This assumes you have already configured the aws command line tool. If not, check out my article on Getting Started with the AWS CLI.

The aws lambda list-layers command can be used to list the Lambda Layers you have created.

aws lambda list-layers

And here is an example of how to limit the output using the --query option.

aws lambda list-layers --query 'Layers[?LayerName==`mylayer`]'

Something like this should be returned.

{
    "Layers": [
        {
            "LayerName": "sam-app7427b055-HelloWorldFunction19d43fc4-DepLayer",
            "LayerArn": "arn:aws:lambda:us-east-1:123456789012:layer:sam-app7427b055-HelloWorldFunction19d43fc4-DepLayer",
            "LatestMatchingVersion": {
                "LayerVersionArn": "arn:aws:lambda:us-east-1:123456789012:layer:sam-app7427b055-HelloWorldFunction19d43fc4-DepLayer:1",
                "Version": 1,
                "Description": "Auto created layer for dependencies of function HelloWorldFunction",
                "CreatedDate": "2023-11-17T02:56:35.074+0000",
                "CompatibleRuntimes": [
                    "python3.9"
                ]
            }
        }
    ]
}

Likewise, the aws lambda list-functions command can be used to list the Lambda Layers connected to a Lambda Function.

~]$ aws lambda list-functions
{
    "Functions": [
        {
            "FunctionName": "sam-app-HelloWorldFunction-MgYCNMibayEZ",
            "FunctionArn": "arn:aws:lambda:us-east-1:123456789012:function:sam-app-HelloWorldFunction-MgYCNMibayEZ",
            "Runtime": "python3.9",
            "Role": "arn:aws:iam::123456789012:role/sam-app-HelloWorldFunctionRole-RiTFI3yH1db7",
            "Handler": "app.lambda_handler",
            "CodeSize": 850,
            "Description": "",
            "Timeout": 3,
            "MemorySize": 128,
            "LastModified": "2023-11-28T02:02:15.000+0000",
            "CodeSha256": "fF2igsgz+Luy1NLV67RoHWDzVT7dnu+ncMbN3tp+Lmg=",
            "Version": "$LATEST",
            "VpcConfig": {
                "SubnetIds": [],
                "SecurityGroupIds": [],
                "VpcId": ""
            },
            "TracingConfig": {
                "Mode": "PassThrough"
            },
            "RevisionId": "a2810ce8-0b8c-4c51-b104-aa8ea677101e",
            "Layers": [
                {
                    "Arn": "arn:aws:lambda:us-east-1:123456789012:layer:sam-app7427b055-HelloWorldFunction19d43fc4-DepLayer:1",
                    "CodeSize": 530296
                },
                {
                    "Arn": "arn:aws:lambda:us-east-1:123456789012:layer:paramiko:1",
                    "CodeSize": 1430666
                }
            ],
            "PackageType": "Zip",
            "Architectures": [
                "x86_64"
            ],
            "EphemeralStorage": {
                "Size": 512
            },
            "SnapStart": {
                "ApplyOn": "None",
                "OptimizationStatus": "Off"
            }
        }
    ]
}