Merge bcab3ff5ff into 8ac644165c

util.go

@@ -17,6 +17,7 @@ import (
 	"runtime"
 	"strings"
 	"unicode"
+	"regexp"
 
 	slog "github.com/sagikazarmark/slog-shim"
 	"github.com/spf13/cast"
@@ -221,3 +222,17 @@ func deepSearch(m map[string]any, path []string) map[string]any {
 	}
 	return m
 }
+// We look up a environmental variable if it looks like '${HOME}'
+func lookupEnvByValue(s string) string {
+	match, err := regexp.MatchString("(\\$[A-Za-z_-]+|\\${[A-Za-z_-]+})", s)
+	if (err != nil) {
+		fmt.Println(match, err)
+	}
+	if (match) {	
+		env := os.ExpandEnv(s)
+		if ( env != "" ) {
+			return  env
+		}
+	}
+	return s
+}

viper.go

@@ -978,6 +978,12 @@ func (v *Viper) GetString(key string) string {
 	return cast.ToString(v.Get(key))
 }
 
+// GetStringEnv returns the value of the environmental variable associated with the key as a string.
+func GetStringEnv(key string) string { return lookupEnvByValue(v.GetString(key)) }
+func (v *Viper) GetStringEnv(key string) string {
+	return lookupEnvByValue(cast.ToString(v.Get(key)))
+}
+
 // GetBool returns the value associated with the key as a boolean.
 func GetBool(key string) bool { return v.GetBool(key) }
 

viper_test.go

@@ -48,6 +48,12 @@ import (
 // beard: true
 // `)
 
+var yamlExampleWithEnv = []byte(`
+home: '${HOME_STUFF}'
+undefined: '${UNDEFINED}'
+theclown: ${HOME_STUFF}
+`)
+
 var yamlExampleWithExtras = []byte(`Existing: true
 Bogus: true
 `)
@@ -708,6 +714,23 @@ func TestSetEnvKeyReplacer(t *testing.T) {
 	assert.Equal(t, "30s", Get("refresh-interval"))
 }
 
+func TestGetStringEnv(t *testing.T) {
+	Reset()
+	home := "."
+	os.Setenv("HOME_STUFF", home)
+	v := New()
+	v.SetConfigType("yaml")
+	v.ReadConfig(bytes.NewBuffer(yamlExampleWithEnv))
+	value := v.GetStringEnv("home")
+	// defined env variables are interpolated
+	assert.Equal(t, ".", value)
+	value = v.GetStringEnv("theclown")
+	assert.Equal(t, ".", value)
+	// undefined env variables are untouched
+	undefined_value := v.GetStringEnv("undefined")
+	assert.Equal(t, "${UNDEFINED}", undefined_value)
+}
+
 func TestEnvKeyReplacer(t *testing.T) {
 	v := NewWithOptions(EnvKeyReplacer(strings.NewReplacer("-", "_")))