^}]+)\}`)

func expandEnvVars(input []byte, strict bool) []byte {
	missingEnvVars := make([]string, 0)
	result := envVarRegex.ReplaceAllFunc(input, func(match []byte) []byte {
		varName := string(match[2 : len(match)-1])
		defaultValue := ""
		if strings.Contains(varName, ":-") {
			parts := strings.SplitN(varName, ":-", 2)
			varName = parts[0]
			defaultValue = parts[1]
		}
		value, isFound := os.LookupEnv(varName)

		// use default value
		if (!isFound || value == "") && defaultValue != "" {
			return []byte(defaultValue)
		}

		if strict {
			if (!isFound || value == "") && defaultValue == "" {
				missingEnvVars = append(missingEnvVars, varName)
				return []byte("")
			}
		} else {
			if !isFound && defaultValue == "" {
				missingEnvVars = append(missingEnvVars, varName)
				return []byte("")
			}
		}
	        return []byte(value)
	})
	if len(missingEnvVars) > 0 {
		panic(fmt.Sprintf("Missing environment variables: %s", strings.Join(missingEnvVars, ", ")))
	}
	return result
}

The strict mode could be a CLI flag with by default is strict and be disabled with a --permissive flag or something

WDYT ?

[bthuillier]

I love it ❤️

[jheerman]

Somehow I slept on this new feature. Amazing and very much appreciated!