Stop Wasting Time - Adopt Gradle Remote Build Cache
Posted on 2022-07-13

In Caches Everywhere post I called out Gradle Remote Build Cache (RBC) as one of the types of caches in Gradle. If you are on a project that has more than a handful of people, and you are not using RBC, then you are wasting precious engineering time. This post will explain how to get it working using a Google Cloud Storage bucket.

RBC allows you for a given set of inputs to only run this task once across all of your developers. After RBC is filled with the task result, the rest of the developers directly download the output from RBC instead of rerunning this task again. This means you get to skip heavy hitters like Kotlin compile, JVM tests, and Android Lint. This results in huge time savings!

The AndroidX team has created GCP Gradle Build Cache Plugin to make it easy to get going. explains how to apply the plugin in your settings.gradle(.kts) and how to set up a Google Cloud Storage bucket.

The flow that we found works best for AndroidX project is to only push to RBC from the post-submit CI, whereas pre-submit CI and local developers get read access to RBC. This makes sure that the cache does not have a lot of churn as PRs and local changes are being built.

The whole setup ends up being:

plugins {
  id("") version "XXX"
buildCache {
    registerBuildCacheService(GcpBuildCache, GcpBuildCacheServiceFactory)
    remote(GcpBuildCache) {
        projectId = "..."
        bucketName = "..."
        push = isPostSubmitCi

For a large project with hundreds of modules like AndroidX, we went from taking minutes to seconds for most tasks both locally and in CI. This lets our engineers stay in the flow and be more productive. It terms of cost, it is less than <$500 per month with hundreds of CI builds a day and a long list of contributors.

Here is an example of how tasks get a lot of cache hits:

Screenshot of build scan showing cache hits

You can also browse the AndroidX Gradle Enterprise page to see the remote cache hits for yourself instead of just taking my word for it.