nixpkgs manual: Add documentation for bower2nix

Fixes #9459
Fixes #13214

2 files changed, 262 insertions, 0 deletions

diff --git a/doc/languages-frameworks/bower.xml b/doc/languages-frameworks/bower.xml
new file mode 100644
index 00000000000..742d3c2e9fe
--- /dev/null
+++ b/doc/languages-frameworks/bower.xml
@@ -0,0 +1,244 @@
+<section xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xml:id="sec-bower">
+
+<title>Bower</title>
+
+<para>
+  <link xlink:href="http://bower.io">Bower</link> is a package manager
+  for web site front-end components. Bower packages (comprising of
+  build artefacts and sometimes sources) are stored in
+  <command>git</command> repositories, typically on Github. The
+  package registry is run by the Bower team with package metadata
+  coming from the <filename>bower.json</filename> file within each
+  package.
+</para>
+
+<para>
+  The end result of running Bower is a
+  <filename>bower_components</filename> directory which can be included
+  in the web app's build process.
+</para>
+
+<para>
+  Bower can be run interactively, by installing
+  <varname>nodePackages.bower</varname>. More interestingly, the Bower
+  components can be declared in a Nix derivation, with the help of
+  <varname>nodePackages.bower2nix</varname>.
+</para>
+
+<section xml:id="ssec-bower2nix-usage">
+  <title><command>bower2nix</command> usage</title>
+
+<para>
+  Suppose you have a <filename>bower.json</filename> with the following contents:
+
+
+<example xml:id="ex-bowerJson"><title><filename>bower.json</filename></title>
+<programlisting language="json">
+<![CDATA[{
+  "name": "my-web-app",
+  "dependencies": {
+    "angular": "~1.5.0",
+    "bootstrap": "~3.3.6"
+  }
+}]]>
+</programlisting>
+</example>
+</para>
+
+
+<para>
+  Running <command>bower2nix</command> will produce something like the
+  following output:
+
+<programlisting language="nix">
+<![CDATA[{ fetchbower, buildEnv }:
+buildEnv { name = "bower-env"; ignoreCollisions = true; paths = [
+  (fetchbower "angular" "1.5.3" "~1.5.0" "1749xb0firxdra4rzadm4q9x90v6pzkbd7xmcyjk6qfza09ykk9y")
+  (fetchbower "bootstrap" "3.3.6" "~3.3.6" "1vvqlpbfcy0k5pncfjaiskj3y6scwifxygfqnw393sjfxiviwmbv")
+  (fetchbower "jquery" "2.2.2" "1.9.1 - 2" "10sp5h98sqwk90y4k6hbdviwqzvzwqf47r3r51pakch5ii2y7js1")
+]; }]]>
+</programlisting>
+</para>
+
+
+<para>
+  Using the <command>bower2nix</command> command line arguments, the
+  output can be redirected to a file. A name like
+  <filename>bower-packages.nix</filename> would be fine.
+</para>
+
+<para>
+  The resulting derivation is a union of all the downloaded Bower
+  packages (and their dependencies). To use it, they still need to be
+  linked together by Bower, which is where
+  <varname>buildBowerComponents</varname> is useful.
+</para>
+</section>
+
+<section xml:id="ssec-build-bower-components"><title><varname>buildBowerComponents</varname> function</title>
+
+  <para>
+  The function is implemented in <link xlink:href="https://github.com/NixOS/nixpkgs/blob/master/pkgs/development/bower-modules/generic/default.nix">
+  <filename>pkgs/development/bower-modules/generic/default.nix</filename></link>.
+  Example usage:
+
+<example xml:id="ex-buildBowerComponents"><title>buildBowerComponents</title>
+<programlisting language="nix">
+bowerComponents = buildBowerComponents {
+  name = "my-web-app";
+  generated = ./bower-packages.nix; <co xml:id="ex-buildBowerComponents-1" />
+  src = myWebApp; <co xml:id="ex-buildBowerComponents-2" />
+};
+</programlisting>
+</example>
+  </para>
+
+<para>
+In <xref linkend="ex-buildBowerComponents" />, the following arguments
+are of special significance to the function:
+
+<calloutlist>
+  <callout arearefs="ex-buildBowerComponents-1">
+    <para>
+      <varname>generated</varname> specifies the file which was created by <command>bower2nix</command>.
+    </para>
+  </callout>
+
+  <callout arearefs="ex-buildBowerComponents-2">
+    <para>
+      <varname>src</varname> is your project's sources. It needs to
+      contain a <filename>bower.json</filename> file.
+    </para>
+  </callout>
+</calloutlist>
+</para>
+
+<para>
+  <varname>buildBowerComponents</varname> will run Bower to link
+  together the output of <command>bower2nix</command>, resulting in a
+  <filename>bower_components</filename> directory which can be used.
