How to use App::FatPacker effectively

Yokohama\.(pm6?|go) #14 2016.03.18
(original https://www.slideshare.net/skaji/how-to-use-appfatpacker-effectively)

Transcript

1. How to use App::FatPacker effectively Shoichi Kaji
2. About Me • Shoichi Kaji • CPAN SKAJI • perl5 cpm, App::FatPacker::Simple, Mojo::SlackRTM • perl6 mi6, Frinfon
3. Contents • What is App::FatPacker? • Who uses App::FatPacker? • How to use App::FatPacker • Problems and solutions for App::FatPacker • Conclusion • See also
4. What is App::FatPacker?
5. • Let’s say you want to download perl tarball. • This script runs perfectly in your local OS X. # download.pl use strict; use warnings; use HTTP::Tiny; my $http = HTTP::Tiny->new; my $url = "http://www.cpan.org/src/5.0/perl-5.22.1.tar.gz"; my $res = $http->mirror($url => "perl-5.22.1.tar.gz"); if ($res->{success}) { warn "Complete!\n"; } else { die "Failed $res->{status}"; }
6. • But, if you run it in a remote CentOS6 host, you’ll get • This is because the perl in CentOS6 is so old that it does not have HTTP::Tiny in core :/ $ /usr/bin/perl download.pl Can’t locate HTTP/Tiny.pm in @INC (@INC contains…)
7. What can we do? • Yes, we can install HTTP::Tiny in remote host • But it is sometimes tiresome, or even impossible. • Okay let’s introduce App::FatPacker by mst now! $ cpanm HTTP::Tiny Successfully installed HTTP-Tiny-0.056
8. • App::FatPacker embeds HTTP::Tiny into a BEGIN block so that we have self-contailed download.pl # download.fatpack.pl BEGIN { my %fatpacked; $fatpacked{"HTTP/Tiny.pm"} = <<'EOF'; package HTTP::Tiny; # ... all HTTP::Tiny code ... 1; EOF my $class = "FatPacked::" . (0+\%fatpacked); *{$class . "::INC"} = sub { my ($self, $pm) = @_; if (my $content = $self->{$pm}) { open my $fh, "<", \$content; return $fh; } return; }; unshift @INC, bless \%fatpacked, $class; } # content of download.pl...
9. $ /usr/bin/perl download.fatpack.pl Complete!
10. 😄
11. Who uses App::FatPacker? • perlbrew by gugod • cpanm by miyagawa • perl-build (plenv plugin) by tokuhirom • start_server (bundled in h2o) by kazuho
12. How to use App::FatPacker • perldoc fatpack says: # 1. trace dependencies fatpack trace myscript.pl # 2. find .packlist files fatpack packlists-for `cat fatpacker.trace` >packlists # 3. collect pm files in ./fatlib directory fatpack tree `cat packlists` # 4. bundles all pm files in ./fatlib into BEGIN block of myscript.pl fatpack file myscript.pl >myscript.packed.pl
13. Problem • I cannot remember usage of fatpack :/ • Tracing dependencies may result in unexpected • Modules that I want to trace does not trace • Modules that I do not want to trace trace
14. Solution • I created App::FatPacker::Simple • It completely leaves you to trace dependencies • It just creates a fatpacked script with all modules in lib, local, fatlib, extlib directories
15. • It is simple, isn’t it? # You know HTTP::Tiny is a dependency. # So install it to ./local first $ cpanm -nq -L ./local HTTP::Tiny Successfully installed HTTP-Tiny-0.056 # Then just run fatpack-simple $ fatpack-simple download.pl -> fatpack HTTP/Tiny.pm (with perl-strip) -> Successfully created download.fatpack.pl
16. Still problem… • Although I said App::FatPacker::Simple leaves you to trace dependencies, it’s sometimes annoying. • Let’s say your script depends on URI module. Then $ cpanm -nq -L ./local URI Successfully installed URI-1.71 $ fatpack-simple script.pl -> Successfully created script.fatpack.pl $ /path/to/5.8.5/perl script.fatpack.pl Can’t locate parent.pm in @INC ...
17. • Solutions might be • Use perl5.8.5 even in fatpacking process💩 • Use cpm with --target-perl option👍 $ cpm install --target-perl 5.8.5 URI DONE install parent-0.234 DONE install URI-1.71 $ fatpack-simple script.pl -> Successfully created script.fatpack.pl $ /path/to/5.8.5/perl script.fatpack.pl # WORKS!
18. Conclusion • App::FatPacker can create a self-contained, depencency-free perl script • App::FatPacker::Simple + cpm may help that • Happy hacking with perl5!
19. See also • https://metacpan.org/pod/App::FatPacker • https://metacpan.org/pod/App::FatPacker::Simple • https://github.com/skaji/plenv-download (a real example of using fatpack-simple + cpm) • http://ks0608.hatenablog.com/entry/ 2015/06/07/004313 (an explanation of require() function, in japanese)