build: use env variables for release signing fallback

Author: naveensingh

app/build.gradle.kts

@@ -37,6 +37,13 @@ android {
                 storeFile = file(keystoreProperties.getProperty("storeFile"))
                 storePassword = keystoreProperties.getProperty("storePassword")
             }
+        } else {
+            register("release") {
+                keyAlias = System.getenv("SIGNING_KEY_ALIAS")
+                keyPassword = System.getenv("SIGNING_KEY_PASSWORD")
+                storeFile = file(System.getenv("SIGNING_STORE_FILE"))
+                storePassword = System.getenv("SIGNING_STORE_PASSWORD")
+            }
         }
     }
 
@@ -55,9 +62,7 @@ android {
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
             )
-            if (keystorePropertiesFile.exists()) {
-                signingConfig = signingConfigs.getByName("release")
-            }
+            signingConfig = signingConfigs.getByName("release")
         }
     }