Bazel vs Open Build Service

Bazel is a free, open-source tool for automating software builds and tests across languages and platforms. Projects define targets in BUILD files using Starlark, which can also be used to create custom rules and macros. Bazel caches prior work and rebuilds what needs to change, while running tasks in parallel. It supports languages including C++, Java, Kotlin, Python, Go, and Rust, with outputs for desktop, server, Android, and iOS. Bazel runs on Linux, macOS, and Windows, and the documentation describes builds with 100,000 or more source files across multiple repositories. Sandboxing can make builds and tests more hermetic, and failures return a non-zero exit code for basic CI integration. Teams can share outputs through a remote cache, but must select and maintain its backend and secure access because it can contain binaries. IDE options include plugins for IntelliJ, Android Studio, CLion, and Visual Studio Code, plus Xcode integration. Bazel is not well suited to uncached deployment steps that change cloud configuration.

Open Build Service (OBS) builds and distributes binary packages from source code in a consistent, reproducible way. Each package is built in a fresh jailed environment; when a build succeeds, OBS rebuilds packages that depend on it. The service can release packages, updates, add-ons, appliances, and complete distributions for different operating systems and hardware architectures. Documented package formats include RPM, DEB, and Arch, with recipes in formats such as spec, dsc, KIWI, and mkosi. Teams can use access controls, branches, merge requests, and submission reviews to coordinate work. GitHub.com and GitLab.com integrations are supported, as are self-hosted GitHub, GitLab, and Gitea instances when network connectivity works. The API gives clients and external services access to OBS resources, while the osc command-line client can edit sources and metadata, start builds, and gather results. OBS is GPL-licensed free software, available on a reference server for open-source developers or for installation on users’ own hardware or in a data center. The listed plan is free.