Advanced Features

Client-server Mode

Fatbuildr uses a software architecture with multiple components following the client/server model. Also, fatbuildrweb component provides a secure REST API to offer fatbuildrd services over HTTP protocol and TCP/IP networks.

This enables the possibility to deploy distributed setup with fatbuildrd and fatbuildrweb components on a centralized server for a team of developpers running fatbuildrctl and web browser on workstations.

All developers can share centralized and mutualized resources to build and distribute software.


Build pipelines can be defined with optional derivatives that are complementary distributions. These additional distributions can be used for multiple purposes, such as distributing:

  • Multiple versions of an artifact for a target environment (ex: version X and version Y for el8),

  • Alternative versions of artifact (eg. with specific configuration flags) for particular hosts or hardware.

Multiple Sources support

Packages artifacts can be defined with multiple source archives, with one main artifact source and several supplementary sources. This is notably a convenient feature to do vendoring of build or runtime dependencies. Other sources or prebuilt artifacts (eg. minimized javascript libraries) can be directly integrated into the source tree and the binary packages. This saves the requirement to maintain many individual artifacts for software dependencies.

Fatbuildr follows strict principles to extract the source archives into a deterministic and predictable source tree, designed to help development of packaging code by making it consistent accross version and formats and reduce maintenance cost over time eventually.

Most archives formats such as zip files and all compressed tarball formats are natively supported.


Fatbuildr supports building artifacts for basically any hardware CPU architecture, including architectures non-natively compatible by the host system (ex: build for ARM architecture on x86_64 host). This feature is possible thanks to awesome qemu-user-static CPU emulation tool and Linux binfmt registration. This feature is available out-of-the-box in Fatbuildr without any additional setup required.

Automatic Static Analysis

After successful builds of RPM and Deb packages, Fatbuildr automatically runs reference static analysis tools and reports defects in artifacts to help users quickly spot common bugs and get relevant advices to produce high quality packages. It also reports packages content, with all files and permissions, to provide a quick glance on build results.

Automatic Changelogs

Fatbuildr can be given the responsability of generating Deb and RPM packages changelogs incrementally with successive builds. Developers do not need to manually define packages changelog entries with its share of errors and misinformation. Fatbuildr ensures packages changelog are always kept in sync with package builds with a full history of publications in repositories.

Incremental Versionning

When users submit artifact rebuild with the same version and release number, Fatbuildr detect it and automatically increment the artifact release version.

This notably protect from situations where packages repositories host successively slightly different binary artifacts with the same version number and filename, leading to potential proxy cache or package database corruptions.

The feature also enables users the possibilty to rebuild artifacts, typically in case of build dependencies update, without any further manual change in artifact definition.

Integrated Patchs Management

Fatbuildr provides integrated patchs queue management of upstream sources. It creates a temporary Git repository with software upstream sources, and users can add successive patches by directly creating commits on this Git repository. When user is done, commits are exported into a series of patches.

These patches are automatically integrated by Fatbuildr within the artifact and applied on sources at the beginning of the builds.

Users have an easy way to modify source codes of external software with their own fixes and changes, and maintain this serie of patches for future versions of this external software.

Interactive Builds

Users can submit interactive builds in Fatbuildr. In case of build failure, users drop into an interactive shell in the targeted build environment for debugging. Users can launch commands and even install additional tools to help for diagnosis. Interactive sessions can also be shared by multiple users for collaborative work.


Users can define shell prescripts for artifacts. These scripts can be used to dynamically perform any modification in the software source tree before the actual build of the artifact. These scripts are executed by Fatbuildr isolated in the build environment with external network access.

These scripts are typically used to do vendoring of external build dependencies not available in Linux distribution package repositories (eg. Go or javascript libraries).

The modifications realized by prescripts can either be exported to:

  • An additional patch integrated in the artifact patch queue

  • Or supplementary tarballs along the unmodified upstream tarball

Support of Unreleased Software

Fatbuildr can generate source tarball out of a source tree, tagged with user-provided version number, to build an artifact with this software. This feature can be used to distribute versions of software that is not yet released (eg. development version) or support software without publishing release model.

Web Interface & REST API

The optional Fatbuildrweb component provides both a secure REST API and web interface to Fatbuildr instances. This web interface can be used to explore content of artifact registries in graphical and intuitive manner.

Advanced Security Model

Fatbuildr implements by default many security hardening features under the hood, without additional complexity for end users and administrators:

  • Checksums of externally downloaded software are systematically verified.

  • Integrated GPG signing keyring are generated and protected with randomly generated passphrase.

  • D-Bus services API permissions are controled using Polkit and configurable policy.

  • Permissions to access REST API and web interface are managed with fine-grained RBAC policy and JWT tokens based authentication.

Resilient Service

The fatbuildrd daemon is a D-Bus activated service that starts automatically when needed and stop after some time of inactivity to free the resources. It includes a watchdog that detect internal failure and trigger automatic restart for quick service recovering.