How to connect postgis to django in docker

NOTE: There is an official image for postgis now https://hub.docker.com/r/postgis/postgis. Use that instead. Also in example below I am using alpine which is not recommended as python base due to issues with wheels (read more https://pythonspeed.com/articles/alpine-docker-python/)

Problem here that you are not using correct postgis image

version: '3'services:  web:    build: .    command: python3 manage.py runserver 0.0.0.0:8000    volumes:      - .:/code    ports:      - "8000:8000"    depends_on:      - db  db:    image: mdillon/postgis:10 # <- here    environment:      - POSTGRES_HOST=db  # default postgres      - POSTGRES_PASSWORD=password  # default postgres      # all env vars bellow are redundant because they are same as default values      # - POSTGRES_PORT=5432      # - POSTGRES_NAME=postgres      # - POSTGRES_USER=postgres

Here is my alpine based config for working with postgis

NOTE: all my django code is stored in ./backend folder and I use Pipenv, alsothis project is using https://github.com/joke2k/django-environ to set DATABASES via DATABASE_URL in my settings

DATABASES = {    'default': env.db(default='postgis://postgres:postgres@postgres:5432/postgres')}

docker-compose.yml

version: "3.7"services:    postgres:        image: mdillon/postgis:10-alpine        volumes:            - ./docker/postgres/:/docker-entrypoint-initdb.d/            - postgres_data:/var/lib/postgresql/data    backend:        build:            context: .            dockerfile: docker/backend/Dockerfile        ports:            - "8000:8000"        depends_on:            - postgres        volumes:            - ./backend:/project/backendvolumes:    postgres_data:

docker/backend/Dockerfile

FROM python:3.6-alpine3.8# postgresql-client is required by psql# postgresql-dev musl-dev gcc are required by psycopg# NOTE: there is py3-psycopg2# libxml2-dev libxslt-dev are required by lxml# gdal-dev geos-dev proj4-dev are required by geodjango# libcrypto1.1 is required by gdal# NOTE: we actually need gdal-dev not gdal# linux-headers is required by uwsgi# gettext-dev is required by ./manage.py makemessages# TODO: optimize installation by using --virtualRUN apk update && apk upgrade \    && apk add postgresql-client \        postgresql-dev \        musl-dev \        gcc \        libxml2-dev \        libxslt-dev \        linux-headers \        gettext-dev \    && apk add --repository http://dl-cdn.alpinelinux.org/alpine/edge/main \        libcrypto1.1 \    && apk add --repository http://dl-cdn.alpinelinux.org/alpine/edge/testing \        gdal-dev \        geos-dev \        proj4-dev \    && pip install pipenvENV PYTHONUNBUFFERED=1 \    PYTHONIOENCODING=UTF-8COPY docker/backend/docker-entrypoint.sh /ENTRYPOINT ["/docker-entrypoint.sh"]WORKDIR /project/backendCOPY backend/Pipfile backend/Pipfile.lock /project/backend/RUN pipenv install --system --ignore-pipfile --dev

docker/backend/docker-entrypoint.sh

#!/bin/sh# NOTE: if there is no bash can cause# standard_init_linux.go:190: exec user process caused "no such file or directory"# https://docs.docker.com/compose/startup-order/set -euo pipefailWAIT_FOR_POSTGRES=${WAIT_FOR_POSTGRES:-true}if [[ "$WAIT_FOR_POSTGRES" = true ]]; then    DATABASE_URL=${DATABASE_URL:-postgres://postgres:postgres@postgres:5432/postgres}    # convert to connection string    # https://www.postgresql.org/docs/current/static/libpq-connect.html#LIBPQ-CONNSTRING    POSTGRES_URL=${DATABASE_URL%%\?*}    # https://www.gnu.org/software/bash/manual/bash.html#Shell-Parameter-Expansion    POSTGRES_URL=${POSTGRES_URL/#postgis:/postgres:}    # let postgres and other services (e.g. elasticsearch) to warm up...    # https://www.caktusgroup.com/blog/2017/03/14/production-ready-dockerfile-your-python-django-app/    until psql $POSTGRES_URL -c '\q'; do        >&2 echo "Postgres is not available - sleeping"        sleep 1    done    # >&2 echo "Postgres is up - executing command"fiif [[ $# -ge 1 ]]; then    exec "$@"else    echo "Applying migrations"    python manage.py migrate --noinput -v 0    echo "Generate translations"    python manage.py compilemessages --locale ru -v 0    echo "Starting server"    exec python manage.py runserver 0.0.0.0:8000fi

I solved this problem on ubuntu 18.04 by following the installation instructions for postgis detailed here: https://docs.djangoproject.com/en/2.1/ref/contrib/gis/install/postgis/

In a nutshell, run: sudo apt install postgis.

You may also need to execute commands detailed here: https://docs.djangoproject.com/en/2.1/ref/contrib/gis/install/spatialite/

I'm not fluent int docker, so translate this theory accordingly.