Storing Secret Keys

The recommended method to store secret keys (ie. Google Map API key) is through a properties file. Here are the steps for creating the file:

1. Create a keys.properties file (never push this!) and add the secret keys.

googleMapApiKey="AIzaSyBDjzqiK5_DVoZ-6nCSZNFwEYM9dr1q7MI"
fabricApiKey="50d77fbd594f6229f8bb9a3669ce18dce7dac38e"

2. Inside build.gradle (Module: app), add:

def keyFile = file('../keys.properties')
def keyProperties = new Properties()
keyProperties.load(new FileInputStream(keyFile))

android {
    ...
    defaultConfig {
        ...
        resValue 'string', "googleMapKey", keyProperties["googleMapApiKey"]
        resValue 'string', "fabricKey", keyProperties['fabricApiKey']
    }

3. Inside AndroidManifest.xml, add <meta-data> tags for each secret key.

<meta-data
 android:name="com.google.android.geo.API_KEY"
 android:value="@string/googleMapKey" />

<meta-data
 android:name="io.fabric.ApiKey"
 android:value="@string/fabricKey" />

Remember never to push this file to Github!