Support for docker compose > v2

**PySDK Version**
- [ ] PySDK V2 (2.x)
- [X] PySDK V3 (3.x)

**Describe the bug**
Unable to run sagemaker training in "local" mode with docker version v5.

**Component**: ``sagemaker.train.local.local_container._LocalContainer._get_compose_cmd_prefix``

[_get_compose_cmd_prefix()](https://github.com/aws/sagemaker-python-sdk/blob/91ca011daa8853ee031e784c35a5bab23a79ad08/sagemaker-core/src/sagemaker/core/local/image.py#L153-L168) only recognizes Docker Compose **v2** by
checking ``"v2" in output``. Docker Compose **v5.x** (and v3, v4, or any
future major version) is silently rejected, causing::

ImportError: Docker Compose is not installed.
Local Mode features will not work without docker compose.

even though ``docker compose`` is fully installed and functional.

The substring check ``"v2" in output`` is too narrow. Every Compose
version with a major number other than 2 is treated as "not installed".

**To reproduce**
A clear, step-by-step set of instructions to reproduce the bug.

Required for Test:
docker pull docker:latest
docker tag image to docker:latest

# Make sure the latest version is > 2
docker run --rm docker:latest docker compose version
# Docker Compose version v5.1.1

The provided code need to be **complete** and **runnable**, if additional data is needed, please include them in the issue.

```
import re
import subprocess

import mock

def test_local_train_triggers_compose_v5_bug(tmp_path):
"""Invoke sagemaker local-mode training to prove Docker Compose v5 triggers the bug.

This test exercises the real call chain:
ModelTrainer.train()
→ _LocalContainer.train()
→ _LocalContainer._generate_compose_command()
→ _LocalContainer._get_compose_cmd_prefix() ← bug lives here

The bug: ``_get_compose_cmd_prefix`` only accepts output containing "v2".
Any Compose v3/v4/v5 output causes an ``ImportError`` even though Docker
Compose is fully installed and functional.

Assumes ``docker:latest`` is already pulled on the local workstation.
"""
import os
import boto3
from moto import mock_aws
from sagemaker.core.local import LocalSession
from sagemaker.core.training.configs import Compute, InputData, OutputDataConfig, SourceCode
from sagemaker.train.model_trainer import ModelTrainer, Mode

#Assumes a local docker:latest image is already pulled, which contains a real compose version string in its output. If this test starts failing due to a compose version update, update this image to one that contains a compose version string that triggers the bug (v3+).
PUBLIC_DOCKER_IMAGE = "docker:latest"

# Step 1: get the real compose version string from the local docker:latest image
result = subprocess.run( # nosec B603 B607
["docker", "run", "--rm", PUBLIC_DOCKER_IMAGE, "docker", "compose", "version"],
capture_output=True,
text=True,
timeout=30, # image assumed already pulled — no pull delay
)
assert result.returncode == 0, (
f"Could not get compose version from {PUBLIC_DOCKER_IMAGE}:\n{result.stderr}"
)
real_version_output = result.stdout # e.g. "Docker Compose version v5.1.1\n"

match = re.search(r"v(\d+)", real_version_output.strip())
assert match is not None, f"Could not parse version from: {real_version_output!r}"
major_version = int(match.group(1))

if major_version == 2:
print(
f"docker:latest ships Compose v{major_version} — bug only triggers on v3+. "
"Update PUBLIC_DOCKER_IMAGE to an image that ships Compose v3+."
)

# Step 2: build a minimal LocalSession backed by moto
with mock_aws():
boto_session = boto3.Session(region_name="us-east-1")
s3 = boto_session.client("s3")
s3.create_bucket(Bucket="sagemaker-bug-repro")

sm_session = LocalSession(
boto_session=boto_session,
default_bucket="sagemaker-bug-repro",
sagemaker_config={
"SchemaVersion": "1.0",
"SageMaker": {"PythonSDK": {"Modules": {"TelemetryOptOut": True}}},
},
)
sm_session.config = {
"local": {"local_code": True, "container_root": str(tmp_path)}
}
sm_session._default_bucket = "sagemaker-bug-repro"

# Step 3: build a ModelTrainer pointing at the public docker:latest image.
# We mock subprocess.check_output so the SDK receives the *real* version
# string from the public image instead of whatever is installed on this host.
trainer = ModelTrainer(
training_image=PUBLIC_DOCKER_IMAGE,
role="arn:aws:iam::123456789012:role/fake-role",
compute=Compute(instance_type="local_cpu", instance_count=1),
sagemaker_session=sm_session,
output_data_config=OutputDataConfig(s3_output_path="s3://sagemaker-bug-repro/output"),
base_job_name="compose-v5-bug",
training_mode=Mode.LOCAL_CONTAINER,
local_container_root=str(tmp_path),
source_code=SourceCode(command="true"), # no-op command
)

# Step 4: patch subprocess so _get_compose_cmd_prefix sees the real
# version string from docker:latest (v5.x), then assert the bug fires.
with (
mock.patch("subprocess.check_output", return_value=real_version_output),
mock.patch("shutil.which", return_value=None),
):
trainer.train(wait=False, logs=False)

