Trying to use GreengrassCoreIPCClientV2().get_thing_shadow()

Question

The following code looks valid to me. But when I try to run it, inside a greengrass component, I get an incomprehensible error:

...blahblahblah
eventstreamrpc.py", line 723, in _on_continuation_message
    raise shape
awsiot.greengrasscoreipc.model.ServiceError

what? Whats' the error??? :(
I dont see anything relevant in the greengrass.log to explain this either. Just
lifecyclemanager.GenericExternalService: service-errored. {exitCode=1,  ...."

Here's my actual code:

```
import os
from awsiot.greengrasscoreipc.clientv2 import GreengrassCoreIPCClientV2

THINGNAME = os.getenv("AWS_IOT_THING_NAME")
CLIENTOBJ = GreengrassCoreIPCClientV2()

def create_deviceshadow_cache():
    print("DEBUG: thingname is " + THINGNAME)
    shadow_response = CLIENTOBJ.get_thing_shadow(thing_name=THINGNAME)
    print("DEBUG: Printing shadow info: " + shadow_response.payload)

create_deviceshadow_cache()
```

Accepted Answer

Aha. Thanks Michael. After fixing that, .. it still gives me the same error in my component log :-/  But now at least, the main greengrass.log shows me a related error.

```
2023-05-23T15:28:07.053Z [WARN] (Thread-7) com.aws.greengrass.shadowmanager.ipc.GetThingShadowRequestHandler: handle-get-thing-
shadow. Not authorized to get shadow. {thing name=demo-device, shadow name=null}
com.aws.greengrass.authorization.exceptions.AuthorizationException: Principal com.bolthole.copyshadow is not authorized to perf
orm aws.greengrass.ShadowManager:aws.greengrass#GetThingShadow on resource $aws/things/demo-device/shadow
```

Which is odd, because I thought I have allowed all required perms, as shown below.
Any further enlightenment you can give?

In recipe, copied more or less from AWS examples:

```
ComponentConfiguration:
  DefaultConfiguration:
    accessControl:
      aws.greengrass.ShadowManager:
        'com.bolthole.copyshadow:shadow:1':
          policyDescription: 'Allows access to shadows'
          operations:
            - 'aws.greengrass#GetThingShadow'
            - 'aws.greengrass#UpdateThingShadow'
            - 'aws.greengrass#DeleteThingShadow'
          resources:
            - $aws/things/{iot:thingName}/shadow
        'com.bolthole.copyshadow:shadow:2':
          policyDescription: 'Allows access to things with shadows'
          operations:
            - 'aws.greengrass#ListNamedShadowsForThing'
          resources:
            - {iot:thingName}
```

And in my thing policy, I have:

```
    {
      "Effect": "Allow",
      "Action": "iot:GetThingShadow",
      "Resource": "*"
    }
```

(edit: walk through comments for final solution)

Trying to use GreengrassCoreIPCClientV2().get_thing_shadow()

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