[SOLVED] Cifs mount in docker container with docker-compose

Cifs mount in docker container with docker-compose

I want to cif mount a directory into a docker-container. As there are solutions to this, I tried the --privileged flag and setting the capabilities needed:

docker-compose.yaml:

version: '2.0'
services:
  mounttest:
    image: test

    privileged: true
    cap_add:
      - SYS_ADMIN
      - DAC_READ_SEARCH
    
    restart: unless-stopped
    container_name: test
    mem_limit: 500m
    build:
      context: .
      dockerfile: Dockerfile
    volumes:
      - .:/apps/docker-test/

Dockerfile:

FROM ubuntu:18.04

ADD . /apps/docker-test/

# APT-GET
RUN apt-get update && apt-get install -y \
    sudo \
    cifs-utils

# CHMOD SHELL SCRIPTS
RUN chmod 0755 /apps/docker-test/run.sh
RUN chmod 0755 /apps/docker-test/build.sh

RUN /apps/docker-test/build.sh
CMD bash /apps/docker-test/run.sh

build.sh:

mkdir -p /test_folder
echo "Mount"
sudo mount -t cifs -o username=XXX,password=XXX,workgroup=XX //server/adress$ /test_folder

run.sh starts a python script

This does not work, instead:

docker-compose build

gives me the error:

Unable to apply new capability set

All the solutions I found only mention the privileged flag or capabilities, which are set. Can anyone help?

Solution

The answer I found, is to put the mount command into the run.sh file. As the command (or CMD) in the Dockerfile is only executed when running

docker-compose up

the mount will only be executed after the build, done beforehand, is already finished.

Therefore, before starting the python script, the mount command is executed. In my case, that only worked with the privileged flag set to true.