Fix(py/lambda-from-container): Fixes #715 for ecr repo arn

Author: Michael Kaiser

python/lambda-from-container/README.md

@@ -10,7 +10,7 @@ Lambda Function from Container
 
 
 * The **Container Image** is defined in `app.py`.
-  * If `use_pre_existing_image` is **True**, then it is expected that a **Container Image** was **created elsewhere** and will be used by this CDK code.
+  * If `use_pre_existing_image` is **True**, then it is expected that a **Container Image** was **created elsewhere** and will be used by this CDK code and that the image_name is the ECR Repo name.
   * If `use_pre_existing_image` is **False**, then a new container will be created using the `Dockerfile` from the the `lambda-image` sub-directory.
 
 * After deploying the **Lambda Function**, go to the **Lambda Dashboard**, open the **Lambda Function**, and **configure a test event**.

python/lambda-from-container/app.py

@@ -35,7 +35,7 @@ def __init__(self, scope: Construct, id: str, **kwargs) -> None:
             ##
             ecr_repository = aws_ecr.Repository.from_repository_attributes(self,
                 id              = "ECR",
-                repository_arn  ='arn:aws:ecr:{0}:{1}'.format(Aws.REGION, Aws.ACCOUNT_ID),
+                repository_arn  ='arn:aws:ecr:{0}:{1}:repository/{2}'.format(Aws.REGION, Aws.ACCOUNT_ID, image_name),
                 repository_name = image_name
             ) ## aws_ecr.Repository.from_repository_attributes