Automating Play Store releases in Open Event Android with Fastlane

In Open Event Android we are using fastlane to automate the process of releasing the app to the Play Store, otherwise without this tool we would have to sign the release apk everytime before making a release but with fastlane all we need to do is just merge the development branch with the master branch and the updated app is released in Play Store.

The first thing that we need to do is encrypt the signing keys and upload it to the repository so we will create an encrypted tar file of the signing keys and upload it to the repository.

Now we want to decrypt the tar file everytime we merge our development branch into the master branch. We will create a bash script which does the above task which looks like this.

set -e


if [ "$TRAVIS_PULL_REQUEST" != "false" -o "$TRAVIS_REPO_SLUG" != "fossasia/open-event-android" -o "$TRAVIS_BRANCH" != "$DEPLOY_BRANCH" ]; then
 echo "We decrypt key only for pushes to the master branch and not PRs. So, skip."
exit 0

# Decrypt keys
openssl aes-256-cbc -K $encrypted_59a1db41ee4d_key -iv $encrypted_59a1db41ee4d_iv -in ./scripts/secrets.tar.enc -out ./scripts/secrets.tar -d
tar xvf ./scripts/secrets.tar -C scripts/


We need to define all these variables written after the $ sign as our Travis environment variables.

Next thing that we need to do is sign the apk so first thing that we check in the update-apk script is if we are on the master branch. We take the unsigned apk and sign it with the following commands.

 cp open-event-master-app-playStore-release-unsigned.apk open-event-master-app-playStore-release-unaligned.apk
jarsigner -verbose -tsa -sigalg SHA1withRSA -digestalg SHA1 -keystore ../scripts/key.jks -storepass $STORE_PASS -keypass $KEY_PASS open-event-master-app-playStore-release-unaligned.apk $ALIAS


The following command zipaligns the app

 ${ANDROID_HOME}/build-tools/27.0.3/zipalign -v -p 4 open-event-master-app-playStore-release-unaligned.apk open-event-master-app-playStore-release.apk


After signing the release apk, the final step is to publish the app to the playstore. The following command will install fastlane.

gem install fastlane


This command will take the signed apk and upload it in alpha channel of the playstore.

fastlane supply --apk open-event-master-app-playStore-release.apk --track alpha --json_key ../scripts/fastlane.json --package_name $PACKAGE_NAME


That’s it! Now releasing an update to the playstore is as simple as sending a pull request to the master branch. A process that would have otherwise required few minutes has been reduced to just seconds.


  1. Fastlane Official Site:
  2. Fastlane Android Documentaion:
  3. Fastlane Repository:
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Getting Signed Release apk’s from the command line


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If anyone of you has deployed an application on the play store, you may have most probably used Android Studio’s built in Generate signed apkoption.

The generate apk option in android studio

Recently while making the Open Event Apk generator, I had to make release apk’s, so that they could be used by an event organiser to publish their app, plus apk’s had to be signed because if they were not signed, it would be impossible to upload due to checks by Google.

Error shown on the developers console

So since I was building the app using the terminal and I didn’t have the luxury of signing the app using Android studio and I had to look for alternatives. Luckily I found two of them :

  1. Using the Signing configs offered by gradle
  2. Using the Oracle sun jarsigner

First of all the signing configs in gradle is a great way to do this. Most Open source apps use this as a way to put their code out for everyone to view and sucessfully hide any private keys and password.

You just need to add few lines of code in your app level build.gradle file and create a file called

In your, we just need to store the sensitive info and this file will be accessible only to people who are part of the project.


Next we go to the build.gradle and add these lines to read the file and it’s variables

// Create a variable called keystorePropertiesFile, and initialize it to your
// file, in the rootProject folder.
def keystorePropertiesFile = rootProject.file("")

// Initialize a new Properties() object called keystoreProperties.
def keystoreProperties = new Properties()

// Load your file into the keystoreProperties object.
keystoreProperties.load(new FileInputStream(keystorePropertiesFile))

Next we can add the signingConfigs task and reference the values we got above over there

android {
    signingConfigs {
        config {
            keyAlias keystoreProperties['keyAlias']
            keyPassword keystoreProperties['keyPassword']
            storeFile file(keystoreProperties['storeFile'])
            storePassword keystoreProperties['storePassword']

So As you see this is as simple as this but according to my requirements this seemed a bit tedious since a person setting up the apk generator had to make a keystore file, then find the build.gradle and change the path of the keystore file according to the server directories. So this does the trick but this can be so tedious for someone with no technical experience, so I researched on other solutions and then I got it : Jarsigner and Zipalign

First of all,the jarsigner and zipalign are 2 great tools and the best part about them is that both of them work perfectly with a just one line commands. For signing the app :

jarsigner -keystore <keystore_file> -storepass <storepassword> <apknameTosigned> <alias>

and then zipaligning :

zipalign -v 4 <unaligned-apk-location> <path-to-generated-aligned-apk>

So this is it, we finally used these 2 commands to sign and zipalign an apk and it works perfectly fine. Please test and share comments of the demo live @ Ciao !

Continue ReadingGetting Signed Release apk’s from the command line