Improve handling of postgresql['version'] in pg-upgrade

* Don't exit 1 if it is set
* Clarify the language when it is found

changelogs/unreleased/4969-add-postgresql-11-x-as-a-third-database-version.yml

+---
+title: Add PostgreSQL 11 as an alpha database version
+merge_request: 3858
+author:
+type: other

config/patches/postgresql_alpha/no_docs.patch

+--- GNUmakefile.in.original     2016-12-19 06:01:36.664961781 -0500
++++ GNUmakefile.in      2016-12-19 06:02:15.872961781 -0500
+@@ -16,7 +16,7 @@
+ docs:
+        $(MAKE) -C doc all
+
+-$(call recurse,world,doc src config contrib,all)
++$(call recurse,world,src config contrib,all)
+ world:
+        +@echo "PostgreSQL, contrib, and documentation successfully made. Ready to install."
+
+@@ -32,7 +32,7 @@
+ install-docs:
+        $(MAKE) -C doc install
+
+-$(call recurse,install-world,doc src config contrib,install)
++$(call recurse,install-world,src config contrib,install)
+ install-world:
+        +@echo "PostgreSQL, contrib, and documentation installation complete."

config/software/gitlab-rails.rb

@@ -43,6 +43,7 @@ dependency 'rsync'
 dependency 'libicu'
 dependency 'postgresql'
 dependency 'postgresql_new'
+dependency 'postgresql_alpha'
 dependency 'python-docutils'
 dependency 'krb5'
 dependency 'registry'

config/software/postgresql_alpha.rb

+#
+# Copyright 2012-2014 Chef Software, Inc.
+# Copyright:: Copyright (c) 2016 GitLab Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+name 'postgresql_alpha'
+default_version '11.6'
+
+license 'PostgreSQL'
+license_file 'COPYRIGHT'
+
+skip_transitive_dependency_licensing true
+
+dependency 'zlib'
+dependency 'openssl'
+dependency 'libedit'
+dependency 'ncurses'
+dependency 'libossp-uuid'
+dependency 'config_guess'
+
+version '11.6' do
+  source sha256: '49924f7ff92965fdb20c86e0696f2dc9f8553e1563124ead7beedf8910c13170'
+end
+
+# PostgreSQL 10 and up should have a major version of 10, not 10.0.
+# See: https://www.postgresql.org/support/versioning
+#
+# Be sure to update files/gitlab-cookbooks/postgresql/recipes/enable.rb when
+# upgrading.
+major_version = '11'
+
+source url: "https://ftp.postgresql.org/pub/source/v#{version}/postgresql-#{version}.tar.bz2"
+
+relative_path "postgresql-#{version}"
+
+build do
+  env = with_standard_compiler_flags(with_embedded_path)
+  prefix = "#{install_dir}/embedded/postgresql/#{major_version}"
+  update_config_guess(target: 'config')
+
+  patch source: 'no_docs.patch', target: 'GNUmakefile.in'
+
+  command './configure' \
+          " --prefix=#{prefix}" \
+          ' --with-libedit-preferred' \
+          ' --with-openssl' \
+          ' --with-ossp-uuid', env: env
+
+  make "world -j #{workers}", env: env
+  make 'install-world', env: env
+end
+
+# exclude headers and static libraries from package
+project.exclude "embedded/bin/pg_config"
+project.exclude "embedded/postgresql/#{major_version}/include"
+project.exclude "embedded/postgresql/#{major_version}/lib/*.a"
+project.exclude "embedded/postgresql/#{major_version}/lib/pgxs"
+project.exclude "embedded/postgresql/#{major_version}/lib/pkgconfig"

files/gitlab-ctl-commands/pg-upgrade.rb

@@ -89,6 +89,15 @@ add_command_under_category 'pg-upgrade', 'database',
     Kernel.exit 0
   end
+  unless GitlabCtl::Util.progress_message(
+    "Checking if postgresql['version'] is set"
+  ) do
+    @attributes['postgresql']['version'].nil?
+  end
+    log "postgresql['version'] is set in /etc/gitlab/gitlab.rb. Not checking for a PostgreSQL upgrade"
+    Kernel.exit 0
+  end
+
   log 'Checking for a newer version of PostgreSQL to install'
   if upgrade_version && Dir.exist?("#{INST_DIR}/#{upgrade_version.major}")
     log "Upgrading PostgreSQL to #{upgrade_version}"
@@ -116,15 +125,6 @@ add_command_under_category 'pg-upgrade', 'database',
     Kernel.exit 1
   end
-  unless GitlabCtl::Util.progress_message(
-    "Checking if postgresql['version'] is set"
-  ) do
-    @attributes['postgresql']['version'].nil?
-  end
-    log "postgresql['version'] is set in /etc/gitlab/gitlab.rb. Please remove this and run gitlab-ctl reconfigure before proceeding "
-    Kernel.exit 1
-  end
-
   # The current instance needs to be running, start it if it isn't
   unless @db_worker.running?
     log 'Starting the database'