Buildbarn
Buildbarn Remote Execution is an open-source toolkit for creating a build farm that runs build actions remotely.
What Buildbarn is
Buildbarn Remote Execution is an open-source toolkit for creating a build farm that runs build actions remotely. It provides a scheduler to queue actions, a worker to coordinate execution and file transfers, and a runner to execute commands. Bazel, BuildStream, and recc are named as clients that can call a Buildbarn build farm. The tools work with Buildbarn’s storage daemon, and deployments can range from a single-node remote caching setup to large-scale remote execution.
Buildbarn provides container images and example deployments, including Docker Compose and Kubernetes configurations. Separating worker and runner processes supports privilege separation intended to help prevent build actions from overwriting input files. The worker communicates with the runner through a gRPC-based protocol, which allows custom runner implementations, including one using QEMU user-mode emulation. The runner’s bare image contains no userland or Linux installation, so build actions may need a userland environment. The deployment guide also notes possible glibc version mismatches between build and remote environments. The remote execution repository lists an Apache-2.0 license.
Good
- Open-source under Apache-2.0.
- Provides scheduler, worker, and runner components.
- Supports container-based deployment examples.
- Can scale from single-node caching to large execution setups.
- Worker-runner separation supports privilege separation.
Watch out
- Remote execution depends on Buildbarn’s storage daemon.
- Bare runner image contains no userland or Linux installation.
- Remote builds may encounter glibc version mismatches.
Who it suits
Buildbarn may suit teams that need self-hosted remote build execution or caching and use tools such as Bazel, BuildStream, or recc. It also offers a route to custom runner implementations and container-based deployment.
Verdict
Buildbarn provides the core services and deployment examples for remote build execution, from caching to larger setups. Build actions may require a userland environment, and the deployment guide identifies glibc mismatches as a possible issue.
The facts
Each one read from Buildbarn's own pages, with the date it was checked.
What it does
- Build clients
- The project names Bazel, Buck2, BuildStream, and recc as tools that use the Remote Execution protocol.checked 5 Oct 2026
- Build services
- The repository provides bb_scheduler to queue build actions, bb_worker to coordinate their execution and file transfers, and bb_runner to execute commands.checked 4 Oct 2026
- Commercial hosting
- Listed commercial hosting options include self-hosted managed Buildbarn and cloud-hosted Buildbarn services.checked 5 Oct 2026
- Deployment
- The project provides container images for its components and links to example deployments.checked 4 Oct 2026
- Deployment caveat
- The Buildbarn deployment guide notes that remote builds can encounter glibc version mismatches between the build environment and the remote environment.checked 5 Oct 2026
- Deployment options
- The project provides container images for its components, and its deployment examples include Docker Compose and Kubernetes configurations.checked 5 Oct 2026
- Deployment scale
- Buildbarn deployments can range from single-node remote caching setups to large-scale remote execution setups.checked 4 Oct 2026
- Execution architecture
- The worker communicates with the runner over a gRPC-based protocol, allowing a custom runner such as one using QEMU user-mode emulation.checked 5 Oct 2026
- Extensibility
- bb_worker communicates with bb_runner over a gRPC-based protocol, allowing custom runner implementations such as one using QEMU user-mode emulation.checked 4 Oct 2026
- License
- The remote execution repository is published under the Apache-2.0 license.checked 5 Oct 2026
- Monitoring
- The storage daemon configuration supports Prometheus metrics and pprof diagnostics.checked 5 Oct 2026
- Operational requirement
- The bb_runner_bare image contains no userland or Linux installation, and build actions may require a userland environment.checked 4 Oct 2026
- Privilege separation
- Separating worker and runner processes supports privilege separation to help prevent build actions from overwriting cached input files.checked 5 Oct 2026
- Purpose
- Buildbarn implements the Remote Execution protocol to cache and optionally execute build actions remotely.checked 5 Oct 2026
- Remote execution tools
- The remote execution repository provides a scheduler, worker, and runner for queuing and executing build actions.checked 5 Oct 2026
- Scale
- Buildbarn deployment examples describe use cases ranging from single-node remote caching to large-scale remote execution.checked 5 Oct 2026
- Security configuration
- The storage daemon supports configurable authorizers for cache and execution operations; its README example uses allow-all authorizers.checked 5 Oct 2026
- Security design
- Separating bb_worker and bb_runner enables privilege separation intended to prevent build actions from overwriting input files.checked 4 Oct 2026
- Storage dependency
- Remote execution tools work in combination with Buildbarn’s storage daemon.checked 5 Oct 2026
- Support
- Buildbarn points users to a community Slack channel and lists community members and companies offering commercial support or hosting.checked 5 Oct 2026
