Custom package provider to work around namespace conflicts - ruby

Question

I have a set of RHEL / CentOS systems where I am using the NetBSD pkgsrc system
to install various packages into a certain tree (e.g. /opt/local). I want to
manage this with Puppet. I started out simply using the pkgin provider, but
I quickly ran into namespace conflicts. For example, both the yum and pkgin
providers were adding Package[openssl], and they conflicted.
To fix this, I have been trying to use a static prefix on my pkgsrc packages,
then strip it off when it is actually passed to the pkgin command for handling.
First, I wrote a define to add the prefix and set the provider.
define mypkgin::package($ensure='latest') {
package { "mypkgin_${title}":
ensure => $ensure,
provider => 'mypkgin',
}
}
This will show up in the namespace as Mypkgin::Package[openssl], which does
not itself conflict with anything. And its goal is to add a resource named
Package[mypkgin_openssl], to not conflict with Package[openssl] from yum.
Then, I copied the pkgin provider code and modified it to provide a thing
named mypkgin. I have a small method in here to strip the prefix from the
name, and that is used in a few places so that the pkgin command receives
the pkgsrc package name instead of the prefixed version.
require "puppet/provider/package"
Puppet::Type.type(:package).provide :mypkgin, :parent => Puppet::Provider::Package do
desc "Package management using pkgin/pkgsrc, my local edition."
# Specify full path since it's not in Puppet's exec path
commands :pkgin => "/opt/local/bin/pkgin"
has_feature :installable, :uninstallable, :upgradeable, :versionable
# Strip prefix off of package name
def my_pkgname(package)
package.gsub(/^mypkgin_/, '')
end
def self.parse_pkgin_line(package)
# e.g.
# vim-7.2.446 = Vim editor (vi clone) without GUI
match, name, version, status = *package.match(/(\S+)-(\S+)(?: (=|>|<))?\s+.+$/)
if match
{
:name => name,
:status => status,
:ensure => version
}
end
end
def self.prefetch(packages)
super
# Without -f, no fresh pkg_summary files are downloaded
pkgin("-yf", :update)
end
def self.instances
pkgin(:list).split("\n").map do |package|
new(parse_pkgin_line(package))
end
end
def query
packages = parse_pkgsearch_line
if packages.empty?
if #resource[:ensure] == :absent
notice "declared as absent but unavailable #{#resource.file}:#{resource.line}"
return false
else
#resource.fail "No candidate to be installed"
end
end
packages.first.update( :ensure => :absent )
end
def parse_pkgsearch_line
packages = pkgin(:search, my_pkgname(resource[:name])).split("\n")
return [] if packages.length == 1
packages.slice!(-4, 4)
pkglist = packages.map{ |line| self.class.parse_pkgin_line(line) }
pkglist.select{ |package| my_pkgname(resource[:name]) == package[:name] }
end
def install
if String === #resource[:ensure]
pkgin("-y", :install, "#{my_pkgname(resource[:name])}-#{resource[:ensure]}")
else
pkgin("-y", :install, my_pkgname(resource[:name]))
end
end
def uninstall
pkgin("-y", :remove, my_pkgname(resource[:name]))
end
def latest
package = parse_pkgsearch_line.detect{ |package| package[:status] == '<' }
return properties[:ensure] if not package
return package[:ensure]
end
def update
pkgin("-y", :install, my_pkgname(resource[:name]))
end
end
Every time I run puppet agent --test, it tells me that it has added all of these
packages. So clearly I have some namespace bit wrong. It thinks on each run that
the package either needs to be installed, or upgraded, and it tries to do that.
I assume that in one or more places, I should add or remove calls to
my_pkgname(), but I can't seem to figure out where I've gone wrong.

Answer 1

Your provider determines which packages are already available on the system by means of prefetching. It looks like you have not replaced or overridden the bits that will result in that process ultimately relying on the instances() method.
Looking at that method, it appears that it will generate instances exactly as the pkgin provider would do, right down to the generated package names. That's a problem for you, because your scheme involves translating package names. It's not enough just to translate the names Puppet uses to the native ones -- you must also translate the native ones to the ones you want Puppet to see when you create instances on the provider side.
It looks like self.parse_pkgin_line() could be modified pretty easily to prepend the needed prefix to your package names. That seems like it would be the right thing for it to do, but I'm uncertain whether it would have any undesirable side effects. It is possible that additional changes will be required as well, such as in parse_pkgsearch_line(), but that's not immediately clear to me.