sqlalchemy: Ensure backend package is installed

Some of the backends supported by sqlalchemy (eg mysql + pymysql)
require additional packages. This ensures the required packages are
installed using the oslo::db defined type.

Change-Id: I7fc4cea95a0a7ecba7def9db4f01c16ef1cfa2f3

manifests/management/sqlalchemy.pp

@@ -3,8 +3,13 @@
 # [*uri*]
 #   SQLAlchemy Connection URI. Required.
 #
+# [*package_ensure*]
+#   (Optional) Ensure state for package.
+#   Defaults to present.
+#
 class zaqar::management::sqlalchemy(
   $uri,
+  $package_ensure = 'present',
 ) {
 
   include zaqar::deps
@@ -13,4 +18,9 @@ class zaqar::management::sqlalchemy(
     'drivers:management_store:sqlalchemy/uri': value => $uri, secret => true;
   }
 
+  oslo::db { 'zaqar_config':
+    connection             => $uri,
+    backend_package_ensure => $package_ensure,
+    manage_config          => false,
+  }
 }

releasenotes/notes/sqlalchemy-package-3ac8b214e19bb380.yaml

@@ -0,0 +1,6 @@
+---
+features:
+  - |
+    The ``zaqar::management::sqlalchemy`` class now ensures the dependent
+    library packages such as PyMySQL is installed. The package's state can be
+    customized using the new ``package_ensure`` parameter.

spec/classes/zaqar_management_sqlalchemy_spec.rb

@@ -30,6 +30,10 @@ describe 'zaqar::management::sqlalchemy' do
         is_expected.to contain_zaqar_config('drivers:management_store:sqlalchemy/uri').with(
          :value => 'mysql://user:pass@127.0.0.1/zaqar',
         )
+        is_expected.to contain_oslo__db('zaqar_config').with(
+          :connection             => 'mysql://user:pass@127.0.0.1/zaqar',
+          :backend_package_ensure => 'present'
+        )
       end
 
     end