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@@ -31,7 +31,7 @@
background: none !important;
border: none !important;
box-shadow: none !important;
- font-size: 0.45em !important;
+ font-size: 0.4em !important;
}
.caption {
@@ -71,15 +71,16 @@
<h1>Perl software in<br>GNU Guix</h1>
<aside class="notes" data-markdown>
- Hello, my name is Chris, and I'm talking about package
- management with GNU Guix.
+ Hello, my name is Chris, and I'm talking about GNU Guix
+ and Perl, mostly Guix.
- I first found out about Guix sometime in late 2015, early
- 2016.
+ You might know Perl, it's a very established programming
+ language.
- I remember installing it the night before FOSDEM back in
- 2016 and I started using and contributing to Guix soon
- after.
+ GNU Guix is a more recent project, it started in
+ 2012. It's a package manager, and distribution of the GNU
+ system.
+ </aside>
</section>
<section>
@@ -89,6 +90,20 @@
<p>Get and use Perl modules</p>
<p>Get and use tools and applications written in Perl</p>
+
+ <aside class="notes" data-markdown>
+ Perl is an important component for Guix as a package
+ manager, as many other packages depend on Perl at build
+ time, or runtime.
+
+ It's also something Guix can help you use. If you want to
+ run Perl, you can use Guix to install it.
+
+ Guix also packages some Perl (around 700) modules.
+
+ There's also software packaged for Guix that's written in
+ Perl, and I'll mention a couple of examples.
+ </aside>
</section>
<section>
@@ -96,12 +111,20 @@
<pre>→ guix install perl
+...
+
→ perl --version
This is perl 5, version 28, subversion 0 (v5.28.0) built for
x86_64-linux-thread-multi
...</pre>
+
+ <aside class="notes" data-markdown>
+ Back to getting Perl though. Installing packages through
+ Guix is quite simple, you can run the `guix install`
+ command with the name of the package.
+ </aside>
</section>
<section>
@@ -110,11 +133,31 @@ x86_64-linux-thread-multi
<pre>
→ guix install perl perl-uri
+...
+
→ echo $PERL5LIB
/gnu/store/h3ryiwyhp8qcxyf74sxyv746171zpazr-profile/lib/perl5/site_perl
→ ls /gnu/store/h3r...azr-profile/lib/perl5/site_perl/5.28.0/
URI URI.pm x86_64-linux-thread-multi</pre>
+
+ <aside class="notes" data-markdown>
+ Installing Perl with some modules is very similar.
+
+ Note here that these modules have to be specifically
+ packaged for Guix, more about that later.
+
+ If you're familiar with other distributions that use a
+ more standard filesystem hierarchy, Guix isn't like that.
+
+ Most things end up in the `/gnu/store` directory. Guix
+ however, does understand that Perl uses the PERL5LIB
+ environment variable to find things within the `lib/perl5/site_perl`
+ directory within packages, so when it creates a profile, a
+ grouping together of packages, it'll group the Perl
+ modules together, and include the appropriate value for
+ the `PERL5LIB` environment variable.
+ </aside>
</section>
<section data-background="white">
@@ -125,6 +168,18 @@ URI URI.pm x86_64-linux-thread-multi</pre>
<li>Static site generator</li>
<li>I occasionally use it for blogging</li>
</ul>
+
+ <aside class="notes" data-markdown>
+ On to some software that's written in Perl.
+
+ Ikiwiki is a wiki compiler, built around a flexible static
+ site generator. I personally use it for simple websites
+ and blogs.
+
+ It's written in Perl, and I was using it before I started
+ using Guix. It was also absent from Guix back then, so I
+ packaged it, and some of it's missing dependencies.
+ </aside>
</section>
<section>
@@ -146,6 +201,14 @@ in repository guix.
new f0539b6 gnu: Add perl-cgi-session.
new 909dcf5 gnu: Add ikiwiki.
</pre>
+
+ <aside class="notes" data-markdown>
+ I don't want to spend too much time on this, but I thought
+ it might be useful to skim over the Guix package
+ definition for Ikiwiki. It's too long to fit on one slide,
+ but hopefully this'll give you an idea of what goes in to
+ a Guix package.
+ </aside>
</section>
<section>
@@ -163,12 +226,37 @@ in repository guix.
