Building images with Compose

Build is an optional part of the Compose Specification; it defines how to (re)build an application from source portably. build can be a single string defining a context path or a detailed build definition. As a string, the whole path is the Docker context for a Docker build, looking for a canonical Dockerfile at the directory's root; as a detailed structure, build arguments and an alternate Dockerfile location can be specified. Paths can be absolute or relative; relative paths resolve from the Compose file's directory, while absolute paths prevent portability, so Compose displays a warning. When both build and image are set, Compose follows the pull_policy attribute; without pull_policy, it pulls the image first, then builds from source if not found. Scope: Docker Compose. Reviewed October 4, 2026.