521 lines
12 KiB
Go
521 lines
12 KiB
Go
package env
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import (
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"encoding"
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"fmt"
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"net/url"
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"os"
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"reflect"
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"strconv"
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"strings"
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"time"
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"unicode"
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)
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// nolint: gochecknoglobals
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var (
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defaultBuiltInParsers = map[reflect.Kind]ParserFunc{
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reflect.Bool: func(v string) (interface{}, error) {
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return strconv.ParseBool(v)
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},
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reflect.String: func(v string) (interface{}, error) {
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return v, nil
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},
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reflect.Int: func(v string) (interface{}, error) {
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i, err := strconv.ParseInt(v, 10, 32)
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return int(i), err
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},
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reflect.Int16: func(v string) (interface{}, error) {
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i, err := strconv.ParseInt(v, 10, 16)
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return int16(i), err
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},
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reflect.Int32: func(v string) (interface{}, error) {
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i, err := strconv.ParseInt(v, 10, 32)
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return int32(i), err
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},
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reflect.Int64: func(v string) (interface{}, error) {
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return strconv.ParseInt(v, 10, 64)
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},
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reflect.Int8: func(v string) (interface{}, error) {
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i, err := strconv.ParseInt(v, 10, 8)
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return int8(i), err
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},
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reflect.Uint: func(v string) (interface{}, error) {
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i, err := strconv.ParseUint(v, 10, 32)
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return uint(i), err
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},
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reflect.Uint16: func(v string) (interface{}, error) {
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i, err := strconv.ParseUint(v, 10, 16)
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return uint16(i), err
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},
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reflect.Uint32: func(v string) (interface{}, error) {
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i, err := strconv.ParseUint(v, 10, 32)
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return uint32(i), err
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},
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reflect.Uint64: func(v string) (interface{}, error) {
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i, err := strconv.ParseUint(v, 10, 64)
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return i, err
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},
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reflect.Uint8: func(v string) (interface{}, error) {
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i, err := strconv.ParseUint(v, 10, 8)
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return uint8(i), err
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},
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reflect.Float64: func(v string) (interface{}, error) {
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return strconv.ParseFloat(v, 64)
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},
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reflect.Float32: func(v string) (interface{}, error) {
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f, err := strconv.ParseFloat(v, 32)
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return float32(f), err
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},
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}
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)
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func defaultTypeParsers() map[reflect.Type]ParserFunc {
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return map[reflect.Type]ParserFunc{
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reflect.TypeOf(url.URL{}): func(v string) (interface{}, error) {
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u, err := url.Parse(v)
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if err != nil {
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return nil, newParseValueError("unable to parse URL", err)
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}
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return *u, nil
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},
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reflect.TypeOf(time.Nanosecond): func(v string) (interface{}, error) {
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s, err := time.ParseDuration(v)
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if err != nil {
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return nil, newParseValueError("unable to parse duration", err)
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}
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return s, err
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},
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}
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}
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// ParserFunc defines the signature of a function that can be used within `CustomParsers`.
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type ParserFunc func(v string) (interface{}, error)
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// OnSetFn is a hook that can be run when a value is set.
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type OnSetFn func(tag string, value interface{}, isDefault bool)
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// Options for the parser.
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type Options struct {
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// Environment keys and values that will be accessible for the service.
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Environment map[string]string
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// TagName specifies another tagname to use rather than the default env.
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TagName string
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// RequiredIfNoDef automatically sets all env as required if they do not
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// declare 'envDefault'.
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RequiredIfNoDef bool
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// OnSet allows to run a function when a value is set.
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OnSet OnSetFn
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// Prefix define a prefix for each key.
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Prefix string
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// UseFieldNameByDefault defines whether or not env should use the field
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// name by default if the `env` key is missing.
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UseFieldNameByDefault bool
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// Custom parse functions for different types.
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FuncMap map[reflect.Type]ParserFunc
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}
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func defaultOptions() Options {
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return Options{
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TagName: "env",
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Environment: toMap(os.Environ()),
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FuncMap: defaultTypeParsers(),
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}
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}
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func customOptions(opt Options) Options {
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defOpts := defaultOptions()
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if opt.TagName == "" {
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opt.TagName = defOpts.TagName
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}
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if opt.Environment == nil {
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opt.Environment = defOpts.Environment
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}
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if opt.FuncMap == nil {
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opt.FuncMap = map[reflect.Type]ParserFunc{}
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}
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for k, v := range defOpts.FuncMap {
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opt.FuncMap[k] = v
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}
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return opt
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}
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func optionsWithEnvPrefix(field reflect.StructField, opts Options) Options {
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return Options{
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Environment: opts.Environment,
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TagName: opts.TagName,
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RequiredIfNoDef: opts.RequiredIfNoDef,
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OnSet: opts.OnSet,
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Prefix: opts.Prefix + field.Tag.Get("envPrefix"),
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UseFieldNameByDefault: opts.UseFieldNameByDefault,
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FuncMap: opts.FuncMap,
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}
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}
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// Parse parses a struct containing `env` tags and loads its values from
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// environment variables.
