Docker socket is not accesible in Docker.prod - django

Question

I have the following docker-compose file which builds and starts 4 containers one of them is Django container for which I am mounting the /var/run/docker.sock in volumes so that Django container can access the host docker engine.
version: '3.8'
services:
web:
build:
context: ./app
dockerfile: Dockerfile.prod
command: gunicorn hello_django.wsgi:application --bind 0.0.0.0:8000
volumes:
- static_volume:/home/app/web/staticfiles
- media_volume:/home/app/web/mediafiles
- /var/run/docker.sock:/var/run/docker.sock
expose:
- 8000
env_file:
- ./.env.prod
depends_on:
- postgresdb
restart: always
postgresdb:
container_name: postgresdb
image: timescale/timescaledb:latest-pg11
volumes:
- ./:/imports
- postgres_data:/var/lib/postgresql/data/
command: 'postgres -cshared_preload_libraries=timescaledb'
ports:
- "5432:5432"
env_file:
- ./.env.prod.db
restart: always
nginx:
build: ./nginx
volumes:
- static_volume:/home/app/web/staticfiles
- media_volume:/home/app/web/mediafiles
ports:
- 80:80
depends_on:
- web
restart: always
volttron1:
container_name: volttron1
hostname: volttron1
build:
context: ./volttron
dockerfile: Dockerfile
image: volttron/volttron:develop
volumes:
- ./volttron/platform_config.yml:/platform_config.yml
- ./volttron/configs:/home/volttron/configs
- ./volttron/volttronThingCerts:/home/volttron/volttronThingCerts
environment:
- CONFIG=/home/volttron/configs
- LOCAL_USER_ID=1000
network_mode: host
restart: always
mem_limit: 700m
cpus: 1.5
volumes:
postgres_data:
static_volume:
media_volume:
The content of the Docker.prod for django web container is following
###########
# BUILDER #
###########
# pull official base image
FROM python:3.9.6-alpine as builder
# set work directory
WORKDIR /usr/src/app
# set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1
# install psycopg2 dependencies
RUN apk update && apk add postgresql-dev gcc python3-dev musl-dev
RUN apk add libc-dev
RUN apk add --update-cache
RUN apk add --update alpine-sdk && apk add libffi-dev openssl-dev && apk --no-cache --update add build-base
# lint
RUN pip install -U pip
RUN pip install flake8==3.9.2
COPY . .
RUN flake8 --ignore=E501,F401 ./hello_django
# install dependencies
COPY ./requirements.txt .
RUN pip wheel --no-cache-dir --no-deps --wheel-dir /usr/src/app/wheels -r requirements.txt
#########
# FINAL #
#########
# pull official base image
FROM python:3.9.6-alpine
# create directory for the app user
RUN mkdir -p /home/app
# create the app user
RUN addgroup -S app && adduser -S app -G app
# create the appropriate directories
ENV HOME=/home/app
ENV APP_HOME=/home/app/web
RUN mkdir $APP_HOME
RUN mkdir $APP_HOME/staticfiles
RUN mkdir $APP_HOME/mediafiles
WORKDIR $APP_HOME
# install dependencies
RUN apk update && apk add libpq
COPY --from=builder /usr/src/app/wheels /wheels
COPY --from=builder /usr/src/app/requirements.txt .
RUN pip install --no-cache /wheels/*
# copy entrypoint.prod.sh
COPY ./entrypoint.prod.sh .
RUN sed -i 's/\r$//g' $APP_HOME/entrypoint.prod.sh
RUN chmod +x $APP_HOME/entrypoint.prod.sh
# copy project
COPY . $APP_HOME
# chown all the files to the app user
RUN chown -R app:app $APP_HOME
RUN chmod 666 /var/run/docker.sock
# change to the app user
USER app
# run entrypoint.prod.sh
ENTRYPOINT ["/home/app/web/entrypoint.prod.sh"]
The problem is in the statement RUN chmod 666 /var/run/docker.sock which raises the following error
chmod: cannot access "/var/run/docker.sock": No such file or directory
but why I am getting this error? when I have mounted the /var/run/docker.sock in docker.compose.yml file

Answer 1

You're trying to chmod the docker.sock file when building the image. The volume is only mounted and used when running the container. You'll probably need to change permissions of the socket file on the host if needed.