Changes/Web Assets

Web Assets

Summary

Traditionally, Fedora has been pushing bits from its various servers to people's browsers in an ad-hoc fashion, and issues surrounding JavaScript have been swept under the rug. This change proposal provides a simple framework for shipping static web content and a way forward to treat JavaScript more closely to other code in the distribution.

Owner

• Name: T.C. Hollingsworth
• Email: tchollingsworth@gmail.com

Current status

• Targeted release: Fedora 21
• Last updated: 2014-01-18
• Tracker bug: F20WebAssets #998583

Detailed Description

A standard directory (/usr/share/web-assets) for static bits that are intended to be delivered to web browsers, such as CSS Frameworks, UI libraries, etc. will be introduced. HTTP daemons in the distribution should make this directory available publicly as /.sysassets.

Additionally, a standard directory (/usr/share/javascript) for JavaScript code, which may be used in browsers or server-side by applications such as nodejs or rubygem-execjs will also be introduced.

Finally, new packaging guidelines will provide instructions for making proper use of these new directories.

Benefit to Fedora

Packagers will benefit from clear guidelines for shipping JavaScript code and other modular content that can be used by multiple web applications.

By eliminating bundling of JavaScript code within web applications and replacing it with proper packaging, the security footprint of the distribution will be improved.

Scope

Fedora 20

This section describes tasks already completed during the Fedora 20 release cycle.

The web-assets RPM

Status: built

A web-assets package will be introduced. A preliminary SRPM is available here.

The web-assets-filesystem subpackage will be provided, which contains the following directories:

• /usr/share/web-assets
• /usr/share/javascript

Additionally the following symlinks will be provided:

• /usr/share/web-assets/javascript points to /usr/share/javascript
• /usr/share/web-assets/fonts points to /usr/share/fonts (so any Fedora font package can be used as a web font)

A web-assets-devel subpackage will be provided that provides macros like %{_assetdir} and other conveniences described in the proposed guidelines.

Fonts

Status: guidelines approved

Now that we're going to make many of the free fonts in the distribution available over the Internet, we'd like to take the opportunity to make sure the licensing metadata is populated in each of them so we can be sure we're complying with their licenses.

There are 80 fonts in 28 packages that are currently missing the necessary data. Additionally, the remainder will need to be audited to make sure they actually specify correct license data. (This will be mostly scripted away so it won't be too onerous.)

Finally, User:Patches/PackagingDrafts/FontsPolicy new guidelines will be put into effect to ensure this is done correctly in the future.

Flash

Status: bugs filed

It seems a number of packages contain precompiled Flash files. This has never been acceptable for Fedora. These packages will be identified and bugs will be filed as part of the cleanup tasks.

FPC

Status: guidelines approved

The Fedora Packaging Committee will need to consider and approve drafts pertaining to Web Assets and JavaScript.

FPC/FESCo

Status: effectively already done?

FPC/FESCo may or may not want to consider a firm date for sunsetting the bundled JavaScript exception and requiring all new packages to meet the new guidelines.

Fedora 21

This section describes tasks that are scheduled to be completed during the Fedora 21 release cycle.

The web-assets RPM

A web-assets-httpd package will make the web assets directory available at the final decided location.

httpd

httpd may want to add Requires: web-assets-httpd (or ship the configuration itself, though it was suggested that it would be better seperate) to make the assets directory available unconditionally by default. This will simplify packaging. (We really would prefer that JavaScript libraries not depend on httpd, as they could be used by Node.js or Ruby.)

FPC

FPC approved an initial guidelines draft during the Fedora 20 release cycle. Several issues were identified during the discussions of the F20 feature and guidelines both within Fedora and with other distributions (namely Debian) that will require amendments to the guidelines, namely:

• official guidelines for replacing directories with symlinks (fpc ticket #385)
• provide general recommendations for directory structure to avoid future pain, given Panu's comments in the above ticket
• switch http daemon path to /.sysassets to prevent it from appearing in directory listings if implemented as a symlink
• generalize the static inclusion guidelines to be useful for static linking and use plain Provides and not a macro

other HTTP daemons

It would be nice to support additional HTTP daemons as well. I'll investigate whether we can support them with drop-in configuration files or symlinks from other web-assets subpackages in addition to httpd.

