72 lines
2.9 KiB
HTML
72 lines
2.9 KiB
HTML
<article>
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<h1>Background</h1>
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<p>Fedora today is an extremely flexible system. One can find
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Fedora builds running on everything from hobbyist ARM devices,
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to workstations, to testing servers.
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</p>
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<p>
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This flexibility derives in large part from the fact that from a
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technological point of view, Fedora is a collection of packages.
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While pre-assembled "deliverables" such as the Live CDs are
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distributed by the project, they are only a temporary state.
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</p>
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<p>
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For example, as soon as they are installed, upgrading involves
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having a package manager that dynamically reassembles the system
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from newer parts in the Fedora package collection. One cannot
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file a bug against the "default offering" as a whole - a package
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must be chosen.
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</p>
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<p>
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Nearly every aspect of the Fedora infrastructure (and
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documentation) is structured in terms of packages, from
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user-facing tools such as Bugzilla and Bodhi, to developer tools
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such as Koji. The announced security updates are based on package
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names.
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</p>
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<p>
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In contrast for example, ChromeOS is delivered and updated as an
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pre-assembled atomic unit, targeted at specific hardware.
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ChromeOS is (compared to Fedora) completely inflexible, but
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fulfills a targeted role clearly well.
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</p>
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<h3>How OSTree allows a middle ground</h3>
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<p>
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Fundamentally, packages are partial filesystem trees with metadata
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- they are traditionally assembled by a package manager on every
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client machine into a complete bootable tree. It's important to
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emphasize that it is only these <emphasis>complete</emphasis>
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trees that users run.
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</p>
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<p>
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OSTree allows an OS distributor to
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ship <emphasis>multiple</emphasis> pre-built complete bootable
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filesystem trees, and furthermore, client machines can atomically
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switch between them, or even track multiple trees independently.
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</p>
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<p>
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This allows a middle ground between the two extremes of a
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combinatorial explosion of packages, and a singular OS.
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</p>
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<h3>Initial goals</h3>
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<p>
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The first goal of this project is to be an <i>additional</i>
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deployment option built in the Fedora infrastructure; possibly
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only for Fedora rawhide. Developers and testers can use OSTree to
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atomically replicate, upgrade to newer versions of, and transition
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between the pre-assembled trees produced by this build server.
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</p>
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<p>
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Notably in this phase, no common mechanism for additional software
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installation is provided. That said, individual trees can do so;
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for example <tt>server/docker-io</tt> tree can use Docker to
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install and run server container applications independent of
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OSTree.
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</p>
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<p>
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This phase does include basic integration testing on the build
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server side, which will be a major benefit to the Fedora project
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and its downstreams.
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</p>
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</article>
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