Refactor: Move SetViperStructDefaults to utils

Signed-off-by: Vyom-Yadav <[email protected]>
mindersec · Apr 3, 2024 · 2fa1d82 · 2fa1d82
1 parent 6f69727
commit 2fa1d82
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Showing 2 changed files with 88 additions and 87 deletions.
diff --git a/internal/config/server/config.go b/internal/config/server/config.go
@@ -18,12 +18,8 @@
 package server
 
 import (
-	"encoding/json"
 	"fmt"
-	"reflect"
-	"strconv"
 	"strings"
-	"unicode"
 
 	"github.com/spf13/viper"
 
@@ -66,87 +62,5 @@ func DefaultConfigForTest() *Config {
 func SetViperDefaults(v *viper.Viper) {
 	v.SetEnvPrefix("minder")
 	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_", "-", "_"))
-	setViperStructDefaults(v, "", Config{})
-}
-
-// setViperStructDefaults recursively sets the viper default values for the given struct.
-//
-// Per https://github.com/spf13/viper/issues/188#issuecomment-255519149, and
-// https://github.com/spf13/viper/issues/761, we need to call viper.SetDefault() for each
-// field in the struct to be able to use env var overrides.  This also lets us use the
-// struct as the source of default values, so yay?
-func setViperStructDefaults(v *viper.Viper, prefix string, s any) {
-	structType := reflect.TypeOf(s)
-
-	for i := 0; i < structType.NumField(); i++ {
-		field := structType.Field(i)
-		if unicode.IsLower([]rune(field.Name)[0]) {
-			// Skip private fields
-			continue
-		}
-		if field.Tag.Get("mapstructure") == "" {
-			// Error, need a tag
-			panic(fmt.Sprintf("Untagged config struct field %q", field.Name))
-		}
-		valueName := strings.ToLower(prefix + field.Tag.Get("mapstructure"))
-		fieldType := field.Type
-
-		// Extract a default value the `default` struct tag
-		// we don't support all value types yet, but we can add them as needed
-		value := field.Tag.Get("default")
-
-		// Dereference one level of pointers, if present
-		if fieldType.Kind() == reflect.Ptr {
-			fieldType = fieldType.Elem()
-		}
-
-		if fieldType.Kind() == reflect.Struct {
-			setViperStructDefaults(v, valueName+".", reflect.Zero(fieldType).Interface())
-			if _, ok := field.Tag.Lookup("default"); ok {
-				overrideViperStructDefaults(v, valueName, value)
-			}
-			continue
-		}
-
-		defaultValue := reflect.Zero(field.Type).Interface()
-		var err error // We handle errors at the end of the switch
-		//nolint:golint,exhaustive
-		switch fieldType.Kind() {
-		case reflect.String:
-			defaultValue = value
-		case reflect.Int64, reflect.Int32, reflect.Int16, reflect.Int8, reflect.Int,
-			reflect.Uint64, reflect.Uint32, reflect.Uint16, reflect.Uint8, reflect.Uint:
-			defaultValue, err = strconv.Atoi(value)
-		case reflect.Float64:
-			defaultValue, err = strconv.ParseFloat(value, 64)
-		case reflect.Bool:
-			defaultValue, err = strconv.ParseBool(value)
-		case reflect.Slice:
-			defaultValue = nil
-		default:
-			err = fmt.Errorf("unhandled type %s", fieldType)
-		}
-		if err != nil {
-			// This is effectively a compile-time error, so exit early
-			panic(fmt.Sprintf("Bad value for field %q (%s): %q", valueName, fieldType, err))
-		}
-
-		if err := v.BindEnv(strings.ToUpper(valueName)); err != nil {
-			panic(fmt.Sprintf("Failed to bind %q to env var: %v", valueName, err))
-		}
-		v.SetDefault(valueName, defaultValue)
-	}
-}
-
-func overrideViperStructDefaults(v *viper.Viper, prefix string, newDefaults string) {
-	overrides := map[string]any{}
-	if err := json.Unmarshal([]byte(newDefaults), &overrides); err != nil {
-		panic(fmt.Sprintf("Failed to parse overrides in %q: %v", prefix, err))
-	}
-
-	for key, value := range overrides {
-		// TODO: we don't do any fancy type checking here, so this could blow up later.
-		// I expect it will blow up at config-parse time, which should be earlier enough.
-		v.SetDefault(prefix+"."+key, value)
-	}
+	config.SetViperStructDefaults(v, "", Config{})
 }
diff --git a/internal/config/utils.go b/internal/config/utils.go
@@ -17,9 +17,14 @@
 package config
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
 	"path/filepath"
+	"reflect"
+	"strconv"
+	"strings"
+	"unicode"
 
