[chef] Re: Gem install on Ubuntu 12

[Bryan McLellan < >]

On Mon, Jul 23, 2012 at 12:29 AM, Steve Bennett 
<
 >
 wrote:
> I ran into an issue a couple of days ago with the default (omnibus?)
> chef-client install on Ubuntu 12.04. Basically, it somehow ends up with two
> versions of Gems (or just Ruby? - I'm not a Ruby person) installed, in
> different locations: Gems 1.8 in /var/lib/gems, and 1.9.1 somewhere else
> (/opt/...something...chef-embedded I think). The upshot of this was that a
> cookbook that worked on Ubuntu 10.04 didn't work - a postgres gem ("pg")
> installed, but couldn't be found by a later step that required it. It was
> present, but not available to the ruby environment in use at the time.

This is by design. Omnibus Chef ships with its own version of Ruby. It
is stable for running Chef, but should never be used for any other
purpose. You can choose to not have a system ruby installed at all if
you wish. You can install your Ruby using rvm, rbenv, or any other
magic you want, and it won't bother Chef's own version of Ruby.

> People on IRC helped with a workaround: installing chef-client with the
> specific distribution, "-d ubuntu12.04".

This particular template installs Chef under the system's Rubygems,
which is installed as a package from upstream. This is perfectly fine
as long as that's the version of Ruby you want to use for everything
else you do with ruby, provided of course that you do something else
with Ruby besides running Chef.

On Mon, Jul 23, 2012 at 12:48 AM, Morgan Blackthorne
<
 >
 wrote:
> I think the thing is, if you want to run Chef with Ubuntu 12, you want to
> switch the default version of ruby away from ruby1.8. So you'd want to do
> "update-alternatives --config ruby" to point the default to ruby1.9 (and
> associated binaries such as "gem", "ri", "rdoc", etc.).

Chef runs fine with Ruby 1.8. Future versions of Debian and Ubuntu
will have not only a newer Ruby, but a nicer redesign of the packaging
scheme for managing Ruby libraries and different versions of the Ruby
API.

On Mon, Jul 23, 2012 at 4:05 AM, Steve Bennett 
<
 >
 wrote:
>
> Should gem_package be deprecated, then?

In the course of developing the Omnibus installer we realized that the
gem_package provider was being used for two different use cases; one
for installing a gem to your system to use, such as rails to run a web
service, and the other to install a gem to use in Chef recipes, such
as the mysql gem to connect to a database and modify it. Thus, we
created chef_gem in CHEF-2879 [1].

gem_package should be used in cookbooks when you want to install a gem
to your system for use outside of Chef. Since we don't know what Ruby
is your system Ruby, we use the Ruby that Chef is running under unless
you specify otherwise with the gem_binary attribute. However, under
Omnibus, we know that you're running Chef under the copy of Ruby that
ships with Omnibus and that it is not your system ruby, so we walk
your path in search of a ruby binary.

chef_gem should be used in cookbooks when you want to use a gem in a
chef recipe. It will install a gem immediately, which means in the
compilation phase of cookbook processing so the gem will be available
when you run other Ruby code (outside of a ruby block resource) in
your cookbook. You cannot change which gem binary this provider uses
because it always uses the Ruby that Chef is running under. This
provider does all the magic that you used to have to add to
gem_package to do this, such as running Gem.clear_paths. This is
simpler and reduces code duplication.

That the postgresql cookbook is broken under omnibus is a known bug
filed under COOK-1406 [2]. This is a somewhat unique issue such that
the postgres gem compiles extensions which use openssl and Omnibus has
its own copy of openssl. There are other dependencies required to
compile the postgresql extension which are installed to the system
using packages. However those packages are compiled against a
difference version of openssl than is included with Omnibus. It is not
trivial to prevent the Rubygems included with omnibus to not include
that version of openssl when compiling. I've done some testing with
this and talked to some of the folks smarter than me at Opscode and we
don't see a better path forward than compiling those bits from source
inside of Omnibus. The postgresql cookbook will be updated to do so.

-- 
Bryan McLellan | opscode | technical program manager, open source
(c) 206.607.7108 | (t) @btmspox | (b) http://blog.loftninjas.org

[1] http://tickets.opscode.com/browse/CHEF-2879
[2] http://tickets.opscode.com/browse/COOK-1406