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env.go
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env.go
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package env
import (
"fmt"
"os"
"reflect"
"strconv"
"strings"
"sync"
"time"
util "github.com/apremalal/go-util"
)
var (
_env Vars
_envLock = sync.Mutex{}
)
const (
// TagNameEnvironmentVariableName is the struct tag for what environment variable to use to populate a field.
TagNameEnvironmentVariableName = "env"
// FlagCSV is a field tag flag (say that 10 times fast).
FlagCSV = "csv"
// FlagBase64 is a field tag flag (say that 10 times fast).
FlagBase64 = "base64"
// FlagBytes is a field tag flag (say that 10 times fast).
FlagBytes = "bytes"
)
// Marshaler is a type that implements `ReadInto`.
type Marshaler interface {
MarshalEnv(vars Vars) error
}
// Env returns the current env var set.
func Env() Vars {
if _env == nil {
_envLock.Lock()
defer _envLock.Unlock()
if _env == nil {
_env = NewVarsFromEnvironment()
}
}
return _env
}
// SetEnv sets the env vars.
func SetEnv(vars Vars) {
_envLock.Lock()
_env = vars
_envLock.Unlock()
}
// Restore sets .Env() to the current os environment.
func Restore() {
SetEnv(NewVarsFromEnvironment())
}
// NewVars returns a new env var set.
func NewVars() Vars {
return Vars{}
}
// NewVarsFromEnvironment reads an EnvVar set from the environment.
func NewVarsFromEnvironment() Vars {
vars := Vars{}
envVars := os.Environ()
for _, ev := range envVars {
parts := strings.SplitN(ev, "=", 2)
if len(parts) > 1 {
vars[parts[0]] = parts[1]
}
}
return vars
}
// Vars is a set of environment variables.
type Vars map[string]string
// Set sets a value for a key.
func (ev Vars) Set(envVar, value string) {
ev[envVar] = value
}
// Restore resets an environment variable to it's environment value.
func (ev Vars) Restore(key string) {
ev[key] = os.Getenv(key)
}
// Delete removes a key from the set.
func (ev Vars) Delete(key string) {
delete(ev, key)
}
// String returns a string value for a given key, with an optional default vaule.
func (ev Vars) String(envVar string, defaults ...string) string {
if value, hasValue := ev[envVar]; hasValue {
return value
}
if len(defaults) > 0 {
return defaults[0]
}
return ""
}
// CSV returns a string array for a given string var.
func (ev Vars) CSV(envVar string, defaults ...string) []string {
if value, hasValue := ev[envVar]; hasValue && len(value) > 0 {
return strings.Split(value, ",")
}
return defaults
}
// ReadFile reads a file from the env.
func (ev Vars) ReadFile(path string) error {
return util.File.ReadByLines(path, func(line string) error {
if len(line) == 0 {
return nil
}
parts := strings.SplitN(line, "=", 2)
if len(parts) < 2 {
return nil
}
ev[parts[0]] = parts[1]
return nil
})
}
// Bool returns a boolean value for a key, defaulting to false.
// Valid "truthy" values are `true`, `yes`, and `1`.
// Everything else is false, including `REEEEEEEEEEEEEEE`.
func (ev Vars) Bool(envVar string, defaults ...bool) bool {
if value, hasValue := ev[envVar]; hasValue {
if len(value) > 0 {
return util.String.CaseInsensitiveEquals(value, "true") ||
util.String.CaseInsensitiveEquals(value, "yes") ||
util.String.CaseInsensitiveEquals(value, "enabled") ||
value == "1"
}
}
if len(defaults) > 0 {
return defaults[0]
}
return false
}
// Int returns an integer value for a given key.
func (ev Vars) Int(envVar string, defaults ...int) (int, error) {
if value, hasValue := ev[envVar]; hasValue {
return strconv.Atoi(value)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustInt returns an integer value for a given key and panics if it is malformed.
