support json schema

pkg/app/schema.go

@@ -0,0 +1,40 @@
+package app
+
+import (
+	"encoding/json"
+
+	js "github.com/swaggest/jsonschema-go"
+)
+
+// Generates json schema for app's config.AppConfig
+func (app *App) Schema() ([]byte, error) {
+	r := js.Reflector{}
+
+	s, err := r.Reflect(*app.cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	return json.MarshalIndent(s, "", "  ")
+}
+
+// Generates json schema for custom config
+// which embeds *config.AppConfig into it
+// Panics if no *config.AppConfig is embedded into custom
+// config type
+//
+// See swaggest/jsonschema-go for struct tag docs
+func CustomSchema[T any](target T) ([]byte, error) {
+	if err := HasAppConfig(target); err != nil {
+		panic(err.Error())
+	}
+
+	r := js.Reflector{}
+
+	s, err := r.Reflect(target)
+	if err != nil {
+		return nil, err
+	}
+
+	return json.MarshalIndent(s, "", "  ")
+}