Bringing modern storage to Viber’s users

This blogpost is a collaboration between Google and Viber. Authored by Kseniia Shumelchyk from Google and Anton Novikov, Sergey Kozlov from Viber.

As a messaging app, Viber needs to store, process and share a significant amount of data. Viber aims to give its users an easy, fast, reliable and secure communication platform by providing an intuitive interface and operating with files in a privacy-preserving way. We believe the modern scoped storage paradigm provides this foundation for app developers and users.

Scoped storage was introduced in Android 10 with further improvements in Android 11 to provide better protection to app and user data on a platform level. Due to Viber's complexity, the team opted to incrementally implement the changes that were required to comply with scoped storage.

In this article, we’ll share how Viber handled the migration to scoped storage, focusing on what they did to optimize working with media files and other data in the app.

Managing storage across Android versions

Android’s storage model has evolved to adapt to changing privacy considerations, leading to the changes in the storage system APIs. Let’s take a look at key platform changes that affected the legacy Viber implementation.

Media directories

Scoped storage changes the way that apps store and access files on a device's external storage. Viber needed to evaluate the differences between the existing app's storage model and updated platform guidelines, followed by gradual application changes to work with files in scoped storage. Therefore Viber invoked the requestLegacyExternalStorage flag to temporarily opt-out of scoped storage on Android 10 until the app was fully compatible.

In order to adjust their app experience to scoped storage, Viber now contributes public media files to well-defined media collections using the MediaStore API. This way, the files are accessible in a device gallery, and can be read by other apps with the storage permission. Private media files are stored in the app-specific directory on external storage and are accessed via the internal ContentProvider .

Storage permissions

The other notable update is related to changes in the storage permissions model : Apps in scoped storage have unrestricted access to their app-specific directories on external storage and can contribute to well-defined media collections without requesting a runtime permission. This change will help Viber provide more granular control to their users:

“This addition supports our efforts to provide our users with the best security and privacy solutions we can provide supported by the Android OS, users will benefit from this added security later without needing to opt-in. We also added a new ‘Save to gallery’ option allowing users to choose to make their photos readable by other apps or not. Because chats may contain private images or videos,...