mountassemble

Mountassemble is a conceptual software tool and workflow designed to unify the processes of mounting external filesystems and assembling deployment artifacts into a cohesive runtime image. It aims to simplify build and deployment pipelines by coordinating mounting, extraction, and composition steps into a single declarative process.

Its main features include manifest-driven configuration, support for multiple backends such as block devices, network shares, and archive formats, and the ability to assemble a final root filesystem or container image by layering sources with defined order and transformations. It emphasizes reproducibility by tracking sources, mount options, and assembly steps, and can perform cleanup and rollback.

An implementation typically consists of a CLI or daemon, a manifest schema, and a plugin system that provides backends for filesystems, archives, and image formats. The assembly engine applies rules to mount sources, apply transformations (such as extraction or file permission adjustments), and write the resulting image to a target directory or image file. Isolation is often provided via user namespaces and namespace-aware mounting.

Usage generally begins with creating a manifest that lists sources, mount points, and assembly steps. Running the tool mounts the specified resources and executes the assembly steps to produce a finalized artifact, such as a chroot-ready tree, a root filesystem tarball, or a container image. A separate cleanup phase unmounts resources and removes temporary state.

Applications include embedded system building, reproducible container image creation, live ISO or USB image assembly, and testing environments that require deterministic filesystem composition.

Origins are traced to discussions about reproducible builds and composable deployment in the early 2020s, with several experimental projects attempting to realize its core ideas. As a concept, mountassemble remains unofficial and is implemented in various forms by different groups.

See also: mounting, image building, overlay filesystem, union filesystem, container image creation.