Max length char of 140 for layers arn in lambda update-function-configuration --layers command

[gcontarini]

Describe the bug

Cannot update the many layers from a lambda function using cli if more than one layer is used.
Also, cannot update layers incrementally since the command replaces all layers at once, so if the layer ARN is not provided it will be removed from the lambda.

Expected Behavior

Expected to all layers provided in the sequence to be added/updated to the function.

Current Behavior

The following error is shown:

An error occurred (ValidationException) when calling the UpdateFunctionConfiguration operation: 1 validation error detected: Value 'FULL_LAYER_ARN_1,FULL_LAYER_ARN_2' at 'layers' failed to satisfy constraint: Member must satisfy constraint: [Member must have length less than or equal to 140, Member must have length greater than or equal to 1, Member must satisfy regular expression pattern: (arn:[a-zA-Z0-9-]+:lambda:[a-zA-Z0-9-]+:\d{12}:layer:[a-zA-Z0-9-_]+:[0-9]+)|(arn:[a-zA-Z0-9-]+:lambda:::awslayer:[a-zA-Z0-9-_]+), Member must not be null]

Reproduction Steps

While trying to update the layers from a given lambda function with the following command:

aws lambda update-function-configuration --function-name FUNCTION_NAME --layers FULL_LAYER_ARN_1,FULL_LAYER_ARN_2

Use 2 or more layers in the same call and the error will show.

Possible Solution

Allow to use more than 140 chars in the layers parameter if the parameter is a comma separated value, meaning there are multiple layer ARNs being provided.

Additional Information/Context

No response

CLI version used

aws-cli/2.13.26

Environment details (OS name and version, etc.)

Python/3.11.6 Darwin/23.0.0 source/arm64

[tim-finnigan]

Hi @gcontarini - thanks for your patience here. The CLI update-function-config command corresponds to the Lambda UpdateFunctionConfig API. Therefore, any changes to the ARN validation requirements would need to be implemented by the Lambda service team (and then would be reflected in the AWS CLI/SDKs).

But in this case it appears that the input validation will fail with a comma-separated list even if each individual ARN or total length of ARNs is less than 140 chars. As an alternative, you can use the --cli-input-json parameter, for example:

aws lambda update-function-configuration \
    --function-name <function_name> \
    --cli-input-json '{"Layers": ["arn:aws:lambda:us-west-2:<account>:layer:<layer>:<version>", "arn:aws:lambda:us-west-2:<account>:layer:<layer>:<version>, "arn:aws:lambda:us-west-2:<account>:layer:<layer>:<version>"]}'

Maybe the CLI documentation could be improved here in regard to when --cli-input-json should be used versus a comma-separated list.

Edit: updating this to a feature request to improve the documentation here, specifically to have more visibility on when to use --cli-input-json. But as mentioned, the 140 length limit is imposed by the API: