PackagingDrafts:Node.js

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=== BuildRequires ===
 
=== BuildRequires ===
  
To build a native module designed to be built with node-gyp, add <code>BuildRequires: node-gyp</code>, along with [#BuildRequires|''nodejs-devel''] and ''-devel'' packages for any shared libraries needed by the module.
+
To build a native module designed to be built with node-gyp, add <code>BuildRequires: node-gyp</code>, along with <code>BuildRequires: nodejs-devel</code> and ''-devel'' packages for any shared libraries needed by the module.
  
 
=== %build ===
 
=== %build ===

Revision as of 18:59, 22 January 2013

Warning (medium size).png
This is a draft.
These draft guidelines have not been approved by FPC and are incomplete (most notably missing anything about native (binary) modules).

Original Author: T.C. Hollingsworth
Based on the guidelines of other interpreted languages like Ruby and Python.

Contents

Naming Guidelines

  • The name of a Node.js extension/library package must start with nodejs- then the upstream name or name used in the npm registry. For example: nodejs-foomodule. While it is uncommon for a package's name to contain node, if it does, you should still add the nodejs prefix. For instance, the npm registry contains a uuid and a node-uuid module, which would need to be named nodejs-uuid and nodejs-node-uuid, repsectively.
  • Application packages that mainly provide tools (as opposed to libraries) that happen to be written for Node.js must follow the general naming guidelines instead.

BuildRequires

To build a package containing pure JavaScript node modules, you need to have:

BuildRequires: nodejs-devel

Additional BuildRequires may be necessary for native modules. See #Building native modules with node-gyp for more information.

Macros

In Fedora 18 and later, as well as EPEL 6, the following macros are defined for you:

Macro Normal Definition Notes
__nodejs %{_bindir}/node The Node.js interpreter
nodejs_version e.g. 0.9.5 The currently installed version of Node.js.
nodejs_sitelib %{_prefix}/lib/node_modules Where Node.js modules written purely in JavaScript are installed
nodejs_sitearch %{_prefix}/lib/node_modules Where native C++ Node.js modules are installed
nodejs_symlink_deps %{_bindir}/nodejs-symlink-deps See #Symlinking Dependencies below.
nodejs_fixdep %{_bindir}/nodejs-fixdep See #Correcting Dependencies
Note.png
Node does not support multilib.
Since npm and the node interpreter have no knowledge of multilib, %nodejs_sitelib and %nodejs_sitearch currently point to the same directory. The split is reserved in the event that the interpreter gains multiarch support or pure JavaScript modules move to /usr/share.
Questionmark.png
Needs FESCo Exemption
A FESCo multilib exemption is needed here. Since there is a similar exemption for java I think this would be granted.

These macros are provided by the nodejs package.

During %install or when listing %files you can use the %nodejs_sitelib or %nodejs_sitearch macro to specify where the installed modules are to be found. For instance:

%files
# A pure JavaScript node module
%{nodejs_sitelib}/foomodule/
# A native node module
%{nodejs_sitearch}/barmodule/

Using this macro instead of hardcoding the directory in the specfile ensures your spec remains compatible with the installed Node.js version even if the directory structure changes radically (for instance, if %nodejs_sitelib moves into %{_datadir}).

Using tarballs from the npm registry

The canonical method for shipping most node modules is tarballs from the npm registry. The Source0 for such modules should be of the form http://registry.npmjs.org/<modulename>/-/<modulename>-<version>.tgz. For instance:

Source0:  http://registry.npmjs.org/npm/-/npm-1.1.70.tgz

This method should be preferred to using checkouts from git or automatically generated tarballs from GitHub.

These tarballs store the contents of the module inside a package directory, so every package using these tarballs should use the following in %prep:

%prep
%setup -q -n package
Idea.png
Verifying hashes
The SHA1SUM of tarballs delivered by the npm registry is available as the dist['shasum'] JSON property of the npm metadata for the module, which can be obtained by visiting http://registry.npmjs.org/<modulename>/<version>

Installing Modules

Most node modules do not contain their own install mechanism. Instead they rely on npm to do it for them. npm must not be used to install modules in Fedora packages, since it usually requires network access, always tries to bundle libraries, and installs files in a manner inconsistent with the Filesystem Hierarchy Standard (FHS).

Instead, install files in their proper place manually using install or cp. Most files should be installed in %{nodejs_sitelib}/<npm module name><code> but documentation should be installed via <code>%doc. In the event that the module ships arch independent content other than JavaScript code, that content should be installed in %{_datadir} and the module should be patched to cope with that.

Client-side JavaScript

Many node modules contain JavaScript that can be used both client-side and server-side and it is sometimes hard to identify code intended only for use in the browser. Since there are no current packaging guidelines for client-side JavaScript and bundling of such code is currently permitted in Fedora, it is currently permissible for client-side JavaScript to be bundled with nodejs modules in %{nodejs_sitelib}.

Note.png
These exceptions will probably go away.
With the introduction of Node.js into Fedora it is likely that standards for client-side JavaScript will be established and the bundling exception for client-side JavaScript will be removed. Many client-side JavaScript technologies use node in some way or use node modules as the canonical method of distribution (sometimes alongside code intended to be used with node) so such guidelines must certainly take Node.js into account. At this time, node module packages will be expected to conform to these guidelines, possibly shipping the client-side and server-side portions separately.

Automatic Requires and Provides

The nodejs package includes an automatic Requires and Provides generator that automatically adds versioned dependencies based on the information provided in a module's package.json file.

