Open Event Organizer is a client side android application of Open Event API server created for event organizers and entry managers. The application provides a way to configure the app name via environment variable app_name. This allows the user to change the app name just by setting the environment variable app_name to the new name. I will be talking about its implementation in the application in this blog.
Generally, in an android application, the app name is stored as a static string resource and set in the manifest file by referencing to it. In the Organizer application, the app name variable is defined in the app’s gradle file. It is assigned to the value of environment variable app_name and the default value is assigned if the variable is null. The relevant code in the manifest file is:
def app_name = System.getenv('app_name') ?: "eventyay organizer"
The default value of app_name is kept, eventyay organizer. This is the app name when the user doesn’t set environment variable app_name. To reference the variable from the gradle file into the manifest, manifestPlaceholders are defined in the gradle’s defaultConfig. It is a map of key value pairs. The relevant code is:
manifestPlaceholders = [appName: app_name]
This makes appName available for use in the app manifest. In the manifest file, app name is assigned to the appName set in the gradle.
By this, the application name is made configurable from the environment variable.
1. ManifestPlaceholders documentation
2. Stackoverflow answer about getting environment variable in gradle
The one click deploy button makes it easy for the users of loklak to get their own cloud instance created and deployed in their heroku account and can be used according to their flexibility. Heroku uses an app.json manifest in the code repo to figure out what add-ons, config and other deployment steps are required to make the code run. This is used to configure and deploy the app.
Once you have provide the app name and then click on deploy button, Heroku will start deploying the loklak server to a new app on your account:
When setup is complete, you can open the deployed app in your browser or inspect it in Dashboard.
All these steps and requirements can now be encoded in an app.json file and placed in a repo alongside a button that kicks off the setup with a single click.
App.json is a manifest format for describing apps and specifying what their config requirements are. Heroku uses this file to figure out how code in a particular repo should be deployed on the platform. Here is the loklak’s app.json file which used gradle build pack:
"name": "Loklak Server",
"description": "Distributed Tweet Search Server",
If you are interested you can try deploying the peer from here itself. Checkout how simple it can be to deploy.