DEP 3 - Sources of software used by DebOps roles




Sources of software used by DebOps roles


Maciej Delmanowski, Robin Schneider




Standards Track






This document defines the sources and methods of software installation allowed in the Ansible roles included in the DebOps project.

Goals of the Policy

One of the goals of the DebOps Project is to provide a framework for a reliable, secure and reproducible management of servers and workstations "in production", which means hosts that are used in production environment, on live Internet-facing networks. For that to be possible, the project needs to have a clear set of rules about how and from where to get the software required to manage these hosts.

Host Operating System(s)

For the server machines, base Linux distribution selected to be used with the DebOps Project is the current Debian GNU/Linux Stable release.

Due to how Debian development occurs, some systems managed by DebOps might switch from Debian Stable to Debian Oldstable release during their life cycle. Therefore, DebOps SHOULD support current Debian Oldstable release at least as long, as its officially supported by Debian security updates. However, some time after next Debian Stable release, due to incompatibilities between releases various parts of the DebOps Project are expected to only support current Debian Stable.

Support for Debian LTS release is optional, depending on the status of the release and interested user base.

For other systems (workstations, laptops, etc.) preferred OS distributions are Debian GNU/Linux and Debian derivatives like Ubuntu Linux, or others, depending on the choice of the administrator. Support for these distributions may vary, any required changes to make the roles and playbooks work on other Debian-based systems are welcome.

Support for different Linux variants in different roles might be considered in the future, depending on compatibility or amount of the differences between these distributions and Debian and its derivatives.

Software repositories and sources

Software used on hosts managed using the DebOps Project comes from various sources. This is a list of these sources, ordered from the most to least preferred and supported by the project maintainers:

Debian Software Repository - Stable release

This repository is considered the most reliable source of software. Packages here are guaranteed to be stable (without any changes apart from security updates), signed and trusted by Debian Developers. The Debian Software Repository is considered to be reliable due to the requirement of software sources included in the Repository, as well as availability of multiple mirrors worldwide. The availability of binary packages ensures that no unnecessary dependencies are needed on production systems which increases reliability and security.

Debian Software Repository - Stable Backports

Packages backported from the next Debian release (Testing) are considered less stable than the current Debian Stable releases. However, due to build process based on Debian Stable packages and presence in the Debian Software Repository, they are considered as compatible with Debian Stable and considered less risky than packages from external repositories. It is preferred that software packages from outside of Debian SHOULD be made accessible via Debian Backports after getting through usual Debian package management process (Unstable, Testing).

Local APT repositories

APT packages built by the local system administrator or developer and distributed using a local APT repository are an acceptable alternative to the Debian Software Repository. This software source can be used to check if Debian Testing packages can be backported to Debian Stable before using it in production.

Upstream APT repositories

APT repositories provided by a software vendor with binary .deb packages that are signed by a valid OpenPGP key should be available if necessary in the Ansible roles or playbooks. However unless the software is not available in Debian Software Repository, upstream repositories MUST require a condition that enables them. This should give the local system administrators an option to install either Debian or upstream version of the package as they see fit.

Configuration required to enable these repositories (installation of an OpenPGP key and configuration of APT sources) should be performed using the debops.extrepo role. If the software vendor repository is missing in the extrepo default list, it should be added to it.

In certain cases, for example support for other Linux distributions, selection of alternative mirrors or variants of an APT repository, configuration of APT sources should be performed using Ansible primitives (apt_key, apt_repository Ansible modules) instead of the scripts provided by the software vendor. The debops.keyring role provides a convenient mechanism to configure these details.

Open Source software distributed as binary archives

Some software vendors release binary archives of Open Source software built from the published sources. This method of installation is acceptable only in a case where the software vendor provides a means of authentication of said binary archives, for example through hashes of the files authenticated by known OpenPGP keys that belong to the software vendor. The Ansible roles which use this method of installation MUST validate downloaded archives against the provided hashes, authenticity of which is checked using the OpenPGP keys.

Software installed from git repositories

Some software packages (for example, web-based applications) are distributed using git repositories. Programs installed in this fashion are acceptable, provided that the repository itself is downloaded first to ensure that the source code is available. If a repository contains a "stable" branch or its equivalent, it should be preferable to a latest stable tag which should be considered before "development" branch. If software distributed this way requires compilation, and vendor provides releases of binaries or tarballs through the git repository or an alternative method, they might be considered for use as well, when software is managed directly on production servers. If git repository contains instructions that make building a .deb package easier, this option should be considered as a preferable with instructions how to do it in the Ansible role documentation, in which case installation from git sources should be provided as an option. If the repository provides signed releases, they MUST be verified and used. It can be considered to require a certain commit hash corresponding to a signed release. A certain (ideally audited) commit hash MUST be specified in case no code signing is used to provide at least some sort of authenticity in conjunction with the DebOps Code Signing Policy.

Software installed by other package managers

Package managers other than APT, like pip, gem, phar, etc. are considered less reliable than software installed from source repositories. Different package managers might have different security practices, less stable software and reliability issues, and potentially might induce dependency issues in the managed systems, therefore software from Debian Software Repository should have priority if possible. If not possible, it should be tried to install most of the dependencies of the program from Debian Software Repository.