Inconsistent error codes when resources do not exist

[boompig]

Sample code:

from aws_utils import make_session

from botocore.exceptions import ClientError
session = make_session()

cf = session.resource("cloudformation")
s3 = session.resource("s3")
iam = session.resource("iam")
ec2 = session.resource("ec2")

bucket = s3.Bucket("foo")
instance = ec2.Instance("i-00135460c82faa880")
role = iam.Role("foo")
stack = cf.Stack("foo")

for resource in [bucket, instance, role, stack]:
    print(type(resource))
    try:
        resource.load()
    except ClientError as e:
        print(e.response["Error"])

Output:

<class 'boto3.resources.factory.s3.Bucket'>
{'Message': 'NotFound', 'Code': '404'}
<class 'boto3.resources.factory.ec2.Instance'>
{'Message': "The instance ID 'i-00135460c82faa880' does not exist", 'Code': 'InvalidInstanceID.NotFound'}
<class 'boto3.resources.factory.iam.Role'>
{'Message': 'Role not found for foo', 'Code': 'NoSuchEntity', 'Type': 'Sender'}
<class 'boto3.resources.factory.cloudformation.Stack'>
{'Message': 'Stack with id foo does not exist', 'Code': 'ValidationError', 'Type': 'Sender'}

There should be some consistency in these cases, since they're basically the same operation and failure. NoSuchEntity seems like the reasonable return code.

[boompig]

And for a few services that don't have the Resource semantics and only support clients:

def test_clients():
    l_cli = session.client("lambda")
    try:
        l_cli.get_function(FunctionName="foo")
    except ClientError as e:
        print(e.response["Error"])
    k_cli = session.client("kinesis")
    try:
        # closest I could find to `get_stream`, which doesn't exist
        k_cli.describe_stream(StreamName="foo")
    except ClientError as e:
        print(e.response["Error"])

test_clients()

Output:

{'Message': u'Function not found: arn:aws:lambda:us-west-1:xxxxxxxxxxx:function:foo', 'Code': 'ResourceNotFoundException'}
{'Message': u'Stream foo under account xxxxxxxxxxx not found.', 'Code': u'ResourceNotFoundException'}

This is PHP-level inconsistency.

[JordonPhillips]

Unfortunately there's nothing we can do about that since it's a service-side issue, and changing it now would be backwards-incompatible besides. FWIW I agree that it's confusing.