AWS CodeBuild vs Buck2

AWS CodeBuild is a paid, cloud-hosted continuous integration service for compiling, testing, and packaging code from build scripts. It provisions and scales build capacity automatically, so projects do not require users to manage build servers. Preconfigured environments cover Java, Python, Node.js, Ruby, Go, Android, .NET Core for Linux, and Docker; teams can also supply Docker-based environments. A YAML build specification defines commands for each build phase and other settings. Builds can start from CodeCommit, GitHub, GitHub Enterprise, Bitbucket, Amazon S3, or CodePipeline, and can work with Jenkins. Artifacts can be stored in S3 or sent to an artifact repository. IAM provides access controls, while KMS keys encrypt artifacts. Build timing, status, commit ID, metrics, and logs are available through the service and CloudWatch, with SNS event notifications. A free plan provides stated monthly allowances; paid usage starts at 0.01 USD and can add charges for data transfer and related AWS services.

Buck2 is a free build system from Meta for large-scale repositories that combine multiple programming languages. It uses Starlark rules, a dynamic dependency graph, and incremental actions to support extensible builds. Its language table lists prelude rules for C/C++, Erlang, Go, Haskell, Java, Kotlin, OCaml, Python, and Rust, though usability varies by language. Build actions can run remotely through services exposing Bazel's remote execution API; the project lists BuildBarn, BuildBuddy, EngFlow, and NativeLink as compatible with its distributed compilation support. Buck2 supports filesystem watching and can integrate with Meta's optional Eden virtual filesystem. Rules are hermetic by default and missing dependencies are errors, but local-only build steps are not sandboxed. The project describes Buck2 as early-stage and says it has no stable release tag; its latest binary tag changes with repository pushes. It warns that outside users may encounter rough edges, missing features, and missing toolchains. Source and binaries are available under MIT and Apache-2.0 licenses. The project directs users to GitHub for issue reports and offers a community Discord server.