Platform Team/Guide/Sweets Packaging

Writing recipe files

See also 0sugar.recipe specification.

Package names

Within recipe files, Zero packages might be identified by several methods:

• current package (instead of a direct slug value, to make the recipe file more robust, move the slug option to the [DEFAULT] section and use %(slug)s interpolation),

<current-slug>[/<sub-package>]

• other packages from Bazaar that are accessible in the current project,

<other-package-slug>[/<sub-package>]

• direct 0install link.

<0install-feed-url>

At the end, all links will be transfered to 0install feed urls. The final 0install url will be in format:

http://sweets.sugarlabs.org/<Bazaar-project>/<slug>

Versioning

The versioning scheme for Zero packages can be arbitrary, since the version recipe option supports 0install version format. But in some cases, e.g., libraries, stricter versioning could be useful. In that case, the age recipe option should be used.

The recipe option age is intended to support, mostly, API breakages of library packages. But not ABI, because tracking an ABI is not trivial within the Sugar ecosystem (due to the enormous potential code base of varying quality) and of little utility, since packages may at any time rebuild from sources and multiple library versions may be installed (thanks to 0install).

Using the age option is simple, on every API breakage for the library package, increment the age value. Final package version will be:

<age-option>.<version-option>

Glob patterns

A pattern could be of two types:

• doesn't contain / or ** substrings, will be applied only to file names
• contains / or ** substring, will be applied to the full file path (relative to the root), thus could affect several directory levels

Only these pattern symbols are allowed:

• * matches everything, except directory separator
• ? matches any single character, except directory separator
• ** matches everything, including directory separator

Sub packages

By default, package is the singular and will be composed using [Package] or/and [Activity] sections. But if the package contains several logical components, it might have sub packages. In that case, the recipe file should contain additional sections (per sub package) in the form:

 [Package/<sub-package>]

Formatting of sub sections is identical to the [Package] section. Sub packages could make sense, e.g., for packaging additional content, or to separate a library and its script language binding.

Other packages can mention sub packages by the format:

<package>/<sub-package>

Good practise is using the following names for sub packages:

• python for Python binding,
• standalone if package might be used not only as Sugar activity but also as regular application (also, Application preset could be used for such sub packages).

Bundles

In some cases, e.g., to save storage space or bandwidth, it is useful to split a packaged application into several tarballs when some tarballs will contain any-arch data that are common for all platforms and another tarball will contain binaries for a particular platform. Thus, if an application supports several platforms, and any-arch data is big (multiple media, text, etc. files), duplicate tarballs are avoided.

The key differences between bundles and sub packages:

• Sub packages are logically independent parts of the package; bundles make sense only to save storage space;
• Each sub package is identified by a unique 0install url; all bundle components are identified by the same url;
• Tarballs for different sub packages will be extracted to different directories; bundle component tarballs, within the same bundle, will be extracted to the same directory.

Use the bundle option to declare a (sub)package(s) as a bundle:

 [Package]
 bundle = <bundle-component-name> [; ...]

and declare sections that contain components:

 [<component-name>]
 ...

Bundle component sections can contain only files-related options such as include, exclude, arch, and langs.

The same component could be a part of different bundles. In that case, the different package implementations will contain the same bundle component tarball.

Pitfalls

Devel packages

It is common practice in binary-based GNU/Linux distributions to use satellite devel packages to collect various build-time files like C headers or pkg-config files. In the 0install environment, this doesn't work, because every package is stored in a separate directory hierarchy, e.g., *.so symlinks, from devel package, will point to nothing, since all *.so.* files from the library package live in a separate directory.

Keep all build-time files in the runtime package.