Cooking Perl with Chef - Grant Report #2

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David Golden reported:

Current progress

Three of the eight deliverables are complete:

  1. Publish a Chef cookbook for Perl interpreter deployment
  2. Publish a Chef cookbook for CPAN module deployment
  3. Publish a Chef cookbook for Plack application deployment

These have been uploaded to the Opscode Community Cookbooks site in two separate cookbook distributions:

perlbrew

The perlbrew cookbook satisfies deliverables #1 and #2. It provides several "lightweight resource providers" (LWRPs -- a Chef term) that use perlbrew to deliver various automation capabilities:
  • perlbrew_perl -- installs a perl from source to a user-configurable directory (by default, "/opt/perlbrew/perls/")
  • perlbrew_lib -- establishes a local::lib style directory for use with a particular perlbrew perl
  • perlbrew_cpanm -- installs CPAN modules into a perlbrew perl or local::lib
  • perlbrew_run -- runs arbitrary bash commands in the context of a particular perlbrew perl or local::lib

For example, this snippet of ruby could be used in a recipe to install a perl, configure a library, install some CPAN modules to the library, and then run a perl command using that perl and library:

include_recipe 'perlbrew'

perlbrew_lib 'perl-5.8.9@xdg'

perlbrew_cpanm "Stuff we need" do perlbrew 'perl-5.8.9@xdg' modules ['Data::UUID::MT', 'Data::GUID::Any'] end

perlbrewrun "print a UUID" do perlbrew 'perl-5.8.9@xdg' command "perl -MData::GUID::Any -le 'print Data::GUID::Any::guidas_string'" end

carton

The carton cookbook satisfies deliverable #3. It provides an LWRP called 'carton_app' that uses carton to install application-specific dependencies into a application-local directory and then sets up the application as a system service using runit.

For example, this snippet of ruby could be used in a recipe to launch a carton-based application from a deployment directory. Note that most of the application-specific attributes are parameterized using Chef's 'node' data structure for each deployment node, making it easy to change how the application is deployed to different servers:

include_recipe 'carton'

cartonapp "hello-world" do perlbrew node['hello-world']['perlversion'] command "starman -p #{node['hello-world']['port']} app.psgi" cwd node['hello-world']['deploy_dir'] user node['hello-world']['user'] group node['hello-world']['group'] end

carton_app "hello-world" do action :start end

Current work and next steps

I have started refactoring the initial draft of pantry to make it easier to configure nodes without requiring users to edit JSON directly (deliverable #4). This will let me streamline the tutorials and help users following the tutorial to avoid introducing JSON errors and getting stuck.

Next month I expect to finish and publish the hello-world tutorial (deliverable #5) and have a (rough) draft of the "real world" tutorial (deliverable #6).

I was pleased to hear that my OSCON proposal was accepted and my Cooking Perl with Chef talk will be on Thursday, July 19. That presentation will satisfy deliverable #7 (though I may deliver a draft early as a test run). If I find out that my OSCON session will be videotaped, I'll use that as the video tutorial (deliverable #8). If not, I'll prepare a separate screen cast. (I may do both and use the short screencast as part of the talk to avoid the risk of a live demo.)

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About this Entry

This page contains a single entry by Alan Haggai Alavi published on April 23, 2012 2:41 AM.

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