bouncer/internal/config/environment.go

package config

import (
	"os"
	"regexp"
	"strconv"
	"time"

	"github.com/drone/envsubst"
	"github.com/pkg/errors"
	"gopkg.in/yaml.v3"
)

// var reVar = regexp.MustCompile(`^\${(\w+)}$`)
var reVar = regexp.MustCompile(`\${(.*?)}`)

type InterpolatedString string

func (is *InterpolatedString) UnmarshalYAML(value *yaml.Node) error {
	var str string

	if err := value.Decode(&str); err != nil {
		return errors.WithStack(err)
	}

	if match := reVar.FindStringSubmatch(str); len(match) > 0 {
		*is = InterpolatedString(os.Getenv(match[1]))
	} else {
		*is = InterpolatedString(str)
	}

	return nil
}

type InterpolatedInt int

func (ii *InterpolatedInt) UnmarshalYAML(value *yaml.Node) error {
	var str string

	if err := value.Decode(&str); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into string", value.Value, value.Line)
	}

	if match := reVar.FindStringSubmatch(str); len(match) > 0 {
		str = os.Getenv(match[1])
	}

	intVal, err := strconv.ParseInt(str, 10, 32)
	if err != nil {
		return errors.Wrapf(err, "could not parse int '%v',  line '%d'", str, value.Line)
	}

	*ii = InterpolatedInt(int(intVal))

	return nil
}

type InterpolatedFloat float64

func (ifl *InterpolatedFloat) UnmarshalYAML(value *yaml.Node) error {
	var str string

	if err := value.Decode(&str); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into string", value.Value, value.Line)
	}

	if match := reVar.FindStringSubmatch(str); len(match) > 0 {
		str = os.Getenv(match[1])
	}

	floatVal, err := strconv.ParseFloat(str, 10)
	if err != nil {
		return errors.Wrapf(err, "could not parse float '%v',  line '%d'", str, value.Line)
	}

	*ifl = InterpolatedFloat(floatVal)

	return nil
}

type InterpolatedBool bool

func (ib *InterpolatedBool) UnmarshalYAML(value *yaml.Node) error {
	var str string

	if err := value.Decode(&str); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into string", value.Value, value.Line)
	}

	if match := reVar.FindStringSubmatch(str); len(match) > 0 {
		str = os.Getenv(match[1])
	}

	boolVal, err := strconv.ParseBool(str)
	if err != nil {
		return errors.Wrapf(err, "could not parse bool '%v',  line '%d'", str, value.Line)
	}

	*ib = InterpolatedBool(boolVal)

	return nil
}

type InterpolatedMap struct {
	Data map[string]interface{}
	env  map[string]string
}

func (im *InterpolatedMap) UnmarshalYAML(value *yaml.Node) error {
	var data map[string]interface{}

	if err := value.Decode(&data); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into map", value.Value, value.Line)
	}

	im.Data = im.interpolateRecursive(data).(map[string]any)

	return nil
}

func (im *InterpolatedMap) interpolateRecursive(data any) any {
	if im.env == nil {
		im.env = osEnvironment()
	}

	switch typ := data.(type) {
	case map[string]any:
		for key, value := range typ {
			typ[key] = im.interpolateRecursive(value)
		}

	case string:
		if match := reVar.FindStringSubmatch(typ); len(match) > 0 {
			value, exists := im.env[match[1]]
			if !exists {
				data = ""
			}

			data = value
		}

	case []any:
		for idx := range typ {
			typ[idx] = im.interpolateRecursive(typ[idx])
		}
	}

	return data
}

func osEnvironment() map[string]string {
	environ := os.Environ()
	env := make(map[string]string, len(environ))
	for _, key := range environ {
		env[key] = os.Getenv(key)
	}
	return env
}

type InterpolatedStringSlice []string

func (iss *InterpolatedStringSlice) UnmarshalYAML(value *yaml.Node) error {
	var data []string
	var evErr error

	if err := value.Decode(&data); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into map", value.Value, value.Line)
	}

	for index, value := range data {
		//match := reVar.FindStringSubmatch(value)
		re := regexp.MustCompile(`\${(.*?)}`)

		res := re.FindAllStringSubmatch(value, 10)
		if len(res) > 0 {
			value, evErr = envsubst.EvalEnv(value)
			if evErr != nil {
				return evErr
			}
		}

		data[index] = value
	}

	*iss = data

	return nil
}

type InterpolatedDuration time.Duration

func (id *InterpolatedDuration) UnmarshalYAML(value *yaml.Node) error {
	var str string

	if err := value.Decode(&str); err != nil {
		return errors.Wrapf(err, "could not decode value '%v' (line '%d') into string", value.Value, value.Line)
	}

	if match := reVar.FindStringSubmatch(str); len(match) > 0 {
		str = os.Getenv(match[1])
	}

	duration, err := time.ParseDuration(str)
	if err != nil {
		return errors.Wrapf(err, "could not parse duration '%v',  line '%d'", str, value.Line)
	}

	*id = InterpolatedDuration(duration)

	return nil
}

func (id *InterpolatedDuration) MarshalYAML() (interface{}, error) {
	duration := time.Duration(*id)

	return duration.String(), nil
}

func NewInterpolatedDuration(d time.Duration) *InterpolatedDuration {
	id := InterpolatedDuration(d)
	return &id
}