 	"github.com/spf13/pflag"
 	"github.com/spf13/viper"
@@ -187,3 +192,85 @@ func ReadConfigFromViper[CFG any](v *viper.Viper) (*CFG, error) {
 	}
 	return &cfg, nil
 }
+
+// SetViperStructDefaults recursively sets the viper default values for the given struct.
+//
+// Per https://github.com/spf13/viper/issues/188#issuecomment-255519149, and
+// https://github.com/spf13/viper/issues/761, we need to call viper.SetDefault() for each
+// field in the struct to be able to use env var overrides.  This also lets us use the
+// struct as the source of default values, so yay?
+func SetViperStructDefaults(v *viper.Viper, prefix string, s any) {
+	structType := reflect.TypeOf(s)
+
+	for i := 0; i < structType.NumField(); i++ {
+		field := structType.Field(i)
+		if unicode.IsLower([]rune(field.Name)[0]) {
+			// Skip private fields
+			continue
+		}
+		if field.Tag.Get("mapstructure") == "" {
+			// Error, need a tag
+			panic(fmt.Sprintf("Untagged config struct field %q", field.Name))
+		}
+		valueName := strings.ToLower(prefix + field.Tag.Get("mapstructure"))
+		fieldType := field.Type
+
+		// Extract a default value the `default` struct tag
+		// we don't support all value types yet, but we can add them as needed
+		value := field.Tag.Get("default")
+
+		// Dereference one level of pointers, if present
+		if fieldType.Kind() == reflect.Ptr {
+			fieldType = fieldType.Elem()
+		}
+
+		if fieldType.Kind() == reflect.Struct {
+			SetViperStructDefaults(v, valueName+".", reflect.Zero(fieldType).Interface())
+			if _, ok := field.Tag.Lookup("default"); ok {
+				overrideViperStructDefaults(v, valueName, value)
+			}
+			continue
+		}
+
+		defaultValue := reflect.Zero(field.Type).Interface()
+		var err error // We handle errors at the end of the switch
+		//nolint:golint,exhaustive
+		switch fieldType.Kind() {
+		case reflect.String:
+			defaultValue = value
+		case reflect.Int64, reflect.Int32, reflect.Int16, reflect.Int8, reflect.Int,
+			reflect.Uint64, reflect.Uint32, reflect.Uint16, reflect.Uint8, reflect.Uint:
+			defaultValue, err = strconv.Atoi(value)
+		case reflect.Float64:
+			defaultValue, err = strconv.ParseFloat(value, 64)
+		case reflect.Bool:
+			defaultValue, err = strconv.ParseBool(value)
+		case reflect.Slice:
+			defaultValue = nil
+		default:
+			err = fmt.Errorf("unhandled type %s", fieldType)
+		}
+		if err != nil {
+			// This is effectively a compile-time error, so exit early
+			panic(fmt.Sprintf("Bad value for field %q (%s): %q", valueName, fieldType, err))
+		}
+
+		if err := v.BindEnv(strings.ToUpper(valueName)); err != nil {
+			panic(fmt.Sprintf("Failed to bind %q to env var: %v", valueName, err))
+		}
+		v.SetDefault(valueName, defaultValue)
+	}
+}
+
+func overrideViperStructDefaults(v *viper.Viper, prefix string, newDefaults string) {
+	overrides := map[string]any{}
+	if err := json.Unmarshal([]byte(newDefaults), &overrides); err != nil {
+		panic(fmt.Sprintf("Failed to parse overrides in %q: %v", prefix, err))
+	}
+
+	for key, value := range overrides {
+		// TODO: we don't do any fancy type checking here, so this could blow up later.
+		// I expect it will blow up at config-parse time, which should be earlier enough.
+		v.SetDefault(prefix+"."+key, value)
+	}
+}