Allow setting of synchronous replication settings

This adds support for setting "synchronous_commit" and
"synchronous_standby_names" in PostgreSQL. These settings can be used to
enable and control synchronous replication behaviour.

CHANGELOG.md

@@ -10,6 +10,8 @@ are not the same (O Schwede) 62b5cc
 8.17.0
+- Add support for setting PostgreSQL's synchronous_commit and
+  synchronous_standby_names settings
 - Remove deprecated Elasticsearch configuration options ab660c56
 - Include GitLab Pages in the Community Edition
 - Add HealthCheck support to our Docker image 845b52b2

files/gitlab-config-template/gitlab.rb.template

@@ -611,6 +611,8 @@ external_url 'GENERATED_EXTERNAL_URL'
 # postgresql['max_standby_archive_delay'] = "30s"
 # postgresql['max_standby_streaming_delay'] = "30s"
 # postgresql['max_replication_slots'] = 0
+# postgresql['synchronous_commit'] = on
+# postgresql['synchronous_standby_names'] = ''
 # Backup/Archive settings
 # default['gitlab']['postgresql']['archive_mode'] = "off"

files/gitlab-cookbooks/gitlab/attributes/default.rb

@@ -411,6 +411,8 @@ default['gitlab']['postgresql']['hot_standby'] = "off"
 default['gitlab']['postgresql']['max_standby_archive_delay'] = "30s"
 default['gitlab']['postgresql']['max_standby_streaming_delay'] = "30s"
 default['gitlab']['postgresql']['max_replication_slots'] = 0
+default['gitlab']['postgresql']['synchronous_commit'] = 'on'
+default['gitlab']['postgresql']['synchronous_standby_names'] = ''
 # Backup/Archive settings
 default['gitlab']['postgresql']['archive_mode'] = "off"

files/gitlab-cookbooks/gitlab/templates/default/postgresql.conf.erb

@@ -161,7 +161,8 @@ shared_preload_libraries = '<%= node['gitlab']['postgresql']['shared_preload_lib
 wal_level = <%= node['gitlab']['postgresql']['wal_level'] %>
           # (change requires restart)
 #fsync = on       # turns forced synchronization on or off
-#synchronous_commit = on    # synchronization level; on, off, or local
+synchronous_commit = <%= node['gitlab']['postgresql']['synchronous_commit'] %> # synchronization level; on, off, or local
+synchronous_standby_names = '<%= node['gitlab']['postgresql']['synchronous_standby_names'] %>'
 #wal_sync_method = fsync    # the default is the first option
           # supported by the operating system:
           #   open_datasync

spec/chef/recipes/postgresql_spec.rb

@@ -209,6 +209,24 @@ describe 'postgresql 9.6' do
       ).with_content(/max_replication_slots = 0/)
     end
+    it 'sets the synchronous_commit setting' do
+      expect(chef_run.node['gitlab']['postgresql']['synchronous_commit'])
+        .to eq('on')
+
+      expect(chef_run).to render_file(
+        '/var/opt/gitlab/postgresql/data/postgresql.conf'
+      ).with_content(/synchronous_commit = on/)
+    end
+
+    it 'sets the synchronous_commit setting' do
+      expect(chef_run.node['gitlab']['postgresql']['synchronous_standby_names'])
+        .to eq('')
+
+      expect(chef_run).to render_file(
+        '/var/opt/gitlab/postgresql/data/postgresql.conf'
+      ).with_content(/synchronous_standby_names = ''/)
+    end
+
     context 'running version differs from data version' do
       before do
         allow_any_instance_of(PgHelper).to receive(:version).and_return('9.2.18')