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* add envparse package Signed-off-by: Sarah Funkhouser <[email protected]> * go mod tidy Signed-off-by: Sarah Funkhouser <[email protected]> --------- Signed-off-by: Sarah Funkhouser <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,2 @@ | ||
| // Package envparse provides a way to parse environment variables from a struct | ||
| package envparse |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| package envparse | ||
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| import ( | ||
| "errors" | ||
| "fmt" | ||
| "reflect" | ||
| "strings" | ||
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| "github.com/stoewer/go-strcase" | ||
| ) | ||
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| // ErrInvalidSpecification indicates that a specification is of the wrong type. | ||
| var ErrInvalidSpecification = errors.New("specification must be a struct pointer") | ||
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| type Config struct { | ||
| // FieldTagName is the name of the struct tag to use for the field name | ||
| FieldTagName string | ||
| // Skipper is the value of the tag to skip parsing of the field | ||
| Skipper string | ||
| } | ||
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| // varInfo maintains information about the configuration variable | ||
| type varInfo struct { | ||
| FieldName string | ||
| FullPath string | ||
| Key string | ||
| Type reflect.Type | ||
| Tags reflect.StructTag | ||
| } | ||
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| // GatherEnvInfo gathers information about the specified struct, including defaults and environment variable names. | ||
| func (c Config) GatherEnvInfo(prefix string, spec interface{}) ([]varInfo, error) { | ||
| s := reflect.ValueOf(spec) | ||
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| // Ensure the specification is a pointer to a struct | ||
| if s.Kind() != reflect.Ptr { | ||
| return nil, ErrInvalidSpecification | ||
| } | ||
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| s = s.Elem() | ||
| if s.Kind() != reflect.Struct { | ||
| return nil, ErrInvalidSpecification | ||
| } | ||
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| typeOfSpec := s.Type() | ||
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| // Create a slice to hold the information about the configuration variables | ||
| var infos []varInfo | ||
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| // Iterate over the struct fields | ||
| for i := range s.NumField() { | ||
| f := s.Field(i) | ||
| ftype := typeOfSpec.Field(i) | ||
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| if !f.CanSet() { | ||
| continue | ||
| } | ||
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| for f.Kind() == reflect.Ptr { | ||
| if f.IsNil() { | ||
| if f.Type().Elem().Kind() != reflect.Struct { | ||
| // nil pointer to a non-struct: leave it alone | ||
| break | ||
| } | ||
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| // nil pointer to struct: create a zero instance | ||
| f.Set(reflect.New(f.Type().Elem())) | ||
| } | ||
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| f = f.Elem() | ||
| } | ||
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| // Capture information about the config variable | ||
| fieldName := c.getFieldName(ftype) | ||
| if fieldName == c.Skipper { | ||
| continue | ||
| } | ||
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| info := varInfo{ | ||
| FieldName: fieldName, | ||
| FullPath: ftype.Name, | ||
| Type: ftype.Type, | ||
| Tags: ftype.Tag, | ||
| } | ||
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| // Default to the field name as the env var name (will be upcased) | ||
| info.Key = info.FieldName | ||
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| if prefix != "" { | ||
| info.Key = fmt.Sprintf("%s_%s", prefix, info.Key) | ||
| info.FullPath = fmt.Sprintf("%s.%s", strcase.LowerCamelCase(strings.Replace(prefix, "_", ".", -1)), info.FieldName) // nolint: gocritic | ||
| } | ||
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| info.Key = strings.ToUpper(info.Key) | ||
| infos = append(infos, info) | ||
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| if f.Kind() == reflect.Struct { | ||
| innerPrefix := prefix | ||
|
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| if !ftype.Anonymous { | ||
| innerPrefix = prefix + "_" + info.Tags.Get("json") | ||
| } | ||
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| embeddedPtr := f.Addr().Interface() | ||
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| // Recursively gather information about the embedded struct | ||
| embeddedInfos, err := c.GatherEnvInfo(innerPrefix, embeddedPtr) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
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| infos = append(infos[:len(infos)-1], embeddedInfos...) | ||
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| continue | ||
| } | ||
| } | ||
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| return infos, nil | ||
| } | ||
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| func (c Config) getFieldName(ftype reflect.StructField) string { | ||
| if ftype.Tag.Get(c.FieldTagName) != "" { | ||
| return ftype.Tag.Get(c.FieldTagName) | ||
| } | ||
|
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| // default to skip if the koanf tag is not present | ||
| return c.Skipper | ||
| } |
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