func (ev Vars) MustInt(envVar string, defaults ...int) int {
value, err := ev.Int(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Int32 returns an integer value for a given key.
func (ev Vars) Int32(envVar string, defaults ...int32) (int32, error) {
if value, hasValue := ev[envVar]; hasValue {
parsedValue, err := strconv.Atoi(value)
return int32(parsedValue), err
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustInt32 returns an integer value for a given key and panics if it is malformed.
func (ev Vars) MustInt32(envVar string, defaults ...int32) int32 {
value, err := ev.Int32(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Int64 returns an int64 value for a given key.
func (ev Vars) Int64(envVar string, defaults ...int64) (int64, error) {
if value, hasValue := ev[envVar]; hasValue {
return strconv.ParseInt(value, 10, 64)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustInt64 returns an int64 value for a given key and panics if it is malformed.
func (ev Vars) MustInt64(envVar string, defaults ...int64) int64 {
value, err := ev.Int64(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Uint32 returns an uint32 value for a given key.
func (ev Vars) Uint32(envVar string, defaults ...uint32) (uint32, error) {
if value, hasValue := ev[envVar]; hasValue {
parsedValue, err := strconv.ParseUint(value, 10, 32)
return uint32(parsedValue), err
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustUint32 returns an uint32 value for a given key and panics if it is malformed.
func (ev Vars) MustUint32(envVar string, defaults ...uint32) uint32 {
value, err := ev.Uint32(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Uint64 returns an uint64 value for a given key.
func (ev Vars) Uint64(envVar string, defaults ...uint64) (uint64, error) {
if value, hasValue := ev[envVar]; hasValue {
return strconv.ParseUint(value, 10, 64)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustUint64 returns an uint64 value for a given key and panics if it is malformed.
func (ev Vars) MustUint64(envVar string, defaults ...uint64) uint64 {
value, err := ev.Uint64(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Float64 returns an float64 value for a given key.
func (ev Vars) Float64(envVar string, defaults ...float64) (float64, error) {
if value, hasValue := ev[envVar]; hasValue {
return strconv.ParseFloat(value, 64)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustFloat64 returns an float64 value for a given key and panics if it is malformed.
func (ev Vars) MustFloat64(envVar string, defaults ...float64) float64 {
value, err := ev.Float64(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Duration returns a duration value for a given key.
func (ev Vars) Duration(envVar string, defaults ...time.Duration) (time.Duration, error) {
if value, hasValue := ev[envVar]; hasValue {
return time.ParseDuration(value)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return 0, nil
}
// MustDuration returnss a duration value for a given key and panics if malformed.
func (ev Vars) MustDuration(envVar string, defaults ...time.Duration) time.Duration {
value, err := ev.Duration(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Bytes returns a []byte value for a given key.
func (ev Vars) Bytes(envVar string, defaults ...[]byte) []byte {
if value, hasValue := ev[envVar]; hasValue && len(value) > 0 {
return []byte(value)
}
if len(defaults) > 0 {
return defaults[0]
}
return nil
}
// Base64 returns a []byte value for a given key whose value is encoded in base64.
func (ev Vars) Base64(envVar string, defaults ...[]byte) ([]byte, error) {
if value, hasValue := ev[envVar]; hasValue && len(value) > 0 {
return util.Base64.Decode(value)
}
if len(defaults) > 0 {
return defaults[0], nil
}
return nil, nil
}
// MustBase64 returns a []byte value for a given key encoded with base64, and panics if malformed.
func (ev Vars) MustBase64(envVar string, defaults ...[]byte) []byte {
value, err := ev.Base64(envVar, defaults...)
if err != nil {
panic(err)
}
return value
}
// Has returns if a key is present in the set.
func (ev Vars) Has(envVar string) bool {
_, hasKey := ev[envVar]
return hasKey
}
// HasAll returns if all of the given vars are present in the set.