Provides

It also adds virtual provides in the form npm(<module name>) to identify modules listed in the npm registry (the module is listed at npmjs.org) . If a module is not listed in the npm registry, it must not provide this. Modules that aren't listed in the npm registry should set private to true in their package.json file. If not, you must patch package.json to include that.

Correcting Dependencies

Occasionally the dependencies listed in package.json are inaccurate. For instance, the module may work with a newer version of a dependency than the one explictly listed in the package.json file. To make correcting such dependencies easier, the %nodejs_fixdep macro is provided. This macro should be used in %prep and will patch package.json to contain the correct dependency information.

Warning (medium size).png
Always fix package.json
RPM macros like %nodejs_symlink_deps rely on accurate information in package.json to work properly, as does the Node.js interpreter and npm at runtime.

To convert any dependency to not list a specific version, just call %nodejs_fixdep with the npm module name of the dependency. This changes the version in package.json to *. (Or adds one if it wasn't already listed.) For example:

%prep
%setup -q -n package
%nodejs_fixdep foomodule

You can also specify a version:

%prep
%setup -q -n package
%nodejs_fixdep foomodule '>2.0'

The second argument to %nodejs_fixdep must be a valid package.json version specifier as explained in `man npm json`.

You can also remove a dependency:

%prep
%setup -q -n package
%nodejs_fixdep -r foomodule
Important.png
Notify upstream
You should always send patches or bugs upstream when correcting dependencies.

Symlinking Dependencies

Node.js and npm require that dependencies explicitly be included or linked into a node_modules directory inside the module directory. To make this easier, a %nodejs_symlink_deps macro is provided and will automatically create a node_modules tree with symlinks for each dependency listed in package.json. This macro should be called in the %install section of every Node.js module package.

Note.png
Include even in modules without dependencies
While it isn't strictly necessary in modules that don't have dependencies, include it anyway so you don't have to worry about adding it if the package adds dependencies in the future.

Removing bundled modules

Some node modules contain copies of other libraries in their source tree. You must remove these in %prep. Simply running rm -rf node_modules is sufficient for most modules.

%nodejs_symlink_deps outputs a warning when a node_modules directory already exists in the %buildroot, and will fail if it cannot create a symlink because a directory for it already exists.

Building native modules with node-gyp

Most native modules use the node-gyp tool to build themselves, which configures and uses the gyp build framework to build addon modules that can interact with Node.js and the V8 JavaScript interpreter used by it.

The WAF build framework has been abandoned by upstream and is not supported in Fedora.

BuildRequires

To build a native module designed to be built with node-gyp, add BuildRequires: node-gyp, along with BuildRequires: nodejs-devel and -devel packages for any shared libraries needed by the module.

 %build

Some native modules have Makefiles or other build processes that handle any special needs that module has, such as linking to system versions of dependencies. If present, these should be used. Check the module's package.json file for information about what command npm will run to build these modules.

Most modules use vanilla node-gyp, and may not have build instructions in package.json. To build these, simply use the following:

%build
export CXXFLAGS="%{optflags}"
node-gyp rebuild

Note that some modules may specify something like node-gyp configure && node-gyp build. This is equivalent to node-gyp rebuild.

 %install

node-gyp creates a shared object file conventionally named <module name>.node as part of its build process, which should be located in build/Release. This file may be used as the main entry point for the library, or is utilized by JavaScript wrapper code included with the module.

If the shared object is used as the main entry point, it should be installed at %{nodejs_sitelib}/<module name>/<module_name>.node. The `require()` function will automatically load this if there is no corresponding `<module name>.js` or entry point defined in package.json to override it. For example:

%install
mkdir -p %{buildroot}%{nodejs_sitelib}/foomodule
cp -p build/Release/foomodule.node package.json %{buildroot}%{nodejs_sitelib}/foomodule/

If the shared object is called by JavaScript wrapper code, the situation is slightly more complicated.

If the module uses the npm bindings module, the shared object file should be installed in %{nodejs_sitelib}/<module name>/build/<module name>.node, which is at the top of bindings' search path and where node-gyp usually creates a symlink to wherever the real shared object file exists. For example:

%install
mkdir -p %{buildroot}%{nodejs_sitelib}/foomodule/build
cp -p package.json wrapper.js %{buildroot}%{nodejs_sitelib}/foomodule/
cp -p build/Release/foomodule.node %{buildroot}%{nodejs_sitelib}/foomodule/build/

If the module hardcodes build/Release/<module name>.node, the module should be patched to use build/<module name>.node instead, and upstream should be advised that they should use the bindings module, because their module could break when users use debug builds of node.

If the module uses it's own Makefiles to locate the shared object file(s) to a specific location, then those files should installed in that location.

Note.png
Don't install unnecessary development files
npm will leave C++ source files, object (.o) files, etc. in the module directory after installing it. These files must not be installed in Fedora packages.

Dealing with Bundled Libraries

Many native modules contain bundled copies of libraries already present in Fedora. You must build against the system version of these libraries. For more information, see Packaging:No Bundled Libraries.

The Fedora version of node-gyp will handle the fact that shared versions of libuv, v8, and http_parser without modification to the module, since node-gyp always unconditionally configures these libraries. However, some modules may rely on other libraries bundled with node, such as openssl or c-ares. These may need to be patched to use the system headers for these libraries.

Questionmark.png
Could we have an example srpm?
This section looks okay but without an example to look at it we can't check whether this is okay very easily. Do you have a package that we could review?