cache: support etcd3gw backend

This change introduces support to use ectd3gw backend as oslo.cache
backend, and makes the required backend package installed. The same
backend is already supported for coordination and this change leverage
the existing definitions added for coordination.

Change-Id: Id0eec018a68ab4a510307f150aa2a6ee017fa651

manifests/cache.pp

@@ -210,6 +210,12 @@ define oslo::cache(
         name   => $::oslo::params::python_memcache_package_name,
         tag    => ['openstack'],
       })
+    } elsif ($backend =~ /\.etcd3gw/ ) {
+      ensure_packages('python-etcd3gw', {
+        name   => $::oslo::params::python_etcd3gw_package_name,
+        ensure => $package_ensure,
+        tag    => 'openstack',
+      })
     }
   }
 

spec/defines/oslo_cache_spec.rb

@@ -165,6 +165,51 @@ describe 'oslo::cache' do
       end
     end
 
+    context 'with etcd3gw backend' do
+      let :params do
+        {
+          :backend => 'oslo_cache.etcd3gw',
+        }
+      end
+
+      it 'configures cache backend' do
+        is_expected.to contain_keystone_config('cache/backend').with_value('oslo_cache.etcd3gw')
+        is_expected.to contain_package('python-etcd3gw').with(
+          :ensure => 'present',
+          :name   => platform_params[:python_etcd3gw_package_name],
+          :tag    => ['openstack'],
+        )
+      end
+
+      context 'with package_ensure set' do
+        before do
+          params.merge!({
+            :package_ensure => 'latest'
+          })
+        end
+
+        it 'ensures status of the package' do
+          is_expected.to contain_package('python-etcd3gw').with(
+            :ensure => 'latest',
+            :name   => platform_params[:python_etcd3gw_package_name],
+            :tag    => 'openstack',
+          )
+        end
+      end
+
+      context 'with backend package management disabled' do
+        before do
+          params.merge!({
+            :manage_backend_package => false,
+          })
+        end
+
+        it 'does not install backend package' do
+          is_expected.not_to contain_package('python-etcd3gw')
+        end
+      end
+    end
+
     context 'with string in list parameters' do
       let :params do
         {
@@ -194,10 +239,12 @@ describe 'oslo::cache' do
         case facts[:osfamily]
         when 'Debian'
           { :pylibmc_package_name         => 'python3-pylibmc',
-            :python_memcache_package_name => 'python3-memcache' }
+            :python_memcache_package_name => 'python3-memcache',
+            :python_etcd3gw_package_name  => 'python3-etcd3gw' }
         when 'RedHat'
           { :pylibmc_package_name         => 'python3-pylibmc',
-            :python_memcache_package_name => 'python3-memcached' }
+            :python_memcache_package_name => 'python3-memcached',
+            :python_etcd3gw_package_name  => 'python3-etcd3gw' }
         end
       end