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Carton 1.0 managing CPAN deps the right way Tatsuhiko Miyagawa @miyagawa O'Reilly OSCON 2013 Wednesday, July 24, 13

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Me • Tatsuhiko Miyagawa • Lives in San Francisco • {github,twitter,CPAN}/miyagawa Wednesday, July 24, 13

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Managing CPAN Dependencies Wednesday, July 24, 13

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How many CPAN modules your app depends on? Wednesday, July 24, 13

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When is the last time upgrading a CPAN module broke your app? Wednesday, July 24, 13

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Case Study: Web App Development Wednesday, July 24, 13

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You’re writing a new web app using as many CPAN modules. Wednesday, July 24, 13

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Get them from CPAN, install on your machine. Wednesday, July 24, 13

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john@local>  cpanm  Web::Framework installed  LWP-­‐5.912 installed  Plack-­‐0.9980 installed  Web-­‐Framework-­‐1.10 Wednesday, July 24, 13

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Test it... Wednesday, July 24, 13

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Works? Ship it! Wednesday, July 24, 13

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What if ... Wednesday, July 24, 13

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• Jul 2nd: Started working on project • using Web::Framework 1.1 • Jul 9th: Finished version 1.0 • Jul 10-15th: internal beta, QA • Jul 16th: Deploy to the production Wednesday, July 24, 13

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• Jul 2nd: Started working on project • using Web::Framework 1.1 • Jul 9th: Finished version 1.0 • Jul 10-15th: internal beta, QA • Jul 15th: Web::Framework 1.2 is released • Jul 16th: Deploy to the cloud/production Wednesday, July 24, 13

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root@prod>  cpanm  Web::Framework installed  LWP-­‐5.912 installed  Plack-­‐0.9980 installed  Web-­‐Framework-­‐1.20 Wednesday, July 24, 13

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Web::Framework 1.2 API changes! Wednesday, July 24, 13

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Wednesday, July 24, 13

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Wednesday, July 24, 13

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“Upgrading CPAN modules broke my app” Wednesday, July 24, 13

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Dependencies are part of your app. Wednesday, July 24, 13

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a solution cpanm 1.6 Wednesday, July 24, 13

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>  cpanm  Web::Framework@1.10 installed  Web-­‐Framework-­‐1.10 Wednesday, July 24, 13

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>  cpanm  Web::Framework~">=  1.0,  <  1.2" installed  Web-­‐Framework-­‐1.19 Wednesday, July 24, 13

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♥ MetaCPAN Wednesday, July 24, 13

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a solution cpanfile + cpanm 1.6 Wednesday, July 24, 13

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>  cat  cpanfile requires  'Web::Framework',  '==  1.10'; >  cpanm  -­‐-­‐installdeps  . installed  Web-­‐Framework-­‐1.10 Wednesday, July 24, 13

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cpanfile DSL to describe prereqs Wednesday, July 24, 13

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requires  'Catalyst',  '5.8000';   recommends  'JSON::XS',  '2.0'; on  'test'  =>  sub  {    requires  'Test::More',  '>=  0.96' }; on  'develop'  =>  sub  {    recommends  'Devel::NYTProf'; }; feature  'sqlite'  =>  sub  {    requires  'DBD::SQLite'; }; Wednesday, July 24, 13

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inspired by: gemfile(5) Wednesday, July 24, 13

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Backward compatible to: Module::Install(::DSL) Wednesday, July 24, 13

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Converted to to: CPAN::Meta::Prereqs Wednesday, July 24, 13

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Toolset Module::CPANfile Module::Install::CPANfile Dist::Zilla plugins Wednesday, July 24, 13

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Supported by dzil, Milla & cpanm 1.6 Wednesday, July 24, 13

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cpanfile + cpanm • Simple • Yet powerful and flexible way to describe dependencies and version requirements • Version control cpanfile Wednesday, July 24, 13

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caveats • Locking each dependency with specific version is tedious work • Can only lock direct dependencies • MetaCPAN as SPOF • No easy/reliable way to fallback Wednesday, July 24, 13

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Many other solutions Needs servers, Needs databases Too simple, Too complicated, etc. Wednesday, July 24, 13

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the Solution Wednesday, July 24, 13

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Carton https://github.com/miyagawa/carton Wednesday, July 24, 13

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Inspired by... Wednesday, July 24, 13

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Wednesday, July 24, 13

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Basic idea: Describe CPAN dependencies snapshot tarball pathnames Wednesday, July 24, 13

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Built on top of: cpanfile + cpanm 1.6 Wednesday, July 24, 13

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• App-specific local environment • Fast and safe install with caches • Dep-tree analysis, including versions • Freezing module versions • Conservative updates • Easy Redeployment, Rollback • Single-file, VCS friendly Wednesday, July 24, 13

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Local perl environment Using local::lib and cpanm -L Each app has an isolated local library path Wednesday, July 24, 13

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Fast and safe install Saves MYMETA.json and install meta info Wednesday, July 24, 13

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Dep tree analysis Rebuild the dependency tree from snapshot Checks if anything is missing/superfluous Wednesday, July 24, 13

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Freezing versions Versions are saved in snapshots including dependencies Wednesday, July 24, 13

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Easy Redeployment Reinstall exactly the same set of modules on another prod/development machines. Wednesday, July 24, 13

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Conservative Update Modules won't be upgraded unless it is required, or manually updated. Wednesday, July 24, 13

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Single-file, VCS friendly You can add cpanfile.snapshot to git update whenever you update modules "Dependencies are part of your app." Wednesday, July 24, 13

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Safe and easy rollback revert the lock file and redeploy Wednesday, July 24, 13

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DEMO Wednesday, July 24, 13

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Deployment with Carton Wednesday, July 24, 13

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 @local>  carton  install  @local>  git  commit  cpanfile.snapshot  @local>  git  push @remote>  carton  install  -­‐-­‐deployment @remote>  carton  exec  plackup  ... Wednesday, July 24, 13

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Example: github.com/miyagawa/cpanmetadb-perl capistrano, Server::Starter, carton, plackup (twiggy) Wednesday, July 24, 13

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PaaS/Cloud github.com/miyagawa/heroku-buildpack-perl Wednesday, July 24, 13

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Wednesday, July 24, 13

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http://weblog.bulknews.net Wednesday, July 24, 13

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Support to come! Dokku, DotCloud, Travis CI, Cloud Foundry etc. Wednesday, July 24, 13

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carton 1.0 later this week Wednesday, July 24, 13

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>  cpanm  -­‐-­‐dev  Carton Wednesday, July 24, 13

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Towards 1.1 • Inject patched versions (DarkPAN) • Install from github • bootstrap with fatpack Wednesday, July 24, 13

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github.com/miyagawa/carton irc.perl.org #carton Wednesday, July 24, 13

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speakerdeck.com /miyagawa Wednesday, July 24, 13

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Questions? Wednesday, July 24, 13