```

**Expected behavior**
sagemaker train in local mode should not error

**Screenshots or logs --- STACK Trace**
```
.tox/py313/lib/python3.13/site-packages/sagemaker/core/telemetry/telemetry_logging.py:187: in wrapper
raise caught_ex
.tox/py313/lib/python3.13/site-packages/sagemaker/core/telemetry/telemetry_logging.py:153: in wrapper
response = func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
.tox/py313/lib/python3.13/site-packages/sagemaker/core/workflow/pipeline_context.py:346: in wrapper
return run_func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
.tox/py313/lib/python3.13/site-packages/pydantic/_internal/_validate_call.py:39: in wrapper_function
return wrapper(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^
.tox/py313/lib/python3.13/site-packages/pydantic/_internal/_validate_call.py:136: in __call__
res = self.__pydantic_validator__.validate_python(pydantic_core.ArgsKwargs(args, kwargs))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.tox/py313/lib/python3.13/site-packages/sagemaker/train/model_trainer.py:813: in train
local_container.train(wait)
.tox/py313/lib/python3.13/site-packages/sagemaker/train/local/local_container.py:237: in train
compose_command = self._generate_compose_command(wait)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.tox/py313/lib/python3.13/site-packages/sagemaker/train/local/local_container.py:479: in _generate_compose_command
_compose_cmd_prefix = self._get_compose_cmd_prefix()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = _LocalContainer(training_job_name='a-test-20260408132342', instance_type='local_cpu', instance_count=1, image='glm-sta...er_arguments=['-c', 'chmod +x /opt/ml/input/data/sm_drivers/sm_train.sh && /opt/ml/input/data/sm_drivers/sm_train.sh'])
def _get_compose_cmd_prefix(self) -> List[str]:
"""Gets the Docker Compose command.

The method initially looks for 'docker compose' v2
executable, if not found looks for 'docker-compose' executable.

Returns:
List[str]: Docker Compose executable split into list.

Raises:
ImportError: If Docker Compose executable was not found.
"""
compose_cmd_prefix = []

output = None
try:
output = subprocess.check_output(
["docker", "compose", "version"],
stderr=subprocess.DEVNULL,
encoding="UTF-8",
)
except subprocess.CalledProcessError:
logger.info(
"'Docker Compose' is not installed. "
"Proceeding to check for 'docker-compose' CLI."
)

if output and "v2" in output.strip():
logger.info("'Docker Compose' found using Docker CLI.")
compose_cmd_prefix.extend(["docker", "compose"])
return compose_cmd_prefix

if shutil.which("docker-compose") is not None:
logger.info("'Docker Compose' found using Docker Compose CLI.")
compose_cmd_prefix.extend(["docker-compose"])
return compose_cmd_prefix

> raise ImportError(
"Docker Compose is not installed. "
"Local Mode features will not work without docker compose. "
"For more information on how to install 'docker compose', please, see "
"https://docs.docker.com/compose/install/"
)
E ImportError: Docker Compose is not installed. Local Mode features will not work without docker compose. For more information on how to install 'docker compose', please, see https://docs.docker.com/compose/install/
.tox/py313/lib/python3.13/site-packages/sagemaker/train/local/local_container.py:638: ImportError
```

```
# ═══════════════════════════════════════════════════════════════════════════
# PROPOSED FIX – standalone validation of the corrected logic
# ═══════════════════════════════════════════════════════════════════════════

def _fixed_compose_check(output: str | None) -> bool:
"""Proposed replacement for the ``"v2" in output`` check.

Accepts any Docker Compose plugin version >= 2.0.0.

Examples
--------
>>> _fixed_compose_check("Docker Compose version v5.1.1")
True
>>> _fixed_compose_check("Docker Compose version v2.27.0")
True
>>> _fixed_compose_check("Docker Compose version v1.29.2")
False
>>> _fixed_compose_check("")
False
>>> _fixed_compose_check(None)
False
"""
if not output:
return False
match = re.search(r"v(\d+)", output.strip())
return match is not None and int(match.group(1)) >= 2
```

**System information**
A description of your system. Please provide:
- **SageMaker Python SDK version**: sagemaker-train (>=1.6.0,<2.0.0) / sagemaker-core (>=2.7.1,<3.0.0)
- **Framework name (eg. PyTorch) or algorithm (eg. KMeans)**: NA
- **Framework version**: sagemaker-train (>=1.6.0,<2.0.0) / sagemaker-core (>=2.7.1,<3.0.0)
- **Python version**: 3.13
- **CPU or GPU**: CPU
- **Custom Docker image (Y/N)**: N

**Additional context**
Add any other context about the problem here.

Start at sagemaker/train/local/local_container.py and inspect _get_compose_cmd_prefix(), which currently checks the Docker Compose version output. Add focused coverage for supported Compose major versions and the fallback CLI, then run the local training tests; done means Docker Compose v2 and later work without an ImportError while unsupported or unavailable commands still follow the fallback path.

Written by the indexing model from the issue text.