+</para>
+
+<para>
+  Here is an example of a web frontend build process using
+  <command>gulp</command>. You might use <command>grunt</command>, or
+  anything else.
+</para>
+
+<example xml:id="ex-bowerGulpFile"><title>Example build script (<filename>gulpfile.js</filename>)</title>
+<programlisting language="javascript">
+<![CDATA[var gulp = require('gulp');
+
+gulp.task('default', [], function () {
+  gulp.start('build');
+});
+
+gulp.task('build', [], function () {
+  console.log("Just a dummy gulp build");
+  gulp
+    .src(["./bower_components/**/*"])
+    .pipe(gulp.dest("./gulpdist/"));
+});]]>
+</programlisting>
+</example>
+
+<example xml:id="ex-buildBowerComponentsDefaultNix">
+  <title>Full example — <filename>default.nix</filename></title>
+<programlisting language="nix">
+{ myWebApp ? { outPath = ./.; name = "myWebApp"; }
+, pkgs ? import &lt;nixpkgs&gt; {}
+}:
+
+pkgs.stdenv.mkDerivation {
+  name = "my-web-app-frontend";
+  src = myWebApp;
+
+  buildInputs = [ pkgs.nodePackages.gulp ];
+
+  bowerComponents = pkgs.buildBowerComponents { <co xml:id="ex-buildBowerComponentsDefault-1" />
+    name = "my-web-app";
+    generated = ./bower-packages.nix;
+    src = myWebApp;
+  };
+
+  buildPhase = ''
+    cp --reflink=auto --no-preserve=mode -R $bowerComponents/bower_components . <co xml:id="ex-buildBowerComponentsDefault-2" />
+    export HOME=$PWD <co xml:id="ex-buildBowerComponentsDefault-3" />
+    ${pkgs.nodePackages.gulp}/bin/gulp build <co xml:id="ex-buildBowerComponentsDefault-4" />
+  '';
+
+  installPhase = "mv gulpdist $out";
+}
+</programlisting>
+</example>
+
+<para>
+A few notes about <xref linkend="ex-buildBowerComponentsDefaultNix" />:
+
+<calloutlist>
+  <callout arearefs="ex-buildBowerComponentsDefault-1">
+    <para>
+      The result of <varname>buildBowerComponents</varname> is an
+      input to the frontend build.
+    </para>
+  </callout>
+
+  <callout arearefs="ex-buildBowerComponentsDefault-2">
+    <para>
+      Whether to symlink or copy the
+      <filename>bower_components</filename> directory depends on the
+      build tool in use. In this case a copy is used to avoid
+      <command>gulp</command> silliness with permissions.
+    </para>
+  </callout>
+
+  <callout arearefs="ex-buildBowerComponentsDefault-3">
+    <para>
+      <command>gulp</command> requires <varname>HOME</varname> to
+      refer to a writeable directory.
+    </para>
+  </callout>
+
+  <callout arearefs="ex-buildBowerComponentsDefault-4">
+    <para>
+      The actual build command. Other tools could be used.
+    </para>
+  </callout>
+</calloutlist>
+</para>
+</section>
+
+<section xml:id="ssec-bower2nix-troubleshooting">
+  <title>Troubleshooting</title>
+
+<variablelist>
+
+  <varlistentry>
+    <term>
+    <literal>ENOCACHE</literal> errors from
+    <varname>buildBowerComponents</varname>
+    </term>
+    <listitem>
+      <para>
+        This means that Bower was looking for a package version which
+        doesn't exist in the generated
+        <filename>bower-packages.nix</filename>.
+      </para>
+      <para>
+        If <filename>bower.json</filename> has been updated, then run
+        <command>bower2nix</command> again.
+      </para>
+      <para>
+        It could also be a bug in <command>bower2nix</command> or
+        <command>fetchbower</command>. If possible, try reformulating
+        the version specification in <filename>bower.json</filename>.
+      </para>
+    </listitem>
+  </varlistentry>
+</variablelist>
+
+</section>
+
+</section>
diff --git a/doc/languages-frameworks/index.xml b/doc/languages-frameworks/index.xml
index ab62afa40d6..63c4b7dec60 100644
--- a/doc/languages-frameworks/index.xml
+++ b/doc/languages-frameworks/index.xml
@@ -24,6 +24,24 @@ such as Perl or Haskell.  These are described in this chapter.</para>
 <xi:include href="r.xml" /> <!-- generated from ../../pkgs/development/r-modules/README.md  -->
 <xi:include href="qt.xml" />
 <xi:include href="texlive.xml" />
+<xi:include href="bower.xml" />
+
+
+<!--
+<section><title>Haskell</title>
+
+<para>TODO</para>
+
+</section>
+
+
+<section><title>TeX / LaTeX</title>
+
+<para>* Special support for building TeX documents</para>
+
+</section>
+-->
+>>>>>>> 05113a5... nixpkgs manual: Add documentation for bower2nix
 
 
 </chapter>