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func Parse(v interface{}) error {
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return parseInternal(v, defaultOptions())
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}
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// Parse parses a struct containing `env` tags and loads its values from
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// environment variables.
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func ParseWithOptions(v interface{}, opts Options) error {
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return parseInternal(v, customOptions(opts))
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}
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func parseInternal(v interface{}, opts Options) error {
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ptrRef := reflect.ValueOf(v)
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if ptrRef.Kind() != reflect.Ptr {
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return newAggregateError(NotStructPtrError{})
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}
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ref := ptrRef.Elem()
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if ref.Kind() != reflect.Struct {
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return newAggregateError(NotStructPtrError{})
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}
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return doParse(ref, opts)
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}
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func doParse(ref reflect.Value, opts Options) error {
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refType := ref.Type()
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var agrErr AggregateError
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for i := 0; i < refType.NumField(); i++ {
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refField := ref.Field(i)
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refTypeField := refType.Field(i)
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if err := doParseField(refField, refTypeField, opts); err != nil {
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if val, ok := err.(AggregateError); ok {
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agrErr.Errors = append(agrErr.Errors, val.Errors...)
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} else {
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agrErr.Errors = append(agrErr.Errors, err)
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}
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}
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}
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if len(agrErr.Errors) == 0 {
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return nil
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}
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return agrErr
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}
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func doParseField(refField reflect.Value, refTypeField reflect.StructField, opts Options) error {
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if !refField.CanSet() {
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return nil
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}
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if reflect.Ptr == refField.Kind() && !refField.IsNil() {
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return parseInternal(refField.Interface(), optionsWithEnvPrefix(refTypeField, opts))
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}
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if reflect.Struct == refField.Kind() && refField.CanAddr() && refField.Type().Name() == "" {
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return parseInternal(refField.Addr().Interface(), optionsWithEnvPrefix(refTypeField, opts))
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}
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value, err := get(refTypeField, opts)
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if err != nil {
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return err
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}
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if value != "" {
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return set(refField, refTypeField, value, opts.FuncMap)
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}
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if reflect.Struct == refField.Kind() {
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return doParse(refField, optionsWithEnvPrefix(refTypeField, opts))
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}
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return nil
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}
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const underscore rune = '_'
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func toEnvName(input string) string {
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var output []rune
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for i, c := range input {
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if i > 0 && output[i-1] != underscore && c != underscore && unicode.ToUpper(c) == c {
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output = append(output, underscore)
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}
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output = append(output, unicode.ToUpper(c))
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}
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return string(output)
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}
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func get(field reflect.StructField, opts Options) (val string, err error) {
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var exists bool
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var isDefault bool
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var loadFile bool
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var unset bool
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var notEmpty bool
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var expand bool
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required := opts.RequiredIfNoDef
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ownKey, tags := parseKeyForOption(field.Tag.Get(opts.TagName))
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if ownKey == "" && opts.UseFieldNameByDefault {
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ownKey = toEnvName(field.Name)
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}
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for _, tag := range tags {
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switch tag {
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case "":
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continue
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case "file":
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loadFile = true
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case "required":
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required = true
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case "unset":
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unset = true
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case "notEmpty":
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notEmpty = true
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case "expand":
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expand = true
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default:
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return "", newNoSupportedTagOptionError(tag)
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}
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}
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prefix := opts.Prefix
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key := prefix + ownKey
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defaultValue, defExists := field.Tag.Lookup("envDefault")
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val, exists, isDefault = getOr(key, defaultValue, defExists, opts.Environment)
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if expand {
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val = os.ExpandEnv(val)
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}
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if unset {
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defer os.Unsetenv(key)
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}
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if required && !exists && len(ownKey) > 0 {
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return "", newEnvVarIsNotSet(key)
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}
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if notEmpty && val == "" {
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return "", newEmptyEnvVarError(key)
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}
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if loadFile && val != "" {
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filename := val
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val, err = getFromFile(filename)
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if err != nil {
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return "", newLoadFileContentError(filename, key, err)
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}
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}
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if opts.OnSet != nil {
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if ownKey != "" {
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opts.OnSet(key, val, isDefault)
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}
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}
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return val, err
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}
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// split the env tag's key into the expected key and desired option, if any.
