# How to resolve issues with write-only properties in AWS::Lambda::Function resources
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This topic explains how to resolve issues with write-only properties in [AWS::Lambda::Function](https://docs.amazonaws.cn/AWSCloudFormation/latest/TemplateReference/aws-resource-lambda-function.html) resources when using the IaC generator.

## Issue
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The `AWS::Lambda::Function` resource has three mutually exclusive sets of properties for specifying the Lambda code:
+ `Code/S3Bucket` and `Code/S3Key` properties, and optionally the `Code/S3ObjectVersion` property
+ `Code/ImageUri` property
+ `Code/ZipFile` property

Only one of these sets can be used for a given `AWS::Lambda::Function` resource.

The IaC generator can't determine which set of exclusive write-only properties was used to create or update the resource. As a result, it includes only the first set of properties in the generated template. The `Code/ImageUri` and `Code/ZipFile` properties are omitted. 

Additionally, the IaC generator issues the following warnings:
+ **`MUTUALLY_EXCLUSIVE_PROPERTIES`** – Warns that `Code/S3Bucket` and `Code/S3Key` are identified as mutually exclusive properties.
+ **`UNSUPPORTED_PROPERTIES`** – Warns that the `Code/S3ObjectVersion` property is unsupported.

To include `AWS::Lambda::Function` resources in a generated template, you must download and update the template with the correct code properties.

## Resolution
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**If you store your Lambda code in an Amazon S3 bucket and do not use the `S3ObjectVersion` property**, you can import the generated template without any modifications. The IaC generator will ask you for the Amazon S3 bucket and key as template parameters during the import operation.

****If you store your Lambda code as an Amazon ECR repository**, you can update your template using the following instructions:**

1. Download the generated template.

1. Remove the properties and corresponding parameters for the `Code/S3Bucket` and `Code/S3Key` properties from the generated template.

1. Replace the removed properties in the generated template with the `Code/ImageUri` property, specifying the URL for the Amazon ECR repository.

1. Open the generated template in the IaC generator console and choose the **Import edited template** button.

****If you store your Lambda code as in a zip file**, you can update your template using the following instructions:**

1. Download the generated template.

1. Remove the properties and corresponding parameters for the `Code/S3Bucket` and `Code/S3Key` properties from the generated template.

1. Replace the removed properties in the generated template with the `Code/ZipFile` property.

1. Open the generated template in the IaC generator console and choose the **Import edited template** button.

****If you don’t have a copy of your Lambda code**, you can update your template using the following instructions:**

1. Use the Amazon Lambda [`GetFunction`](https://docs.amazonaws.cn/lambda/latest/api/API_GetFunction.html) API action (for example, by using the [`aws lambda get-function`](https://docs.amazonaws.cn/cli/latest/reference/lambda/get-function.html) Amazon CLI command.

1. In the response, the `RepositoryType` parameter is `S3` if the code is in a Amazon S3 bucket, or `ECR` if the code is in an Amazon ECR repository.

1. In the response, the `Location` parameter contains a pre-signed URL that you can use to download the deployment package for 10 minutes. Download the code.

1. Upload the code to a Amazon S3 bucket.

1. Run an import operation with t he generated template and provide the bucket name and key as parameter values.