func (ev Vars) HasAll(envVars ...string) bool {
if len(envVars) == 0 {
return false
}
for _, envVar := range envVars {
if !ev.Has(envVar) {
return false
}
}
return true
}
// HasAny returns if any of the given vars are present in the set.
func (ev Vars) HasAny(envVars ...string) bool {
for _, envVar := range envVars {
if ev.Has(envVar) {
return true
}
}
return false
}
// Require enforces that a given set of environment variables are present.
func (ev Vars) Require(keys ...string) error {
for _, key := range keys {
if !ev.Has(key) {
return fmt.Errorf("the following environment variables are required: `%s`", strings.Join(keys, ","))
}
}
return nil
}
// Must enforces that a given set of environment variables are present and panics
// if they're not present.
func (ev Vars) Must(keys ...string) {
for _, key := range keys {
if !ev.Has(key) {
panic(fmt.Sprintf("the following environment variables are required: `%s`", strings.Join(keys, ",")))
}
}
}
// Union returns the union of the two sets, other replacing conflicts.
func (ev Vars) Union(other Vars) Vars {
newSet := NewVars()
for key, value := range ev {
newSet[key] = value
}
for key, value := range other {
newSet[key] = value
}
return newSet
}
// Vars returns all the vars stored in the env var set.
func (ev Vars) Vars() []string {
var envVars = make([]string, len(ev))
var index int
for envVar := range ev {
envVars[index] = envVar
index++
}
return envVars
}
// Raw returns a raw KEY=VALUE form of the vars.
func (ev Vars) Raw() []string {
var raw []string
for key, value := range ev {
raw = append(raw, fmt.Sprintf("%s=%s", key, value))
}
return raw
}
// ReadInto reads the environment into tagged fields on the `obj`.
func (ev Vars) ReadInto(obj interface{}) error {
// check if the type implements marshaler.
if typed, isTyped := obj.(Marshaler); isTyped {
return typed.MarshalEnv(ev)
}
objMeta := util.Reflection.ReflectType(obj)
objValue := util.Reflection.ReflectValue(obj)
typeBool := reflect.TypeOf(false)
typeString := reflect.TypeOf("")
typeDuration := reflect.TypeOf(time.Nanosecond)
var field reflect.StructField
var tag string
var envValue interface{}
var err error
var pieces []string
var envVar string
// we need this for ... reasons.
envVars := map[string]interface{}{}
for x := 0; x < objMeta.NumField(); x++ {
field = objMeta.Field(x)
// Treat structs as nested values.
if field.Type.Kind() == reflect.Struct {
if err = ev.ReadInto(objValue.Field(x).Addr().Interface()); err != nil {
return err
}
continue
}
tag = field.Tag.Get(TagNameEnvironmentVariableName)
if len(tag) > 0 {
var csv bool
var bytes bool
var base64 bool
pieces = strings.Split(tag, ",")
envVar = pieces[0]
if len(pieces) > 1 {
for y := 1; y < len(pieces); y++ {
if pieces[y] == FlagCSV {
csv = true
} else if pieces[y] == FlagBase64 {
base64 = true
} else if pieces[y] == FlagBytes {
bytes = true
}
}
}
if csv {
envValue = ev.CSV(envVar)
} else if base64 {
envValue, err = ev.Base64(envVar)
if err != nil {
return err
}
} else if bytes {
envValue = ev.Bytes(envVar)
} else {
// infer the type.
fieldType := util.Reflection.FollowType(field.Type)
if fieldType == typeBool {
envValue = ev.Bool(envVar)
} else if fieldType == typeString {
envValue = ev.String(envVar)
} else if fieldType == typeDuration {
envValue, err = ev.Duration(envVar)
if err != nil {
return err
}
} else { // assumes a number here
envValue, err = ev.Float64(envVar)
if err != nil {
return err
}
}
}
envVars[envVar] = envValue
err = util.Reflection.SetValueByName(obj, field.Name, envVars[envVar])
if err != nil {
return err
}
}
}
return nil
}