(sha256
(base32
<span class="string">"17pyblaqhkb61lxl63bzndiffism8k859p54k3k4sghclq6lsynh"</span>))))</span>
-<span class="fragment fade-in">...</span>
-</pre></section>
+ <span class="fragment fade-in">...</span></pre>
+
+ <aside class="notes" data-markdown>
+ Packages in Guix are defined through a record type in
+ Guile scheme. I've only done a little bit of Perl
+ programming, but I think it has a concept of a record as
+ well.
+
+ So, `define-public ikiwiki` is defining a value called
+ `ikiwiki`, which is a package.
+
+ (next)
+
+ Next there are some fields in the package record. The
+ package has a name, and the version is also specified.
+
+ (next)
+
+ Then the `source` is defined. This says to fetch something
+ from a URL. In this case, the Ikiwiki package is a little
+ odd. Normally this would be a release tarball from the
+ upstream authors, not the snapshot.debian.org site.
+
+ Importantly, the expected hash of the file is also
+ specified. This means there'll be no surprises, and that
+ the behaviour will be consistent in to the future.
+ </aside>
+ </section>
<section>
- <pre>
-<span style="opacity: 0.5;">(<span class="yellow-keyboard">define-public</span> ikiwiki
+ <pre><span style="opacity: 0.5;">(<span class="yellow-keyboard">define-public</span> ikiwiki
(package</span>
...
<span class="fragment fade-in-then-semi-out">(build-system perl-build-system)</span>
@@ -199,7 +287,40 @@ in repository guix.
`(<span class="string">"PERL5LIB"</span> <span class="string">":"</span> prefix (,path))))
(find-files bin))
#t))))))</span>
-<span class="fragment fade-in">...</span></pre></section>
+ <span class="fragment fade-in">...</span></pre>
+
+ <aside class="notes" data-markdown>
+ Moving on, each package has a build system. There are
+ quite a few build systems, each representing common build
+ steps that apply to multiple packages.
+
+ In this case, Ikiwiki uses the perl-build-system. This
+ will look for files like Build.PL and Makefile.PL, and use
+ them if they exist.
+
+ (next)
+
+ The build system can be passed some arguments. Here, some
+ of the phases of the build process are being tweaked.
+
+ (next)
+
+ After the `'unpack` phase, there's a small change being
+ made to the source code. The value of the PERL5LIB
+ environment variable is being included in a file. This is
+ so Ikiwiki can find the modules it requires at runtime.
+
+ (next)
+
+ The Makefile is then patched to have the example
+ configuration installed. Often this isn't necessary.
+
+ Finally, one common step is wrapping the files within the
+ bin directory with the value of the PERL5LIB environment
+ variable. This is also to ensure that Ikiwiki can find the
+ modules it requires at runtime.
+ </aside>
+ </section>
<section>
<pre><span style="opacity: 0.5;">(<span class="yellow-keyboard">define-public</span> ikiwiki
@@ -231,7 +352,46 @@ in repository guix.
(<span class="string">"perl-text-markdown-discount"</span> ,perl-text-markdown-discount)
(<span class="string">"perl-uri"</span> ,perl-uri)
(<span class="string">"perl-yaml-libyaml"</span> ,perl-yaml-libyaml)))</span>
-<span class="fragment fade-in">...</span></pre></section>
+ <span class="fragment fade-in">...</span></pre>
+
+ <aside class="notes" data-markdown>
+ Next come the inputs to the package.
+
+ The terminology comes from the "functional" package
+ management paradigm that Guix uses. If you consider a
+ building a package a function, the dependencies are inputs
+ to that function, and the output of the function is the
+ built package in the store.
+
+ There are multiple types of inputs, native-inputs are
+ those that are just used at build time. Whereas inputs are
+ used at runtime, and maybe also when the package is being
+ built.
+
+ The distinction is mostly important when cross compiling,
+ something which the Perl build system doesn't currently
+ support as far as I'm aware.
+
+ Thinking back to the use of the PERL5LIB environment
+ variable on the previous slide, these are the modules
+ which will be mentioned in the value of that environment
+ variable.
+
+ When building a Guix package, the build process takes
+ place in an isolated environment, with only the store
+ items that the package and build system explicitly
+ require, along with their dependnecies.
