Check the target branch when pulling upstream projects

2 files changed, 45 insertions, 30 deletions

diff --git a/lib/tasks/build_site.rake b/lib/tasks/build_site.rake
index 9d32bbf9..7b1fdadf 100644
--- a/lib/tasks/build_site.rake
+++ b/lib/tasks/build_site.rake
@@ -21,7 +21,7 @@ task :clone_repositories do
       && branch == ENV['CI_DEFAULT_BRANCH'] \
       && ENV["CI_PIPELINE_SOURCE"] == 'pipeline'
 
-    puts "\n#{TaskHelpers::COLOR_CODE_GREEN}INFO: Cloning #{product['repo']}..#{TaskHelpers::COLOR_CODE_RESET}"
+    puts "\n#{TaskHelpers::COLOR_CODE_GREEN}INFO: Cloning branch '#{branch}' of #{product['repo']}..#{TaskHelpers::COLOR_CODE_RESET}"
 
     #
     # Handle the cases where we land on a runner that already ran a docs build,
diff --git a/lib/tasks/task_helpers.rb b/lib/tasks/task_helpers.rb
index bf5e54ac..fd64afe6 100644
--- a/lib/tasks/task_helpers.rb
+++ b/lib/tasks/task_helpers.rb
@@ -28,38 +28,32 @@ class TaskHelpers
   end
 
   def retrieve_branch(slug)
-    # If CI_COMMIT_REF_NAME is not defined (run locally), set it to the default branch.
-    if ENV["CI_COMMIT_REF_NAME"].nil?
-      default_branch(products[slug].fetch('repo'))
-
-    # If we're on a gitlab-docs stable branch according to the regex, catch the
-    # version and assign the product stable branches correctly.
-    elsif version = ENV["CI_COMMIT_REF_NAME"].match(VERSION_FORMAT)
+    #
+    # If we're NOT on a gitlab-docs stable branch, fetch the BRANCH_* environment
+    # variable, and if not assigned, set to the default branch.
+    #
+    return ENV.fetch("BRANCH_#{slug.upcase}", default_branch(products[slug].fetch('repo'))) if stable_branch_name.nil?
 
-      case slug
-      # EE has different branch name scheme
-      when 'ee'
-        "#{version[:major]}-#{version[:minor]}-stable-ee"
+    #
+    # Check the project slug to determine the branch name
+    #
+    case slug
 
-      when 'omnibus', 'runner'
-        "#{version[:major]}-#{version[:minor]}-stable"
+    when 'ee'
+      "#{stable_branch_name}-ee"
 
-      # Charts don't use the same version scheme as GitLab, we need to
-      # deduct their version from the GitLab equivalent one.
-      when 'charts'
-        chart = chart_version(ENV.fetch('CI_COMMIT_REF_NAME', nil)).match(VERSION_FORMAT)
-        "#{chart[:major]}-#{chart[:minor]}-stable"
+    when 'omnibus', 'runner'
+      stable_branch_name
 
-      # If the upstream product doesn't follow a stable branch scheme, set the
-      # branch to the default
-      else
-        default_branch(products[slug].fetch('repo'))
-      end
+    # Charts don't use the same version scheme as GitLab, we need to
+    # deduct their version from the GitLab equivalent one.
+    when 'charts'
+      charts_stable_branch
 
-    # If we're NOT on a gitlab-docs stable branch, fetch the BRANCH_* environment
-    # variable, and if not assigned, set to the default branch.
+    # If the upstream product doesn't follow a stable branch scheme, set the
+    # branch to the default
     else
-      ENV.fetch("BRANCH_#{slug.upcase}", default_branch(products[slug].fetch('repo')))
+      default_branch(products[slug].fetch('repo'))
     end
   end
 
@@ -72,6 +66,27 @@ class TaskHelpers
   end
 
   #
+  # If we're on a gitlab-docs stable branch (or targeting one) according to the
+  # regex, catch the version and return the branch name.
+  # For example, 15-8-stable.
+  #
+  # 1. Skip if CI_COMMIT_REF_NAME is not defined (run outside the CI environment).
+  # 2. If CI_COMMIT_REF_NAME matches the version format it means we're on a
+  #    stable branch. Return the version format of that branch.
+  # 3. If CI_MERGE_REQUEST_TARGET_BRANCH_NAME is defined and its value matches
+  #    the version format, return that value.
+  #
+  def stable_branch_name
+    @stable_branch_name ||= begin
+      ref_name = ENV["CI_COMMIT_REF_NAME"]&.match(VERSION_FORMAT)
+      return "#{ref_name[:major]}-#{ref_name[:minor]}-stable" if ref_name
+
+      mr_name = ENV["CI_MERGE_REQUEST_TARGET_BRANCH_NAME"]&.match(VERSION_FORMAT)
+      "#{mr_name[:major]}-#{mr_name[:minor]}-stable" if mr_name
+    end
+  end
+
+  #
   # The charts versions do not follow the same GitLab major number, BUT
   # they do follow a pattern https://docs.gitlab.com/charts/installation/version_mappings.html:
   #
@@ -81,8 +96,8 @@ class TaskHelpers
   # This means we can deduct the charts version from the GitLab version, since
   # the major charts version is always 9 versions behind its GitLab counterpart.
   #
-  def chart_version(gitlab_version)
-    major, minor = gitlab_version.split('.')
+  def charts_stable_branch
+    major, minor = stable_branch_name.split('-')
 
     # Assume major charts version is nine less than major GitLab version.
     # If this breaks and the version isn't found, it might be because they
@@ -90,7 +105,7 @@ class TaskHelpers
     # about it.
     major = major.to_i - 9
 
-    "#{major}.#{minor}"
+    "#{major}-#{minor}-stable"
   end
 
   def default_branch(repo)