aws ecs deploy: --cluster "" (empty string) is not treated as unspecified, unlike omitting --cluster

[Adityaj0]

Describe the bug

ECSClient.get_service_details(), used by aws ecs deploy, has a broken conditional for defaulting the --cluster value:

def get_service_details(self):
    cluster = self._args.cluster

    if cluster is None or '':
        cluster = 'default'

Due to Python operator precedence, this parses as if (cluster is None) or (''):. The empty string literal '' is always falsy, so it contributes nothing to the condition — the or '' is dead code. The check is silently equivalent to just if cluster is None:.

The command's own help text for --cluster says:

If you do not specify a cluster, the "default" cluster is assumed.

That's true when --cluster is omitted entirely (argparse leaves it as None). But if a caller passes --cluster "" — for example a CI/CD pipeline doing aws ecs deploy --cluster "$CLUSTER_NAME" ... where $CLUSTER_NAME is unset or empty — cluster is an empty string, not None, so the fallback to "default" is skipped and the empty string is sent straight through to DescribeServices.

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

--cluster "" should be treated the same as omitting --cluster, and fall back to the "default" cluster, matching the documented behavior.

Current Behavior

describe_services is called with cluster='' instead of cluster='default', which does not match the documented "default cluster is assumed" fallback and will fail cluster/service resolution against the ECS API instead of deploying to the default cluster.

Demonstrated directly against ECSClient.get_service_details():

>>> client._args.cluster = ''
>>> client.get_service_details()
# describe_services is invoked with cluster='' instead of cluster='default'

Reproduction Steps

$ CLUSTER_NAME=
$ aws ecs deploy --service my-service --cluster "$CLUSTER_NAME" \
    --task-definition file://task-def.json \
    --codedeploy-appspec file://appspec.yaml

Because $CLUSTER_NAME is empty, this passes --cluster "", and the command does not fall back to the default cluster the way omitting --cluster entirely would.

Possible Solution

Replace the broken condition with if not cluster:, which correctly treats both None and '' as "not specified" and falls back to 'default' in both cases. I have a PR ready with the fix and regression tests (there was previously no test coverage at all for the cluster-defaulting behavior in get_service_details).

CLI version used

aws-cli/2.36.23 (reproduced on v2 at 4c331fc)

Environment details (OS name and version, etc.)

macOS 15 (Darwin 25.2.0), Python 3.12 — not OS-specific, this is a pure logic bug.

[Adityaj0]

Opened #10557 with the fix and regression tests.