Does AWS PowerTools support Lambda using container image?

[gnought]

Without AWS PowerTools, a minimal Lambda function using a container image looks like below. This work flawlessly.

app.py

import logging

logger = logging.getLogger()
logger.setLevel("DEBUG")

def handler(event, context):
    logger.debug("hello")
    return`

However switching to AWS PowerTools as below, I come up an error. It looks like AWS PowerTools is incompatible with awslambdaric.

app.py

from aws_lambda_powertools import Logger

logger = Logger()

def handler(event, context):
    logger.debug("hello")
    return

07 Dec 2025 07:45:50,538 [INFO] (rapid) exec '/var/runtime/bootstrap' (cwd=/var/task, handler=)
START RequestId: 632c768b-e4ef-4ba5-935e-d96e4721eebd Version: $LATEST
07 Dec 2025 07:45:51,978 [INFO] (rapid) INIT START(type: on-demand, phase: init)
07 Dec 2025 07:45:51,979 [INFO] (rapid) Starting runtime without AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN , Expected?: false
[WARNING]       2025-12-07T07:45:52.021Z                LAMBDA_WARNING: Unhandled exception. The most likely cause is an issue in the function code. However, in rare cases, a Lambda runtime update can cause unexpected function behavior. For functions using managed runtimes, runtime updates can be triggered by a function change, or can be applied automatically. To determine if the runtime has been updated, check the runtime version in the INIT_START log entry. If this error correlates with a change in the runtime version, you may be able to mitigate this error by temporarily rolling back to the previous runtime version. For more information, see https://docs.aws.amazon.com/lambda/latest/dg/runtimes-update.html
    warnings.warn("POWERTOOLS_DEBUG environment variable is enabled. Setting logging level to DEBUG.", stacklevel=2)
Exception ignored in: <socket.socket fd=3, family=2, type=1, proto=6, laddr=('127.0.0.1', 55310), raddr=('127.0.0.1', 9001)>
Traceback (most recent call last):
  File "/var/lang/lib/python3.13/site-packages/awslambdaric/lambda_runtime_client.py", line 108, in post_init_error
    self.call_rapid(
ResourceWarning: unclosed <socket.socket fd=3, family=2, type=1, proto=6, laddr=('127.0.0.1', 55310), raddr=('127.0.0.1', 9001)>
07 Dec 2025 07:45:52,039 [WARNING] (rapid) First fatal error stored in appctx: Runtime.ExitError
07 Dec 2025 07:45:52,039 [WARNING] (rapid) Process runtime-1 exited: exit status 1
07 Dec 2025 07:45:52,039 [INFO] (rapid) INIT RTDONE(status: error)
07 Dec 2025 07:45:52,039 [INFO] (rapid) INIT REPORT(durationMs: 60.936000)
07 Dec 2025 07:45:52,039 [ERROR] (rapid) Init failed error=Runtime exited with error: exit status 1 InvokeID=
07 Dec 2025 07:45:52,039 [WARNING] (rapid) Shutdown initiated: spindown
07 Dec 2025 07:45:52,039 [INFO] (rapid) Waiting for runtime domain processes termination
07 Dec 2025 07:45:52,040 [INFO] (rapid) INIT START(type: on-demand, phase: invoke)
07 Dec 2025 07:45:52,040 [INFO] (rapid) INIT REPORT(durationMs: 0.063000)
07 Dec 2025 07:45:52,040 [INFO] (rapid) INVOKE START(requestId: 3301816c-a1b5-43b8-8cf3-7a9c7bad0344)
07 Dec 2025 07:45:52,040 [ERROR] (rapid) Invoke failed error=Runtime exited with error: exit status 1 InvokeID=3301816c-a1b5-43b8-8cf3-7a9c7bad0344
07 Dec 2025 07:45:52,040 [ERROR] (rapid) Invoke DONE failed: Sandbox.Failure
07 Dec 2025 07:45:52,040 [WARNING] (rapid) Reset initiated: ReleaseFail
07 Dec 2025 07:45:52,040 [INFO] (rapid) Waiting for runtime domain processes termination

The docker build and run are as below:

docker build -t test -F Dockerfile .
docker run --rm -p 9000:8080 \
		-e POWERTOOLS_DEBUG=true \
		-e POWERTOOLS_LOG_LEVEL=DEBUG \
		-v $(PWD)/app.py:/var/task/app.py \
		test

Dockerfile

# syntax=docker/dockerfile:1

ARG PYTHON_VERSION=3.13

FROM public.ecr.aws/lambda/python:${PYTHON_VERSION} AS lambda
ENV PYTHONUNBUFFERED=1 \
    PYTHONWARNINGS=error \
    POWERTOOLS_DEBUG=true

