Android devices allows you to freely run your own apps on them. It is very easy to build a version of your game and copy it onto an Android device. This manual explains the steps involved in bundling your game for Android. During development, running your game through the development app is often preferred since it allows you to hot reload content and code wirelessly directly to your device.
Android requires that apps that you want to install are digitally signed. Unlike iOS where all certificates are issued by Apple, Android allows self signed apps so you can freely create certificates and keys required to sign apps.
The process of creating certificates and keys may seem complicated but as long as you are in development, Defold fully automates the process. When you create an Android application bundle from the editor you can provide a specific certificate and key. If you don’t, Defold generates a random certificate and a key and signs the resulting .apk (Android Application Package) file.
It is important to note that when it is time to release an app on Google Play, you will need to create a certificate and key that you use to sign the app. The reason is that when you intend to publish an updated version of the app, the updated .apk file needs to be signed with the same signature as the current version. If you sign with a different private key, Google Play will reject the .apk update and you will need to publish the game as a totally new app.
You can find more information from the Google Play developer console.
You need the to create certificates in .pem-format and keys in .pk8-format. You can generate these with the
$ openssl genrsa -out key.pem 2048 $ openssl req -new -key key.pem -out request.pem $ openssl x509 -req -days 9999 -in request.pem -signkey key.pem -out certificate.pem $ openssl pkcs8 -topk8 -outform DER -in key.pem -inform PEM -out key.pk8 -nocrypt
This will leave you with the files certificate.pem and key.pk8 that you can use to sign your application bundles.
Make sure that you store your certificate and key safely. If you lose them you will not be able to upload updated .apk file versions to Google Play.
The editor lets you easily create a stand alone application bundle for your game. Before bundling you can specify what icon(s) to use for the app, set version code etc in the “game.project” project settings file. To bundle select Project ▸ Bundle… ▸ Android Application… from the menu.
If you want the editor to automatically create random debug certificates, leave the Certificate and Private key fields empty:
If you want to sign your bundle with a particular certificate and key, specify the .pem and .pk8 files:
Press Create Bundle and you will then be prompted to specify where on your computer the bundle will be created.
The editor writes an .apk file which is an Android application bundle. This file can be copied to your device with the
adb tool (see below), or to Google Play via the Google Play developer console.
$ adb install Defold\ examples.apk 4826 KB/s (18774344 bytes in 3.798s) pkg: /data/local/tmp/my_app.apk Success
The Defold engine requires a number of different permissions for all engine features to work. The permissions are defined in the
AndroidManifest.xml, specified in the “game.project” project settings file. You can read more about Android permissions in the official docs. The following permissions are requested in the default manifest:
Google Play Billing is a service that lets you sell digital content from inside an Android app, or in-app. This permission is needed for in-app purchases to work.
Allows an application to write to external storage. Starting in API level 19, this permission is not required to read/write files in your application-specific directories returned by Context.getExternalFilesDir(String) and Context.getExternalCacheDir(). This permission is needed if you intend to save/load files from disk (using io.* or sys.save/load) outside of the folder provided by sys.get_save_file() and have
android:minSdkVersion set to less than 19 in the Android manifest. (Android official docs).
Allows using PowerManager WakeLocks to keep processor from sleeping or screen from dimming. This permission is needed to temporarily prevent the device from sleeping while receiving a push notification. (Android official docs)
adb command line tool is an easy to use and versatile program that is used to interact with Android devices. You can download and install
adb as part of the Android SDK Platform-Tools, for Mac, Linux or Windows.
Download the Android SDK Platform-Tools from: https://developer.android.com/studio/releases/platform-tools. You find the adb tool in /platform-tools/. Alternatively, platform specific packages can be installed through respective package managers.
On Ubuntu Linux:
$ sudo apt-get install android-tools-adb
On Fedora 18/19:
$ sudo yum install android-tools
On Mac OS X (Homebrew)
$ brew cask install android-platform-tools
You can veryfy that
adb works by connecting your Android device to your computer via USB and issue the following command:
$ adb devices List of devices attached 31002535c90ef000 device
If your device does not show up, verify that you have enabled USB debugging on the Android device. Open the device Settings and look for Developer options (or Development).
A bundle built with the debug mode version of the engine (i.e. “Debug” selected as variant during bundling) will send all its console output to the Android system log. Access the log with the
adb tool and give the
logcat command. You probably want to filter the output by a tag (
$ adb logcat -s "defold" --------- beginning of /dev/log/system --------- beginning of /dev/log/main I/defold ( 6210): INFO:DLIB: SSDP started (ssdp://192.168.0.97:58089, http://0.0.0.0:38637) I/defold ( 6210): INFO:ENGINE: Defold Engine 1.2.50 (8d1b912) I/defold ( 6210): INFO:ENGINE: Loading data from: I/defold ( 6210): INFO:ENGINE: Initialised sound device 'default' I/defold ( 6210): D/defold ( 6210): DEBUG:SCRIPT: Hello there, log! ...
Android detects that you try to install the app with a new certificate. When bundling debug builds, each build will be signed with a temporary certificate. Uninstall the old app before installing the new version:
$ adb uninstall com.defold.examples Success $ adb install Defold\ examples.apk 4826 KB/s (18774344 bytes in 3.798s) pkg: /data/local/tmp/Defold examples.apk Success