Docker build pytest：无法建立新连接：[Errno 111]连接被拒绝

Question

I am facing a serious issue while docker build. The pytest is not working but after build(remove the pytest part) the same pytest work from inside container

Here is my docker file:

    FROM phusion/baseimage:0.9.22

    RUN apt-get update && apt-get install -y build-essential git libaio1 libffi-dev libjpeg-dev libssl-dev libxml2-dev python-wand libmagickwand-dev\
        libxslt-dev libz-dev  python3-pip python3-setuptools unzip


    ADD requirements.pip /
    RUN pip3 install -r /requirements.pip

    VOLUME ["/app"]
    WORKDIR /app
    ADD . .


    EXPOSE 8000
    RUN python3  manage.py runserver 0.0.0.0:8000 &
    RUN python3  -m pytest tests/test_demo.py

Here is my test file:

    import requests

    def test_demo():
        response = requests.get('http://0.0.0.0:8000/' + "demo")
        assert (response.status_code == 200)

Please help.

Answer 1

You can't start a background process in a Dockerfile, or anything that looks like it. In particular, the command

RUN python3 manage.py ... &

exits immediately, and when it does, the intermediate container with the background process is deleted.

I wouldn't try to run this sample code from inside the Dockerfile. I'd end with

CMD ["python3", "manage.py", "runserver", "0.0.0.0:8000"]

Build and launch the image

docker build -t myimage .
docker run -p 8000:8000 myimage

Change the script to take the server location as an environment variable (0.0.0.0 is never a valid IP address to which to connect)

import requests
import os
def test_demo():
   response = requests.get(os.environ['SERVER_URL'] + '/demo')
   assert(response.status_code == 200)

and then run (assuming you're running the client from the same host)

SERVER_URL=http://localhost:8000 pytest

Answer 2

Here is a minimal working example of tests ran with pytest-django in container build stage.

the test script

# test_server.py
import requests


def test_about_page(live_server):
    response = requests.get(live_server.url + '/about')
    response.raise_for_status()

Notice I used the live_server fixture that starts a separate server instance in another thread. I can then access the address via live_server.url in the test.

Similarly, the changes needed to be done in your test would then be:

import requests

def test_demo(live_server):
    response = requests.get(live_server.url + "/demo")
    assert (response.status_code == 200)

the sample Dockerfile

FROM ubuntu:latest

RUN apt update && apt install git python3-pip -y \
    && pip3 install pytest-django django requests
RUN git clone https://github.com/Microsoft/project-python-django-webapp
ADD test_server.py project-python-django-webapp
WORKDIR project-python-django-webapp

RUN pytest -v --ds=python_webapp_django.settings

No magic happens here - I used an example Django project found on Github to run the test for.

building the container

The container build starts the django server and executes the test, completing on test success:

$ docker build -t so/example .
Sending build context to Docker daemon  3.072kB
Step 1/6 : FROM ubuntu:latest
 ---> 113a43faa138
Step 2/6 : RUN apt update && apt install git python3-pip -y && pip3 install pytest-django django requests
 ---> Using cache
 ---> fd7adbe53cc8
Step 3/6 : RUN git clone https://github.com/Microsoft/project-python-django-webapp
 ---> Using cache
 ---> df514c1343c9
Step 4/6 : ADD test_server.py project-python-django-webapp
 ---> 118f74e43370
Step 5/6 : WORKDIR project-python-django-webapp
Removing intermediate container f81db838a81d
 ---> c3d35262f37c
Step 6/6 : RUN pytest -v --ds=python_webapp_django.settings
 ---> Running in e6292f2ac3e8
============================= test session starts ==============================
platform linux -- Python 3.6.5, pytest-3.6.3, py-1.5.4, pluggy-0.6.0 -- /usr/bin/python3
cachedir: .pytest_cache
Django settings: python_webapp_django.settings (from command line option)
rootdir: /project-python-django-webapp, inifile:
plugins: django-3.3.2
collecting ... collected 1 item

test_server.py::test_index PASSED                                        [100%]

=========================== 1 passed in 1.13 seconds ===========================
Removing intermediate container e6292f2ac3e8
 ---> c78c589b6d74
Successfully built c78c589b6d74
Successfully tagged so/example:latest