RUN <<EOF
  mkdir -p /opt/{extensions,python}
  pip install --no-cache-dir --target /opt/python aws-lambda-powertools
EOF

COPY --link --chmod=0644 app.py ${LAMBDA_TASK_ROOT}/app.py

CMD [ "app.handler" ]

[gnought]

It looks I found the root clause.

aws_lambda_powertools/init.py -> call set_package_logger_handler() -> call powertools_debug_is_set()
As POWERTOOLS_DEBUG=true, powertools_debug_is_set() triggers warnings.warn() which throws an Exception

The Exception is caught in awslambdaric bootstrap.py and results sys.exit(1)
https://github.com/aws/aws-lambda-python-runtime-interface-client/blob/3f43f4d089600669435038d7e1fa41145d9ff94f/awslambdaric/bootstrap.py#L506-L516

In addition, an environment PYTHONWARNINGS=error is set in AWS public.ecr.aws/lambda/python:3.13 image

To work with container as a Lambda runtime, a workaround is to capture all warnings while importing AWS PowerTools.

import logging
import warnings

with warnings.catch_warnings(record=True) as captured_warnings:
    warnings.filterwarnings("always", category=UserWarning)
    from aws_lambda_powertools import Logger

    for warning_message in captured_warnings:
        logging.warning(warning_message)

logger = Logger()
# logger = logging.getLogger()
# logger.setLevel("DEBUG")


def handler(event, context):
    logger.debug("hello")
    return

This will result a normal behavior with the logged UserWarnings without exit the Lambda. This might not be ideal in production but it is useful for local debugging.

10 Dec 2025 14:50:58,204 [INFO] (rapid) exec '/var/runtime/bootstrap' (cwd=/var/task, handler=)
START RequestId: e36d708a-93fe-4ae7-8759-0990f7064d64 Version: $LATEST
10 Dec 2025 14:50:59,783 [INFO] (rapid) INIT START(type: on-demand, phase: init)
10 Dec 2025 14:50:59,783 [INFO] (rapid) Starting runtime without AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, AWS_SESSION_TOKEN , Expected?: false
[WARNING]       2025-12-10T14:50:59.868Z                {message : UserWarning('POWERTOOLS_DEBUG environment variable is enabled. Setting logging level to DEBUG.'), category : 'UserWarning', filename : '/opt/python/aws_lambda_powertools/package_logger.py', lineno : 20, line : None}
2025-12-10 14:50:59,868 aws_lambda_powertools.logging.logger [DEBUG] Adding filter in root logger to suppress child logger records to bubble up
[DEBUG] 2025-12-10T14:50:59.868Z                Adding filter in root logger to suppress child logger records to bubble up
2025-12-10 14:50:59,868 aws_lambda_powertools.logging.logger [DEBUG] Marking logger service_undefined as preconfigured
[DEBUG] 2025-12-10T14:50:59.868Z                Marking logger service_undefined as preconfigured
10 Dec 2025 14:50:59,869 [INFO] (rapid) INIT RTDONE(status: success)
10 Dec 2025 14:50:59,869 [INFO] (rapid) INIT REPORT(durationMs: 86.483000)
10 Dec 2025 14:50:59,869 [INFO] (rapid) INVOKE START(requestId: 0729ba63-16b9-4084-913c-8ff3d23587d3)
{"level":"DEBUG","location":"handler:17","message":"hello","timestamp":"2025-12-10 14:50:59,870+0000","service":"service_undefined"}
10 Dec 2025 14:50:59,871 [INFO] (rapid) INVOKE RTDONE(status: success, produced bytes: 0, duration: 1.676000ms)
END RequestId: 0729ba63-16b9-4084-913c-8ff3d23587d3
REPORT RequestId: 0729ba63-16b9-4084-913c-8ff3d23587d3  Init Duration: 0.12 ms  Duration: 88.71 ms      Billed Duration: 89 ms  Memory Size: 3008 MB    Max Memory Used: 3008 MB
^C10 Dec 2025 14:57:55,773 [INFO] (rapid) Received signal signal=interrupt
10 Dec 2025 14:57:55,773 [INFO] (rapid) Shutting down...
10 Dec 2025 14:57:55,774 [WARNING] (rapid) Reset initiated: SandboxTerminated
10 Dec 2025 14:57:55,774 [INFO] (rapid) Sending SIGKILL to runtime-1(17).
10 Dec 2025 14:57:55,778 [INFO] (rapid) Waiting for runtime domain processes termination