Failing to install psycopg2-binary on new docker container

I have encountered a problem while trying to run my django project on a new Docker container. It is my first time using Docker and I can’t seem to find a good way to run a django project on it. Having tried multiple tutorials, I always get the error about psycopg2 not being installed.

requirements.txt:

-i https://pypi.org/simple
asgiref==3.2.7
django-cors-headers==3.3.0
django==3.0.7
djangorestframework==3.11.0
gunicorn==20.0.4
psycopg2-binary==2.8.5
pytz==2020.1
sqlparse==0.3.1

JavaScript
​x
 
-i https://pypi.org/simple
asgiref==3.2.7
django-cors-headers==3.3.0
django==3.0.7
djangorestframework==3.11.0
gunicorn==20.0.4
psycopg2-binary==2.8.5
pytz==2020.1
sqlparse==0.3.1
​

Dockerfile:

# pull official base image
FROM python:3.8.3-alpine

# set work directory
WORKDIR /usr/src/app

# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# install dependencies
RUN pip install --upgrade pip

COPY ./requirements.txt .
RUN pip install -r requirements.txt

# copy project
COPY . .

# set project environment variables
# grab these via Python's os.environ
# these are 100% optional here

ENV PORT=8000
ENV SECRET_KEY_TWITTER = "***"

JavaScript
 
# pull official base image
FROM python:3.8.3-alpine
​
# set work directory
WORKDIR /usr/src/app
​
# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
​
# install dependencies
RUN pip install --upgrade pip
​
COPY ./requirements.txt .
RUN pip install -r requirements.txt
​
# copy project
COPY . .
​
# set project environment variables
# grab these via Python's os.environ
# these are 100% optional here
​
ENV PORT=8000
ENV SECRET_KEY_TWITTER = "***"
​

While running docker-compose build, I get the following error:

Error: pg_config executable not found.

pg_config is required to build psycopg2 from source. Please add the directory

containing pg_config to the $PATH or specify the full executable path with the

option:

python setup.py build_ext --pg-config /path/to/pg_config build ...

or with the pg_config option in 'setup.cfg'.

If you prefer to avoid building psycopg2 from source, please install the PyPI

'psycopg2-binary' package instead.

JavaScript
 
Error: pg_config executable not found.
​
pg_config is required to build psycopg2 from source. Please add the directory
​
containing pg_config to the $PATH or specify the full executable path with the
​
option:
​
python setup.py build_ext --pg-config /path/to/pg_config build ...
​
or with the pg_config option in 'setup.cfg'.
​
If you prefer to avoid building psycopg2 from source, please install the PyPI
​
'psycopg2-binary' package instead.
​

I will gladly answer any questions that might lead to the solution. Also, maybe someone can recommend me a good tutorial on dockerizing django apps?

Answer

On Alpine Linux, you will need to compile all packages, even if a pre-compiled binary wheel is available on PyPI. On standard Linux-based images, you won’t (https://pythonspeed.com/articles/alpine-docker-python/ – there are also other articles I’ve written there that might be helpful, e.g. on security).

So change your base image to python:3.8.3-slim-buster or python:3.8-slim-buster and it should work.

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Answer