db: Remove MongoDB backend support

Support for MongoDB backend was used by puppet-ceilometer but it is
no longer used since MongoDB was replaced by Gnocchi.

Because we no longer expect any real use case, this change removes
the implementation directly with deprecation skipped.

Change-Id: I5203cefe77c6c1410842fa7c530f98761fe65ed4

manifests/db.pp

@@ -156,7 +156,7 @@ define oslo::db(
   if !is_service_default($connection) {
 
     validate_legacy(Oslo::Dbconn, 'validate_re', $connection,
-      ['^(sqlite|mysql(\+pymysql)?|postgresql(\+psycopg2)?|mongodb):\/\/(\S+:\S+@\S+\/\S+)?'])
+      ['^(sqlite|mysql(\+pymysql)?|postgresql(\+psycopg2)?):\/\/(\S+:\S+@\S+\/\S+)?'])
 
     if $manage_backend_package {
       case $connection {
@@ -173,9 +173,6 @@ define oslo::db(
           $backend_package = false
           require 'postgresql::lib::python'
         }
-        /^mongodb:\/\//: {
-          $backend_package = $::oslo::params::pymongo_package_name
-        }
         /^sqlite:\/\//: {
           $backend_package = $::oslo::params::sqlite_package_name
         }

manifests/params.pp

@@ -5,7 +5,6 @@
 class oslo::params {
   include openstacklib::defaults
 
-  $pymongo_package_name = 'python3-pymongo'
   $pylibmc_package_name = 'python3-pylibmc'
 
   case $::osfamily {

releasenotes/notes/remove-mongo-01c0895a76175bb4.yaml

@@ -0,0 +1,4 @@
+---
+upgrade:
+  - |
+    The ``oslo::db`` defined resource type no longer supports MongoDB backend.

spec/defines/oslo_db_spec.rb

@@ -78,41 +78,6 @@ describe 'oslo::db' do
       end
     end
 
-    context 'with mongodb backend' do
-      let :params do
-        { :connection => 'mongodb://localhost:1234/db' }
-      end
-
-      it 'install the proper backend package' do
-        is_expected.to contain_package(platform_params[:pymongo_package_name]).with(
-          :ensure => 'present',
-          :name   => platform_params[:pymongo_package_name],
-          :tag    => 'openstack'
-        )
-      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-pymongo')
-        end
-      end
-    end
-
-    context 'with specific mongodb connection string' do
-      let :params do
-        { :connection => 'mongodb://user:password@host1:27017,host2:27017,host3:27017/db_name?replicaSet=replica&readPreference=primaryPreferred' }
-      end
-
-      it { is_expected.to contain_keystone_config('database/connection').with_value(
-        'mongodb://user:password@host1:27017,host2:27017,host3:27017/db_name?replicaSet=replica&readPreference=primaryPreferred').with_secret(true) }
-    end
-
     context 'with pymysql connection' do
       let :params do
         { :connection => 'mysql+pymysql://db:db@localhost/db' }