AndroidX uses busytown/ directory to wrap build bot invocations to a single command per build target. Each one of these scripts receives DIST_DIR, OUT_DIR, and CHANGE_INFO enviroment variables. DIST_DIR is a directory for putting build artifacts that should be saved. OUT_DIR is a directory to write temporary build outputs. CHANGE_INFO points to a file that allows build system to know what changed for a given change that is being built.
AndroidX build bots use the Gradle Remote Build Cache to speed up build targets. We configure the GCP build cache Gradle plugin to connect to the GCP Storage bucket androidx-gradle-remote-cache in the androidx-ge project.