Implement Lambda function versions (#5927)

Author: dsotirho-ucsc

src/azul/terraform.py

@@ -14,6 +14,7 @@
 from pathlib import (
     Path,
 )
+import re
 import subprocess
 from typing import (
     Mapping,
@@ -759,6 +760,10 @@ def tf_config(self, app_name):
         for _, resource in functions:
             assert 'layers' not in resource
             resource['layers'] = ['${aws_lambda_layer_version.dependencies.arn}']
+            # Publishing a new Lambda function version each time lets us update
+            # the Lambda functions atomically, avoiding a race condition between
+            # the update of the function's configuration and its code.
+            resource['publish'] = True
             env = config.es_endpoint_env(
                 es_endpoint=(
                     aws.es_endpoint
@@ -921,6 +926,29 @@ def tf_config(self, app_name):
                 sqs_name, _ = config.unqualified_resource_name(resource_name, suffix)
                 resource['event_source_arn'] = f'${{aws_sqs_queue.{sqs_name}.arn}}'
 
+        # Replace Lambda function ARNs with qualified ARNs for an atomic update.
+        #
+        if app_name == 'indexer':
+            resource_arguments = [
+                ('aws_cloudwatch_event_target', 'arn'),
+                ('aws_lambda_permission', 'function_name'),
+                ('aws_lambda_event_source_mapping', 'function_name'),
+            ]
+        elif app_name == 'service':
+            resource_arguments = [
+                ('aws_cloudwatch_event_target', 'arn'),
+                ('aws_lambda_permission', 'function_name'),
+            ]
+        else:
+            assert False, app_name
+        for resource_type, argument in resource_arguments:
+            for _, resource in json_item_dicts(resources[resource_type]):
+                value = resource[argument]
+                assert value.endswith('.arn}')
+                resource[argument] = value.replace('.arn', '.qualified_arn')
+        locals[app_name] = re.sub(r'(aws_lambda_function\.[^\.\s]+)\.invoke_arn',
+                                  r'\1.qualified_invoke_arn',
+                                  locals[app_name])
         return {
             'resource': resources,
             'data': data,