[CI] Add dev/codeowners and .go-version file to be synced in backport branches (elastic#13994)

Sync in backport branches dev/codeowners folder, .go-version file 
and update .github/CODEOWNERS file to avoid failures.

Author: mrodm

.buildkite/scripts/backport_branch.sh

@@ -96,10 +96,15 @@ createLocalBackportBranch() {
 
 removeOtherPackages() {
   local sourceFolder=$1
+  local currentPackage=""
   for dir in "$sourceFolder"/*; do
     if [[ -d "$dir" ]] && [[ "$(basename "$dir")" != "$PACKAGE_NAME" ]]; then
       echo "Removing directory: $dir"
       rm -rf "$dir"
+
+      currentPackage=$(basename "${dir}")
+      echo "Removing ${currentPackage} from .github/CODEOWNERS"
+      sed -i "/^\/packages\/${currentPackage}\//d" .github/CODEOWNERS
     fi
   done
 }
@@ -116,70 +121,90 @@ updateBackportBranchContents() {
   local BUILDKITE_FOLDER_PATH=".buildkite"
   local JENKINS_FOLDER_PATH=".ci"
   local files_cached_num=""
+
+  git checkout "$BACKPORT_BRANCH_NAME"
+  echo "Copying $BUILDKITE_FOLDER_PATH from $SOURCE_BRANCH..."
+  git checkout $SOURCE_BRANCH -- $BUILDKITE_FOLDER_PATH
+  git add $BUILDKITE_FOLDER_PATH
+
   if git ls-tree -d --name-only main:.ci >/dev/null 2>&1; then
-    git checkout $BACKPORT_BRANCH_NAME
-    echo "Copying $BUILDKITE_FOLDER_PATH from $SOURCE_BRANCH..."
-    git checkout $SOURCE_BRANCH -- $BUILDKITE_FOLDER_PATH
     echo "Copying $JENKINS_FOLDER_PATH from $SOURCE_BRANCH..."
     git checkout $SOURCE_BRANCH -- $JENKINS_FOLDER_PATH
+    git add $JENKINS_FOLDER_PATH
   else
-    git checkout $BACKPORT_BRANCH_NAME
-    echo "Copying $BUILDKITE_FOLDER_PATH from $SOURCE_BRANCH..."
-    git checkout $SOURCE_BRANCH -- $BUILDKITE_FOLDER_PATH
-    echo "Removing $JENKINS_FOLDER_PATH from $BACKPORT_BRANCH_NAME..."
-    rm -rf "$JENKINS_FOLDER_PATH"
+    if [ -d "${JENKINS_FOLDER_PATH}" ]; then
+      echo "Removing $JENKINS_FOLDER_PATH from $BACKPORT_BRANCH_NAME..."
+      rm -rf "$JENKINS_FOLDER_PATH"
+      git add "$JENKINS_FOLDER_PATH"
+    fi
   fi
 
