[FIXED] How to solve libpq.so.5 Import error when running postgresql on alpine in docker

Issue

Hi I am trying to run postgresql in alpine in docker with SQLAlchemy and flask but anytime I run my app I get this error ImportError: Error loading shared library libpq.so.5: No such file or directory (needed by /usr/local/lib/python3.8/site-packages/psycopg2/_psycopg.cpython-38-x86_64-linux-gnu.so) I have combed stack overflow for a solution but everyone one them seems to tell me to install psycopg2 which I have done already

 FROM python:3.8.1-alpine3.10 AS build

# ENV PYTHONUNBUFFERED 1

WORKDIR /usr/src/app/restful
COPY requirements.txt /usr/src/app/restful
RUN python -m pip install --upgrade pip
RUN apk update && apk upgrade
RUN apk add libffi-dev
#installing dependencies
# dependencies for libpq postgresql-libs postgresql-dev *remove if not
RUN apk add --no-cache --virtual .build-deps gcc libc-dev py-cryptography libpq postgresql-libs postgresql-dev python3-dev musl-dev make openssl-dev gcc
RUN apk update && apk add --no-cache ca-certificates \
    && update-ca-certificates 2>/dev/null || true
RUN apk add build-base python-dev py-pip jpeg-dev zlib-dev
ENV LIBRARY_PATH=/lib:/usr/lib  
WORKDIR /usr/src/app/restful
COPY requirements.txt  /usr/src/app/restful
COPY supervisord.conf /etc/supervisor/conf.d/supervisord.conf
RUN python -m pip install --upgrade pip
RUN pip install -r requirements.txt
RUN pip install gevent

FROM python:3.8.1-alpine3.10
COPY --from=build /usr/local/lib/python3.8/site-packages/ /usr/local/lib/python3.8/site-packages/
RUN mkdir -p /usr/src/app/restful
RUN set -ex && apk --no-cache add sudo
RUN apk --no-cache --update add libffi libressl
RUN apk update && apk add --no-cache supervisor
RUN pip install psycopg2-binary 

Solution

You seem to be using staged builds in your Dockerfile, and your apk add postgresql-libs is in the first stage. That second FROM stage is building off of a plain python:3.8.1-alpine3.10, not on all the stuff you had done above it, and you're only copying /usr/local/lib/python3.8/site-packages/ over to the second stage. You'll either need to find the full paths of all those dependencies (which could be prohibitively tedious), or just install the dependencies on the second stage as well. Therefore, you need to either build your second stage with FROM build (to include all the other apk deps), or you need to add RUN apk add postgresql-libs gcc libc-dev in the second stage.

So depending on what you're going for, you probably need this:

<...>
RUN pip install -r requirements.txt
RUN pip install gevent

FROM build
RUN mkdir -p /usr/src/app/restful
<...>

or this:

<...>
RUN set -ex && apk --no-cache add sudo
RUN apk --no-cache --update add libffi libressl postgresql-libs gcc libc-dev
RUN apk update && apk add --no-cache supervisor
<...>

Answered By - richyen