Fonts

Now that we're going to make many of the free fonts in the distribution available over the Internet, we'd like to take the opportunity to make sure the licensing metadata is populated in each of them so we can be sure we're complying with their licenses. New guidelines were implemented during the Fedora 20 release cycle to prevent this from occurring in the future.

There are 80 fonts in 28 packages that are currently missing the necessary data. Additionally, the remainder will need to be audited to make sure they actually specify correct license data. (This will be mostly scripted away so it won't be too onerous.)

Flash

It seems a number of packages contain precompiled Flash files. This has never been acceptable for Fedora.

During the Fedora 20 release cycle, bugs were filed against packages that bundle these files. Many were fixed, some are still left to do. Work on this will continue during the Fedora 21 release cycle.

Foreign languages

Many foreign languages support JavaScript, like Ruby via rubygem-execjs or Java via rhino. Several of them already depend on existing JavaScript library packages (virtually all node.js-related ones) and will need to be modified to conform to the new locations specified by the guidelines.

Node.js

Several node packages ship JavaScript for the browser and will need to be modified to conform to the new guidelines.

Handwavy Future

JavaScript packagers

Some longstanding reviews (like jquery) can now be completed with clear guidelines, paving the way for web applications to start being migrating to using proper dependencies instead of bundling. Several will be targeted for the Fedora 21 release in separate Change requests.

All web applications currently in the distribution should be examined for bundled JavaScript, which should be packaged separately.

Web application packagers

Web applications can migrate to new JavaScript/Web Asset packages as they become available.

There are a lot of potentially affected packages. There's no hope of fixing them all in one release cycle, and even the dependency chain for jQuery, a big ticket package, could take several months to get reviewed and imported. Therefore, this Change proposal just seeks FESCo/FPC approval for a start to unravelling this madness. This will be a long transition, and will probably make the systemd transition look like a day in the park.

Just to give you an idea of the magnitude: there are 1836 packages that ship .js files, discounting Node.js packages. (Though those certainly all don't necessarily include bundled JS.) There's a lot of low-hanging fruit: for instance, there are 963 packages that ship a file called jquery.js, a whole bunch of which is just included as output from documentation generators like Sphinx or rdoc. (Though keep in mind that isn't necessarily the only JS these packages bundle.) More low hanging fruit can be gleamed from this list of frequencies of filenames ending in .js.

Upgrade/compatibility impact

None at this time.

Web Applications migrating their dependencies to the new framework will need to take care to provide a sane upgrade path, but that should be relatively simple.

How To Test

• Make sure the directories exist.
• Install httpd and web-assets-httpd, then verify that you can navigate to http://localhost/.sysassets/ and http://localhost/.sysassets/javascript/.

User Experience

Web Developers who want to use these libraries and frameworks in their applications will have a single place to look going forward.

Dependencies

• Requires added to httpd
• nodejs packages affected:
  • uglify-js
  • uglify-js1
  • coffee-script
  • nodejs-less
• Ruby packages affected:
  • rubygem-coffee-script
  • rubygem-coffee-script-source
  • rubygem-uglifier

FAQ

Why is /usr/share/javascript outside of /usr/share/assets?

Using /usr/share/javascript allows for consistency with other distributions (like Debian) and reflects the fact that JavaScript code can be run on Fedora itself as well as being pushed to the browser.

Why not just ship Apache configuration files for this kind of stuff like we've been doing/has been suggested before?

That leaves other http daemons and servers that don't involve traditional HTTP daemons (like many Node.js applications) hung out to dry. By just using a single, standard directory, and making that accessible from all HTTP daemons, support for many HTTP daemons is provided, and the need for packagers to keep up with changing Apache configuration formats just to ship a few simple JS files is eliminated.

Contingency Plan

None needed, either the directories get added or they don't.

Documentation

The new Packaging Guidelines referenced above.

Release Notes

Fedora 21 introduces standard directories for web assets (such as web user interface libraries) in /usr/share/web-assets, and JavaScript code in /usr/share/javascript. In future releases, web applications will be migrated to using shared components, eliminating the need for security updates to the same code in multiple packages.