signing config & build apk

android/app/build.gradle

@@ -25,6 +25,12 @@ apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
+def keystoreProperties = new Properties()
+def keystorePropertiesFile = rootProject.file('key.properties')
+if (keystorePropertiesFile.exists()) {
+    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+}
+
 android {
     compileSdkVersion flutter.compileSdkVersion
     ndkVersion flutter.ndkVersion
@@ -53,11 +59,22 @@ android {
         versionName flutterVersionName
     }
 
+    signingConfigs {
+       release {
+           keyAlias keystoreProperties['keyAlias']
+           keyPassword keystoreProperties['keyPassword']
+           storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
+           storePassword keystoreProperties['storePassword']
+       }
+   }
+
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig signingConfigs.debug
+            if (project.hasProperty("signRelease")) {
+                signingConfig signingConfigs.release
+            } else {
+                signingConfig signingConfigs.debug
+            }
         }
     }
 }