pymongo_inmemory doesn't work in docker container alpine

[trolliama]

Describe the bug
I am having troubles in running my tests inside my docker alpine container. I installed the pymongo_inmemory properly and started the tests and this was returned to me:

FileNotFoundError: [Errno 2] No such file or directory: '/usr/src/venv/lib/python3.9/site-packages/pymongo_inmemory/downloader/../.cache/extract/mongodb-linux-x86_64-4.0.23-tgz/mongodb-linux-x86_64-4.0.23/bin/mongod'

I verified it and the mongod binary is there. So i tried to run the subprocess.Popen to just ls the folders and indeed the error appeared.
With a little bit of research I've found that using the shell=True option in the Popen() class like this: subprocess.Popen(["ls path/to/bin"], shell=True) worked, but when I tried to run the mongod with this command it gave me this error:

/bin/sh: /usr/src/venv/lib/python3.9/site-packages/pymongo_inmemory/downloader/../.cache/extract/mongodb-linux-x86_64-4.0.23-tgz/mongodb-linux-x86_64-4.0.23/bin/mongod: not found

Obs: In my machine works if I don't use the docker container

To Reproduce
Steps to reproduce the behavior:

1. Create tests (I used pytest)
2. Create a dockerfile (I used the alpine):

FROM python:3.9-alpine AS builder

RUN pip install --user pipenv

WORKDIR /usr/src

RUN apk update
RUN apk add postgresql-dev gcc python3-dev musl-dev
RUN apk add postgresql

ADD Pipfile.lock Pipfile /usr/src/

RUN /root/.local/bin/pipenv lock --dev -r > requirements.txt

RUN python -m venv venv
RUN venv/bin/pip install -r requirements.txt

FROM python:3.9-alpine AS runtime

RUN mkdir -v /usr/src/venv
COPY --from=builder /usr/src/venv /usr/src/venv

RUN apk update
RUN apk add gcc postgresql

WORKDIR /usr/src

RUN ln -snf /usr/share/zoneinfo/America/Sao_Paulo \
    /etc/localtime && \
    echo "America/Sao_Paulo" > /etc/timezone

COPY ./src/app ./app
COPY ./src/tests ./tests
COPY ./src/main.py ./

# Copy the crontab configuration file
COPY ./cronjobs/execute_updater.dev ./cronjobs/execute_updater
RUN /usr/bin/crontab ./cronjobs/execute_updater
RUN touch /var/log/cron.log

# path the python venv bin - tru not to change since its needed in the ci pipeline
# CMD  /usr/sbin/crond -f -l 8 & tail -f /var/log/cron.log
CMD ["python", "-m", "http.server", "8080"]

3. Run the container and then run the tests (I ran inside the container itself)
4. The error appears

Expected behavior
It's expected that the tests pass

Screenshots

Context:

• Version of pymongo_inmemory [~=0.2.5]
• python3.9-alpine docker image

[trolliama]

I tried to use the ubuntu:20.04 image and it worked as expected, but would be great if was possible to use the alpine since its lightweight

[ekarademir]

Hi @trolliama,

How do you set up the version in your docker image? The library itself doesn't do any compilation. It basically downloads a suitable version. See https://github.com/kaizendorks/pymongo_inmemory#available-mongodb-versions

It looks like Apline linux is not supported by MongoDB itself. Probably then it's falling back to generic version. That being said, FileNotFound error looks fishy. I'll publisha fix recently merged to master. Maybe that would fix this problem too.

[ekarademir]

Maybe related to #52 and maybe closed by #53

[sebastus]

Our test engine is configured by default to run tests in parallel. As I understand it, pymongo_inmemory downloads mongo on first access. If a test running in parallel with that first request attempts to access the database, it's no longer the first access, so rather than trying to download mongo, it attempts to run the query. But mongo isn't installed yet.

Is there a way to pre-load mongo so that on first access, the query can just go ahead and run?

[ekarademir]

Hey @sebastus this is a very interesting use case. To summarise what I understood

• Test 1 (first past the post) creates a MongoClient (using pymongo_in_memory, which downloads it and starts extracting
• Test 2 sees that there is already a downloaded version so it assumes that there is an accessible binary so it goes down to running it and fails.

I am in the middle of refactoring how this download and running business works. I will try to incorporate that as well. But in the mean time I think there is a workaround.

With #65 you should be able to point to a "local" mongod instance. So you can pre-download the binary and point to it for the tests.

That being said, I think there is still not a good way to provide that path. So that's something I should add to that refactor.