Add APK signature

.gitignore

@@ -36,6 +36,7 @@ build/
 **/android/gradlew.bat
 **/android/local.properties
 **/android/**/GeneratedPluginRegistrant.java
+**/android/key.properties
 
 # iOS/XCode related
 **/ios/**/*.mode1v3

android/app/build.gradle

@@ -25,6 +25,10 @@ apply plugin: 'com.android.application'
 apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
+def keystorePropertiesFile = rootProject.file("key.properties")
+def keystoreProperties = new Properties()
+keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
+
 android {
     compileSdkVersion 27
 
@@ -45,11 +49,19 @@ android {
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
     }
 
+    signingConfigs {
+      release {
+        keyAlias keystoreProperties['keyAlias']
+        keyPassword keystoreProperties['keyPassword']
+        storeFile file(keystoreProperties['storeFile'])
+        storePassword keystoreProperties['storePassword']
+      }
+    }
+
     buildTypes {
-        release {
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig signingConfigs.debug
-        }
+      release {
+        signingConfig signingConfigs.release
+      }
     }
 }