Add a CI job to test ce-upgrade-ee migration path

We're not trying to reuse the commands here because:

* Avoid touching CE tasks
* Allow them to evolve independently if needed
* It's nice to have highlighted command lines history

.gitlab-ci.yml

@@ -338,6 +338,25 @@ stages:
     - date
     - bundle exec rake db:migrate
 
+.migration-paths-upgrade-ce-to-ee: &migration-paths-upgrade-ce-to-ee
+  <<: *dedicated-no-docs-and-no-qa-pull-cache-job
+  variables:
+    CREATE_DB_USER: "true"
+  script:
+    - CE_HEAD=$(ruby -r./scripts/ee_specific_check/ee_specific_check -e'puts EESpecificCheck.fetch_remote_ce_branch')
+    - git checkout -f $CE_HEAD
+    - bundle install $BUNDLE_INSTALL_FLAGS
+    - date
+    - cp config/gitlab.yml.example config/gitlab.yml
+    - bundle exec rake db:drop db:create db:schema:load db:seed_fu
+    - date
+    - git checkout $CI_COMMIT_SHA
+    - bundle install $BUNDLE_INSTALL_FLAGS
+    - date
+    - . scripts/prepare_build.sh
+    - date
+    - bundle exec rake db:migrate
+
 ##
 # Trigger a package build in omnibus-gitlab repository
 #
@@ -738,6 +757,14 @@ migration:path-mysql:
   <<: *migration-paths
   <<: *use-mysql
 
+migration:upgrade-pg-ce-to-ee:
+  <<: *migration-paths-upgrade-ce-to-ee
+  <<: *use-pg
+
+migration:upgrade-mysql-ce-to-ee:
+  <<: *migration-paths-upgrade-ce-to-ee
+  <<: *use-mysql
+
 .db-rollback: &db-rollback
   <<: *dedicated-no-docs-and-no-qa-pull-cache-job
   script:

scripts/ee_specific_check/ee_specific_check.rb

@@ -23,14 +23,12 @@ module EESpecificCheck
   end
 
   def say(message)
-    puts "\n#{message}", "\n" # puts would eat trailing newline
+    warn "\n#{message}", "\n" # puts would eat trailing newline
   end
 
   def find_compare_base
     git_clean
 
-    setup_canonical_remotes
-
     ce_fetch_head = fetch_remote_ce_branch
     ce_fetch_base = run_git_command("merge-base canonical-ce/master #{ce_fetch_head}")
     ce_merge_base = run_git_command("merge-base canonical-ce/master canonical-ee/master")
@@ -57,6 +55,8 @@ module EESpecificCheck
   end
 
   def fetch_remote_ce_branch
+    setup_canonical_remotes
+
     remote_to_fetch, branch_to_fetch = find_remote_ce_branch
 
     run_git_command("fetch #{remote_to_fetch} #{branch_to_fetch} --quiet")
@@ -220,7 +220,7 @@ module EESpecificCheck
 
   def run_command(*commands)
     commands.map do |cmd|
-      puts "=> Running `#{cmd}`"
+      warn "=> Running `#{cmd}`"
 
       `#{cmd}`.strip
     end