   # Update scripts used by mage
   local MAGEFILE_SCRIPTS_FOLDER="dev/citools"
   local TESTSREPORTER_SCRIPTS_FOLDER="dev/testsreporter"
   local COVERAGE_SCRIPTS_FOLDER="dev/coverage"
+  local CODEOWNERS_SCRIPTS_FOLDER="dev/codeowners"
+
   if git ls-tree -d --name-only main:${MAGEFILE_SCRIPTS_FOLDER} > /dev/null 2>&1 ; then
     echo "Copying $MAGEFILE_SCRIPTS_FOLDER from $SOURCE_BRANCH..."
     git checkout "$SOURCE_BRANCH" -- "${MAGEFILE_SCRIPTS_FOLDER}"
+    git add ${MAGEFILE_SCRIPTS_FOLDER}
+
     echo "Copying $TESTSREPORTER_SCRIPTS_FOLDER from $SOURCE_BRANCH..."
     git checkout "$SOURCE_BRANCH" -- "${TESTSREPORTER_SCRIPTS_FOLDER}"
+    git add ${TESTSREPORTER_SCRIPTS_FOLDER}
+
     echo "Copying $COVERAGE_SCRIPTS_FOLDER from $SOURCE_BRANCH..."
     git checkout "$SOURCE_BRANCH" -- "${COVERAGE_SCRIPTS_FOLDER}"
+    git add ${COVERAGE_SCRIPTS_FOLDER}
+
+    echo "Copying $CODEOWNERS_SCRIPTS_FOLDER from $SOURCE_BRANCH..."
+    git checkout "$SOURCE_BRANCH" -- "${CODEOWNERS_SCRIPTS_FOLDER}"
+    git add ${CODEOWNERS_SCRIPTS_FOLDER}
+
     echo "Copying magefile.go from $SOURCE_BRANCH..."
     git checkout "$SOURCE_BRANCH" -- "magefile.go"
+    git add magefile.go
+
+    # As this script runs in the context of the main branch (mainly go mod tidy), we need to copy
+    # the .go-version file from the main branch to the backport branch. This avoids failures
+    # installing dependencies in the backport Pull Request.
+    echo "Copying .go-version from $SOURCE_BRANCH..."
+    git checkout "$SOURCE_BRANCH" -- ".go-version"
+    git add .go-version
+
     # Run go mod tidy to update just the dependencies related to magefile and dev scripts
     go mod tidy
+
+    git add go.mod go.sum
   fi
 
   if [ "${REMOVE_OTHER_PACKAGES}" == "true" ]; then
     echo "Removing all packages from $PACKAGES_FOLDER_PATH folder"
     removeOtherPackages "${PACKAGES_FOLDER_PATH}"
-    ls -la $PACKAGES_FOLDER_PATH
+    ls -la "${PACKAGES_FOLDER_PATH}"
+
+    git add "${PACKAGES_FOLDER_PATH}/"
+    git add .github/CODEOWNERS
   fi
 
+  git status
+
   echo "Setting up git environment..."
   update_git_config
 
-  echo "Commiting"
-  git add $BUILDKITE_FOLDER_PATH
-  if [ -d "${JENKINS_FOLDER_PATH}" ]; then
-    git add "${JENKINS_FOLDER_PATH}"
-  fi
-  if [ -d "${MAGEFILE_SCRIPTS_FOLDER}" ] ; then
-    git add ${MAGEFILE_SCRIPTS_FOLDER}
-    git add ${TESTSREPORTER_SCRIPTS_FOLDER}
-    git add go.mod go.sum
-  fi
-  git add $PACKAGES_FOLDER_PATH/
-  git status
-
   files_cached_num=$(git diff --name-only --cached | wc -l)
   if [ "${files_cached_num}" -gt 0 ]; then
+    echo "Committing changes..."
     git commit -m "Add $BUILDKITE_FOLDER_PATH and $JENKINS_FOLDER_PATH to backport branch: $BACKPORT_BRANCH_NAME from the $SOURCE_BRANCH branch"
   else
     echo "Nothing to commit, skip."
   fi
 
   if [ "$DRY_RUN" == "true" ];then
     echo "DRY_RUN mode, nothing will be pushed."
-    # Show just the relevant files diff (go.mod, go.sum, .buildkite, dev and package to be backported)
-    git --no-pager diff $SOURCE_BRANCH...$BACKPORT_BRANCH_NAME go.mod go.sum .buildkite/ dev/ "packages/${PACKAGE_NAME}"
+    # Show just the relevant files diff (go.mod, go.sum, .buildkite, dev, .go-version, .github/CODEOWNERS and package to be backported)
+    git --no-pager diff $SOURCE_BRANCH...$BACKPORT_BRANCH_NAME .buildkite/ dev/ go.sum go.mod .go-version .github/CODEOWNERS "packages/${PACKAGE_NAME}"
   else
     echo "Pushing..."
     git push origin $BACKPORT_BRANCH_NAME