This repository provides tools that can be used in combination with the Buildbarn storage daemon to add support for remote execution, allowing you to create a build farm that can be called into using tools such as Bazel, BuildStream and recc.
This repository provides three programs:
bb_scheduler: A service that receives requests frombb_storageto queue build actions that need to be run.bb_worker: A service that requests build actions frombb_schedulerand orchestrates their execution. This includes downloading the build action's input files and uploading its output files.bb_runner: A service that executes the command associated with the build action.
Most setups will run a single instance of bb_scheduler and a large
number of pairs of bb_worker/bb_runner processes. Older versions of
Buildbarn integrated the functionality of bb_worker and bb_runner
into a single process. These processes were decomposed to accomplish the
following:
- To make it possible to use privilege separation. Privilege separation
is used to prevent build actions from overwriting input files. This
allows
bb_workerto cache these files across build actions, exposing it to the build action through hardlinking. - To make execution pluggable.
bb_workercommunicates withbb_runnerusing a simple gRPC-based protocol. One could, for example, implement a custom runner process that executes build actions using QEMU user-mode emulation. - To work around a race condition
that effectively prevents multi-threaded processes from writing
executables to disk and spawning them. Through this decomposition,
bb_workerwrites executables to disk, whilebb_runnerspawns them.
This repository provides container images for each of these components.
For bb_runner, it provides two container images based on Google RBE's
Debian 8
and Ubuntu 16.04
images. The advantage of using these container images is that the Bazel
project provides ready-to-use toolchain definitions
for them.
Please refer to the Buildbarn Deployments repository for examples on how to set up these tools.