[3.x] Pre-import cdk libraries at the beginning of cluster create and update

cli/src/pcluster/models/cluster.py

@@ -66,6 +66,7 @@
 from pcluster.models.s3_bucket import S3Bucket, S3BucketFactory, S3FileFormat, create_s3_presigned_url, parse_bucket_url
 from pcluster.schemas.cluster_schema import ClusterSchema
 from pcluster.templates.cdk_builder import CDKTemplateBuilder
+from pcluster.templates.import_cdk import start as start_cdk_import
 from pcluster.utils import (
     datetime_to_epoch,
     generate_random_name_with_prefix,
@@ -352,6 +353,7 @@ def create(
         raises ClusterActionError: in case of generic error
         raises ConfigValidationError: if configuration is invalid
         """
+        start_cdk_import()
         creation_result = None
         artifact_dir_generated = False
         try:
@@ -887,6 +889,7 @@ def update(
         raises ConfigValidationError: if configuration is invalid
         raises ClusterUpdateError: if update is not allowed
         """
+        start_cdk_import()
         try:
             target_config, changes, ignored_validation_failures = self.validate_update_request(
                 target_source_config, validator_suppressors, validation_failure_level, force

cli/src/pcluster/templates/import_cdk.py

@@ -0,0 +1,27 @@
+import logging
+import time
+from threading import Thread
+
+LOGGER = logging.getLogger(__name__)
+
+
+def import_cdk():
+    """Import cdk libraries."""
+    LOGGER.info("Start importing")
+    begin = time.time()
+    from aws_cdk.core import App  # noqa: F401 pylint: disable=import-outside-toplevel
+
+    from pcluster.templates.cluster_stack import ClusterCdkStack  # noqa: F401 pylint: disable=import-outside-toplevel
+
+    LOGGER.info("Import complete in %i seconds", time.time() - begin)
+
+
+def start():
+    """
+    Import cdk libraries in a separate thread.
+
+    :return: thread importing cdk libraries
+    """
+    thread = Thread(target=import_cdk)
+    thread.start()
+    return thread