(PUP-4198) Add install_options feature to pip provider

Add support for passing in additional options to pip install. The
current provider has no way to send additional options to pip.

For example, there are cases where you may want to connect to a
different package index, or add an extra index url to look for packages.
In my use case, we maintained our own pre-built wheels and wanted to
connect only to our pypi index and not to the general index at all, so
--find-links and --no-index achieve this.

Author: butlern

lib/puppet/provider/package/pip.rb

@@ -7,9 +7,13 @@
 Puppet::Type.type(:package).provide :pip,
   :parent => ::Puppet::Provider::Package do
 
-  desc "Python packages via `pip`."
+  desc "Python packages via `pip`.
 
-  has_feature :installable, :uninstallable, :upgradeable, :versionable
+  This provider supports the `install_options` attribute, which allows command-line flags to be passed to pip.
+  These options should be specified as a string (e.g. '--flag'), a hash (e.g. {'--flag' => 'value'}),
+  or an array where each element is either a string or a hash."
+
+  has_feature :installable, :uninstallable, :upgradeable, :versionable, :install_options
 
   # Parse lines of output from `pip freeze`, which are structured as
   # _package_==_version_.
@@ -71,6 +75,7 @@ def latest
   # gives the fully-qualified URL to the repository.
   def install
     args = %w{install -q}
+    args +=  install_options if @resource[:install_options]
     if @resource[:source]
       if String === @resource[:ensure]
         args << "#{@resource[:source]}@#{@resource[:ensure]}#egg=#{
@@ -115,4 +120,8 @@ def lazy_pip(*args)
       raise e, 'Could not locate the pip command.', e.backtrace
     end
   end
+
+  def install_options
+    join_options(@resource[:install_options])
+  end
 end

spec/unit/provider/package/pip_spec.rb

@@ -193,6 +193,15 @@
       @provider.install
     end
 
+    it "should handle install options" do
+      @resource[:ensure] = :installed
+      @resource[:source] = nil
+      @resource[:install_options] = [{"--timeout" => "10"}, "--no-index"]
+      @provider.expects(:lazy_pip).
+        with("install", "-q", "--timeout=10", "--no-index", "fake_package")
+      @provider.install
+    end
+
   end
 
   describe "uninstall" do