Working from_resolve jinja2 function. Does not support cross account (#21)

Author: JohnPreston

docs/jinja2_functions_filters.rst

@@ -37,6 +37,26 @@ Parameters:
 * ``fallback_value``: a value to use if case the property is missing.
 
 
+from_resolve
+--------------
+
+Parameter: A string that looks like the {{resolve:}} string in AWS CloudFormation
+
+For example, building the string below, we retrieve the key `SASL_JAAS_CONFIG` from the content of the secret, which we
+get the ARN from the `env_var` function with value `SECRET_ARN`
+
+.. code-block:: yaml
+
+    files:
+      /tmp/secret.test:
+        content: |
+          client.id=sainsburys.applications.sc-ce.cdk-gateway
+          sasl.mechanism=PLAIN
+          sasl.jaas.config={{ from_resolve('{{resolve:secretsmanager:'  + env_var('SECRET_ARN') + ':SecretString:SASL_JAAS_CONFIG}}') | safe }}
+          security.protocol=SASL_SSL
+          #EOF
+
+
 
 AWS Specific Filters
 =====================

ecs_files_composer/jinja2_filters/__init__.py

@@ -11,6 +11,7 @@
 
 import requests
 import yaml
+from aws_cfn_custom_resource_resolve_parser import handle
 from boto3.session import Session
 from flatdict import FlatDict, FlatterDict
 
@@ -210,12 +211,17 @@ def hostname(alternative_value: str = None) -> str:
         return alternative_value
 
 
+def using_resolve(resolve_string: str) -> str:
+    return handle(resolve_string)
+
+
 JINJA_FUNCTIONS = {
     "ecs_container_metadata": ecs_container_metadata,
     "ecs_task_metadata": ecs_task_metadata,
     "env_var": env_var,
     "from_ssm": from_ssm,
     "from_ssm_json": from_ssm_json,
+    "from_resolve": using_resolve,
     "msk_bootstrap": msk_bootstrap,
     "hostname": hostname,
 }