+
+ Guix will ensure that any store item referenced by the
+ generated outputs exists within the store. Which it's why
+ it's important for the Ikiwiki package to reference the
+ modules it requires explicitly.
+
+ This is similar to what other package managers do with the
+ notion of dependencies, except in Guix it's much more
+ specific and unchanging.
+ </aside>
+ </section>
<section>
<pre><span style="opacity: 0.5;">(<span class="yellow-keyboard">define-public</span> ikiwiki
@@ -243,8 +403,13 @@ in repository guix.
<span class="string">"Ikiwiki is a wiki compiler, capable of generating a static set of web
pages, but also incorporating dynamic features like a web based editor and
commenting."</span>)
- (license license:gpl2+)))</span>
- </pre>
+ (license license:gpl2+)))</span></pre>
+
+<aside class="notes" data-markdown>
+ Moving on, the last few fields within the package record are some
+ metadata, the home page, and license for the package, along with a
+ short synopsis and longer description.
+</aside>
</section>
<section>
@@ -255,6 +420,20 @@ commenting."</span>)
<span class="fragment fade-right">/gnu/store/hcrv2cqzbisdb35hg2xmbxp1r2z7ijzd-ikiwiki-3.20190228</span>
</pre>
+
+ <aside class="notes" data-markdown>
+ With this definition, we can instruct Guix to build the
+ Ikiwiki package.
+
+ Stuff may happen, then you should see the store item that
+ has been created.
+
+ The hash here in the name represents the process that's
+ gone in to creating this package. Including all the
+ inputs, the build system and the arguments in the package
+ definition. Change any of that, the hash will change, and
+ you'll get a different store item.
+ </aside>
</section>
<section>
@@ -291,10 +470,28 @@ commenting."</span>)
└── man8
└── ikiwiki-mass-rebuild.8.gz
</pre>
+
+ <aside class="notes" data-markdown>
+ While Guix doesn't follow the same filesystem hierachy as
+ other distributions of GNU, what you find within the store
+ item for a package might be more familiar. Particularly
+ the bin, lib and share directories.
+
+ (Any questions about Ikiwiki?)
+ </aside>
</section>
<section data-background="white">
<img src="sqitch-logo.svg" alt="Sqitch" style="width: 15em;" />
+
+ <ul>
+ <li>Sensible database change management</li>
+ </ul>
+
+ <aside class="notes" data-markdown>
+ Next, I thought I'd mention Sqitch. It's a database change
+ management tool that I've recently started using.
+ </aside>
</section>
<section>
@@ -320,6 +517,13 @@ in repository guix.
new 55916fa gnu: Add perl-mysql-config.
new 7b23313 gnu: Add perl-string-shellquote.
new cabe8f1 gnu: Add sqitch.</pre>
+
+ <aside class="notes" data-markdown>
+ It's written in Perl, and I recently packaged it for
+ Guix. The process and package definition is similar to
+ Ikiwiki, this time, let's look at packaging one of the
+ missing modules required by Sqitch.
+ </aside>
</section>
<section>
@@ -352,6 +556,20 @@ From http://www.cpan.org/authors/id/M/MI/MIYAGAWA/HTTP-Tinyish-0.15.tar.gz...
<span class="string">"HTTP::Tiny compatible HTTP client wrappers"</span>)
(description fill-in-yourself!)
(license perl-license))</pre>
+
+ <aside class="notes" data-markdown>
+ Guix has several importers. These importers utilise the
+ information that already exists about packages to help
+ creating Guix package definitions.
+
+ In this case, the information from CPAN is used to fill in
+ some of the parts of the perl-http-tinyish package
+ definition.
+
+ Importers can make it much easier to create package
+ definitions for Perl modules, as well as lots of other
+ languages.
+ </aside>
</section>
<section>
@@ -361,6 +579,12 @@ From http://www.cpan.org/authors/id/M/MI/MIYAGAWA/HTTP-Tinyish-0.15.tar.gz...
<p>Get and use Perl modules</p>
<p>Get and use tools and applications written in Perl</p>
+
+ <aside class="notes" data-markdown>
+ So to recap, I haven't gone much in to the more general
+ what and why around Guix, but hopefully some of these Perl
+ examples have been useful.
+ </aside>
</section>
</div>
</div>