Add support env variables in config file #143

pkg/shell/env.go

@@ -0,0 +1,31 @@
+package shell
+
+import (
+	"os"
+	"regexp"
+	"strings"
+)
+
+func ReplaceEnvVars(text string) string {
+	re := regexp.MustCompile(`\${([^}{]+)}`)
+	return re.ReplaceAllStringFunc(text, func(match string) string {
+		key := match[2 : len(match)-1]
+
+		var def string
+		i := strings.IndexByte(key, ':')
+		if i > 0 {
+			key, def = key[:i], key[i+1:]
+		}
+
+		value, exists := os.LookupEnv(key)
+		if exists {
+			return value
+		}
+
+		if def != "" {
+			return def
+		}
+
+		return match
+	})
+}