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func parseKeyForOption(key string) (string, []string) {
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opts := strings.Split(key, ",")
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return opts[0], opts[1:]
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}
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func getFromFile(filename string) (value string, err error) {
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b, err := os.ReadFile(filename)
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return string(b), err
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}
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func getOr(key, defaultValue string, defExists bool, envs map[string]string) (string, bool, bool) {
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value, exists := envs[key]
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switch {
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case (!exists || key == "") && defExists:
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return defaultValue, true, true
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case exists && value == "" && defExists:
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return defaultValue, true, true
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case !exists:
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return "", false, false
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}
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return value, true, false
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}
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func set(field reflect.Value, sf reflect.StructField, value string, funcMap map[reflect.Type]ParserFunc) error {
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if tm := asTextUnmarshaler(field); tm != nil {
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if err := tm.UnmarshalText([]byte(value)); err != nil {
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return newParseError(sf, err)
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}
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return nil
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}
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typee := sf.Type
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fieldee := field
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if typee.Kind() == reflect.Ptr {
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typee = typee.Elem()
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fieldee = field.Elem()
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}
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parserFunc, ok := funcMap[typee]
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if ok {
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val, err := parserFunc(value)
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if err != nil {
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return newParseError(sf, err)
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}
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fieldee.Set(reflect.ValueOf(val))
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return nil
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}
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parserFunc, ok = defaultBuiltInParsers[typee.Kind()]
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if ok {
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val, err := parserFunc(value)
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if err != nil {
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return newParseError(sf, err)
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}
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fieldee.Set(reflect.ValueOf(val).Convert(typee))
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return nil
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}
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switch field.Kind() {
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case reflect.Slice:
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return handleSlice(field, value, sf, funcMap)
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case reflect.Map:
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return handleMap(field, value, sf, funcMap)
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}
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return newNoParserError(sf)
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}
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func handleSlice(field reflect.Value, value string, sf reflect.StructField, funcMap map[reflect.Type]ParserFunc) error {
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separator := sf.Tag.Get("envSeparator")
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if separator == "" {
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separator = ","
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}
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parts := strings.Split(value, separator)
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typee := sf.Type.Elem()
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if typee.Kind() == reflect.Ptr {
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typee = typee.Elem()
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}
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if _, ok := reflect.New(typee).Interface().(encoding.TextUnmarshaler); ok {
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return parseTextUnmarshalers(field, parts, sf)
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}
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parserFunc, ok := funcMap[typee]
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if !ok {
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parserFunc, ok = defaultBuiltInParsers[typee.Kind()]
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if !ok {
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return newNoParserError(sf)
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}
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}
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result := reflect.MakeSlice(sf.Type, 0, len(parts))
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for _, part := range parts {
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r, err := parserFunc(part)
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if err != nil {
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return newParseError(sf, err)
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}
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v := reflect.ValueOf(r).Convert(typee)
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if sf.Type.Elem().Kind() == reflect.Ptr {
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v = reflect.New(typee)
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v.Elem().Set(reflect.ValueOf(r).Convert(typee))
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}
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result = reflect.Append(result, v)
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}
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field.Set(result)
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return nil
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}
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func handleMap(field reflect.Value, value string, sf reflect.StructField, funcMap map[reflect.Type]ParserFunc) error {
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keyType := sf.Type.Key()
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keyParserFunc, ok := funcMap[keyType]
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if !ok {
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keyParserFunc, ok = defaultBuiltInParsers[keyType.Kind()]
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if !ok {
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return newNoParserError(sf)
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}
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}
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elemType := sf.Type.Elem()
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elemParserFunc, ok := funcMap[elemType]
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if !ok {
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elemParserFunc, ok = defaultBuiltInParsers[elemType.Kind()]
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if !ok {
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return newNoParserError(sf)
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}
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}
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separator := sf.Tag.Get("envSeparator")
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if separator == "" {
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separator = ","
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}
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result := reflect.MakeMap(sf.Type)
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for _, part := range strings.Split(value, separator) {
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pairs := strings.Split(part, ":")
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if len(pairs) != 2 {
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return newParseError(sf, fmt.Errorf(`%q should be in "key:value" format`, part))
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}
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key, err := keyParserFunc(pairs[0])
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if err != nil {
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return newParseError(sf, err)
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}
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elem, err := elemParserFunc(pairs[1])
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if err != nil {
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return newParseError(sf, err)
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}
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result.SetMapIndex(reflect.ValueOf(key).Convert(keyType), reflect.ValueOf(elem).Convert(elemType))
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}
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field.Set(result)
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return nil
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}
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func asTextUnmarshaler(field reflect.Value) encoding.TextUnmarshaler {
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if reflect.Ptr == field.Kind() {
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if field.IsNil() {
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field.Set(reflect.New(field.Type().Elem()))
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}
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} else if field.CanAddr() {
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field = field.Addr()
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}
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tm, ok := field.Interface().(encoding.TextUnmarshaler)
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if !ok {
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return nil
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}
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return tm
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}
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func parseTextUnmarshalers(field reflect.Value, data []string, sf reflect.StructField) error {
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s := len(data)
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elemType := field.Type().Elem()
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slice := reflect.MakeSlice(reflect.SliceOf(elemType), s, s)
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for i, v := range data {
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sv := slice.Index(i)
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kind := sv.Kind()
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if kind == reflect.Ptr {
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sv = reflect.New(elemType.Elem())
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} else {
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sv = sv.Addr()
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}
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tm := sv.Interface().(encoding.TextUnmarshaler)
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if err := tm.UnmarshalText([]byte(v)); err != nil {
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return newParseError(sf, err)
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}
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if kind == reflect.Ptr {
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slice.Index(i).Set(sv)
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}
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}
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field.Set(slice)
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return nil
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}
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