Runtime.ExitError AttributeError: 'NoneType' object has no attribute 'next'

[synic]

This is happening to me with the python:3.9-alpine3.12 base image. Here is the Dockerfile:

ARG build_info="head@now"
ARG build_env="development"

FROM python:3.9-alpine3.12 AS base

ARG build_info
ARG build_env

ENV PYTHONPATH=/function
ENV BUILD_INFO=${build_info}

WORKDIR /function
COPY . /function

RUN apk add --no-cache --virtual .build-deps \
    autoconf \
    automake \
    build-base \
    cmake \
    libcurl \
    libexecinfo-dev \
    libstdc++ \
    libtool \
    make \
    postgresql-dev \
    python3-dev \
    && pip install --no-cache-dir -e . \
    && apk del --no-cache .build-deps

FROM base AS build-production
RUN echo " -> Building production image"

FROM base AS build-development
RUN echo " -> Building development image" \
    && apk add --no-cache \
    bash \
    vim \
    iputils \
    && pip3 install --no-cache-dir -e .[debug,testing]

ENV PS1="someapp> "
ENV PYTHONBREAKPOINT=ipdb.set_trace

FROM build-${build_env} AS final

ADD https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie /usr/bin/aws-lambda-rie
COPY entry.sh /
RUN chmod 755 /usr/bin/aws-lambda-rie /entry.sh
ENTRYPOINT [ "/entry.sh" ]
CMD [ "fieldeye.handler" ]

Here's the entry.sh:

#!/bin/sh

if [ -z "${AWS_LAMBDA_RUNTIME_API}" ]; then
    exec /usr/bin/aws-lambda-rie /usr/local/bin/python -m awslambdaric $1
else
    exec /usr/local/bin/python -m awslambdaric $1
fi

and here's the error:

time="2021-02-19T00:09:20.268" level=info msg="exec '/usr/local/bin/python' (cwd=/function, handler=someapp.handler)"
time="2021-02-19T00:09:26.44" level=info msg="extensionsDisabledByLayer(/opt/disable-extensions-jwigqn8j) -> stat /opt/disable-extensions-jwigqn8j: no such file or directory"
START RequestId: 724c1d85-78fc-4424-800e-c745e8bd51a1 Version: $LATEST
time="2021-02-19T00:09:26.441" level=warning msg="Cannot list external agents" error="open /opt/extensions: no such file or directory"
Traceback (most recent call last):
  File "/usr/local/lib/python3.9/runpy.py", line 197, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/local/lib/python3.9/runpy.py", line 87, in _run_code
    exec(code, run_globals)
  File "/usr/local/lib/python3.9/site-packages/awslambdaric/__main__.py", line 21, in <module>
    main(sys.argv)
  File "/usr/local/lib/python3.9/site-packages/awslambdaric/__main__.py", line 17, in main
    bootstrap.run(app_root, handler, lambda_runtime_api_addr)
  File "/usr/local/lib/python3.9/site-packages/awslambdaric/bootstrap.py", line 416, in run
    event_request = lambda_runtime_client.wait_next_invocation()
  File "/usr/local/lib/python3.9/site-packages/awslambdaric/lambda_runtime_client.py", line 76, in wait_next_invocation
    response_body, headers = runtime_client.next()
AttributeError: 'NoneType' object has no attribute 'next'
Executing 'someapp.handler' in function directory '/function'
time="2021-02-19T00:09:26.604" level=warning msg="First fatal error stored in appctx: Runtime.ExitError"
time="2021-02-19T00:09:26.604" level=warning msg="Process 13(python) exited: Runtime exited with error: exit status 1"
time="2021-02-19T00:09:26.604" level=error msg="Init failed" InvokeID= error="Runtime exited with error: exit status 1"
time="2021-02-19T00:09:26.604" level=warning msg="Failed to send default error response: ErrInvalidInvokeID"
time="2021-02-19T00:09:26.604" level=error msg="INIT DONE failed: Runtime.ExitError"
time="2021-02-19T00:09:26.604" level=warning msg="Reset initiated: ReserveFail"

Just to make sure, I ran docker exec -it mycontainer /bin/bash and typed /usr/local/bin/python --version, the response was Python 3.9.1

[synic]

Figured it out, it's because I'm installing libstdc++ as a build library and then uninstalling it after the build completes. It needs to stay installed, so changing the first apk-add bit to this works:

RUN apk add --no-cache \
    libstdc++ \
    libpq \
    && apk add --no-cache --virtual .build-deps \
    autoconf \
    automake \
    build-base \
    cmake \
    libcurl \
    libexecinfo-dev \
    libtool \
    make \
    musl-dev \
    postgresql-dev \
    python3-dev \
    && pip install --no-cache-dir -e . \
    && apk del --no-cache .build-deps

[synic]

By the way, I was able to find out why it wasn't working by looking at the code, specifically this line: https://github.com/aws/aws-lambda-python-runtime-interface-client/blob/main/awslambdaric/lambda_runtime_client.py#L31

try:
    import runtime_client

    runtime_client.initialize_client(_user_agent())
except ImportError:
    runtime_client = None   # THIS LINE HERE

Then, I just opened a python shell and typed import runtime_client

I don't know that it's good that it just silently fails on the import there. Is there a reason to believe the library can work when runtime_client is None?

[jantman]

I've had the same issue, but with python:3.8-alpine. It seems like there are a LOT of assumptions (see also the documentation issue I opened, #24 ) about the container being perfectly set up... when there's little documentation on how to actually do that.

[benoit-laplante]

I had the same issue and had to do the same step as @synic to figure out the cause. In my case, the missing dependency was resolved by installing curl. I would remove except ImportError clause or at least document which dependencies are required by awslambdaric to be installed.

[juls858]

I had the same issue and had to do the same step as @synic to figure out the cause. In my case, the missing dependency was resolved by installing curl. I would remove except ImportError clause or at least document which dependencies are required by awslambdaric to be installed.

This worked for me.

[unacceptable]

For me it was libzstd.so missing (FROM python:3.12-alpine3.19). I just added to my the following to the final stage of my docker multi-stage build.

RUN apk add --no-cache zstd-dev

This was a really annoying issue, and there was no way to identify the cause without additional logging. I have opened a PR and am waiting for guidance about the proper way to log this.

Here's the full Dockerfile if interested:

FROM python:3.12-alpine3.19 as base
ARG FUNCTION_DIR="/app"
WORKDIR ${FUNCTION_DIR}

FROM base as builder
RUN apk update && \
      apk add --no-cache \
        cmake \
        autoconf \
        automake \
        libtool \
        binutils \
        gcc \
        libc-dev \
        make \
        elfutils-dev \
        g++

COPY requirements.txt .
RUN pip install \
      --target ${FUNCTION_DIR} --no-cache-dir -r requirements.txt
COPY app.py .
COPY --chmod=755 entrypoint.sh .
RUN rm requirements.txt

FROM base as final
RUN apk add --no-cache zstd-dev
COPY --from=builder ${FUNCTION_DIR} ${FUNCTION_DIR}
EXPOSE 3000

ENTRYPOINT ["/app/entrypoint.sh"]