From 6142ac364892e0617fc87398d3e9eebde5254788 Mon Sep 17 00:00:00 2001
From: "Moritz Grosch (LittleFox)" <littlefox@lf-net.org>
Date: Fri, 8 Sep 2017 08:42:40 +0200
Subject: [PATCH] Added perl environment (#311)

Perl runtime environment and example function.
---
 environments/perl/Dockerfile |  9 +++++++
 environments/perl/README.md  | 30 +++++++++++++++++++++++
 environments/perl/server.pl  | 46 ++++++++++++++++++++++++++++++++++++
 examples/perl/hello.pm       | 18 ++++++++++++++
 4 files changed, 103 insertions(+)
 create mode 100644 environments/perl/Dockerfile
 create mode 100644 environments/perl/README.md
 create mode 100755 environments/perl/server.pl
 create mode 100644 examples/perl/hello.pm

diff --git a/environments/perl/Dockerfile b/environments/perl/Dockerfile
new file mode 100644
index 00000000..12e67ce6
--- /dev/null
+++ b/environments/perl/Dockerfile
@@ -0,0 +1,9 @@
+FROM perl:latest
+
+RUN cpanm -n Twiggy Getopt::Args Dancer2
+
+COPY    server.pl /server.pl
+WORKDIR /
+
+EXPOSE 8888
+ENTRYPOINT ["/server.pl"]
diff --git a/environments/perl/README.md b/environments/perl/README.md
new file mode 100644
index 00000000..d7704c3b
--- /dev/null
+++ b/environments/perl/README.md
@@ -0,0 +1,30 @@
+# Fission Perl environment
+
+This is an environment to execute perl code.
+
+It is implemented using the lightweight web application framework
+[Dancer2](https://metacpan.org/pod/Dancer2) and the async I/O webserver
+[Twiggy](https://metacpan.org/pod/Twiggy).
+
+Since Twiggy is implemented with [AnyEvent](https://metacpan.org/pod/AnyEvent),
+you can write async code using AnyEvent in your function.
+
+## Usage
+
+The function you upload is actually a perl package returning a coderef (see the
+example).
+
+You can use other packages and add more subs, but only the coderef you returned
+from the package is executed directly.
+
+Your main-function gets exactly one argument: the Dancer2 request object. You
+may want to `use Dancer2` to get functions like `send_error`.
+
+## Example
+
+```perl
+# hello.pm
+return sub {
+    return 'Hello, Perl!';
+}
+```
diff --git a/environments/perl/server.pl b/environments/perl/server.pl
new file mode 100755
index 00000000..1145f998
--- /dev/null
+++ b/environments/perl/server.pl
@@ -0,0 +1,46 @@
+#!/usr/bin/env perl
+
+use utf8;
+use strict;
+use warnings;
+
+use Getopt::Args;
+use Plack::Handler::Twiggy;
+
+opt codepath => (
+    isa     => 'Str',
+    default => '/userfunc/user',
+    comment => 'Path to the user code',
+);
+
+opt port => (
+    isa     => 'Int',
+    default => 8888,
+    comment => 'Port to listen on',
+);
+
+my $options = optargs();
+
+{
+    package App::Fission::Perl;
+
+    use Dancer2;
+
+    our $userfunc;
+
+    post '/specialize' => sub {
+        if($userfunc) {
+            send_error('Not a generic container', 400);
+        }
+
+        $userfunc = require($options->{codepath});
+        return '';
+    };
+
+    any '/' => sub {
+        return $userfunc ? $userfunc->(request) : send_error('Not yet specialized', 500);
+    };
+}
+
+my $handler = Plack::Handler::Twiggy->new(port => $options->{port});
+$handler->run(App::Fission::Perl->to_app);
diff --git a/examples/perl/hello.pm b/examples/perl/hello.pm
new file mode 100644
index 00000000..0710a26b
--- /dev/null
+++ b/examples/perl/hello.pm
@@ -0,0 +1,18 @@
+=pod
+
+You return a CODEREF from the package that will be called as your function.
+
+The code in the server is something like this (simplified):
+
+    my $sub = require('hello.pm');
+    $sub->(request);
+
+As you can see, you get the L<Dancer2::Core::Request> object as first argument
+to your function. You can use it to retrieve params given to your function or
+anything else Dancer2 offers. You can also use Dancer2 and use its DSL.
+
+=cut
+
+return sub {
+    return 'Hello, ' . (shift->param('name') // 'world');
+};