How to pass docker build command arguments to bash files - bash

Question

I am passing two command line arguments to my docker file like this:
docker build . -t ros-container --build-arg UBUNTU_VERSION=bionic --build-arg ROS_VERSION=melodic
I'm able to access them in my docker file, tho I couldn't get them in my bash files. I have tried both entrypoint and cmd techniques. But, non of them helped me.
Expectation
I want to access the two arguments,UBUNTU_VERSION & ROS_VERSION, from the 'script_init.bash' file. See the project structure.
Project structure
- ros_tutorials-noetic-devel
-Dockerfile
-scripts
-script_init.bash
Dockerfile
FROM ros:melodic-perception-bionic
# install packages
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update -q && \
apt-get upgrade -yq && \
apt-get install -yq wget curl git build-essential vim sudo lsb-release locales bash-
completion
# Adjust working directory
RUN locale-gen en_US.UTF-8
RUN useradd -m -d /home/ubuntu ubuntu -p `perl -e 'print crypt("ubuntu",
"salt"),"\n"'` && \
echo "ubuntu ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
# declare ros version arg
ARG ROS_VERSION
#declare ubuntu version arg
ARG UBUNTU_VERSION
# setup environment
USER ubuntu
WORKDIR /home/ubuntu
ENV UBUNTU_V=$UBUNTU_VERSION \
ROS_V=$ROS_VERSION
ENV LANG=en_US.UTF-8 LANGUAGE=en_US:en LC_ALL=en_US.UTF-8
CMD COPY ./scripts/script_init.bash /
ENTRYPOINT ["/scripts/script_init.bash /"]
script_init.bash
#!/bin/bash
set -e
export UBUNTU_CODENAME=$UBUNTU_V
export REPO_DIR=$(dirname "$SCRIPT_DIR")
export CATKIN_DIR="$HOME/catkin_ws"
export ROS_DISTRO=$ROS_V

Answer 1

You need to copy the script file into your docker image and execute it correctly.
You should be able to get it working by using this Dockerfile, note the lines at the bottom:
FROM ros:melodic-perception-bionic
# install packages
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update -q && \
apt-get upgrade -yq && \
apt-get install -yq \
bash-completion \
build-essential \
curl \
git \
locales \
lsb-release \
sudo \
vim \
wget
# Adjust working directory
RUN locale-gen en_US.UTF-8
RUN useradd -m -d /home/ubuntu ubuntu -p `perl -e 'print crypt("ubuntu", "salt"),"\n"'` && \
echo "ubuntu ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
# declare ros version arg
ARG ROS_VERSION
#declare ubuntu version arg
ARG UBUNTU_VERSION
# setup environment
USER ubuntu
WORKDIR /home/ubuntu
ENV UBUNTU_V=$UBUNTU_VERSION \
ROS_V=$ROS_VERSION
ENV LANG=en_US.UTF-8 LANGUAGE=en_US:en LC_ALL=en_US.UTF-8
# Copy your scripts directory into the docker image
COPY --chown=ubuntu:ubuntu scripts scripts
# Make sure you have execute permissions on the script
RUN chmod +x "./scripts/script_init.bash"
# Set your entrypoint to execute the script
ENTRYPOINT ["./scripts/script_init.bash"]
As a note, you could export all of these environment variables in the Dockerfile during the build without needing to execute a script at runtime, e.g. in your dockerfile:
# Export environment variables in Dockerfile
ENV UBUNTU_CODENAME=$UBUNTU_VERSION
ENV REPO_DIR=/home/ubuntu/scripts
ENV CATKIN_DIR=/home/ubuntu/catkin_ws
ENV ROS_DISTRO=$ROS_VERSION

Answer 2

I have finally found a solution that works like charm! Once you add the script folder, you can run it with bash command. In this way, you can pass what ever arguments to any bash file within the script folder.
# setup base image
FROM ros:melodic-perception-bionic
# install packages
ENV DEBIAN_FRONTEND=noninteractive
RUN apt-get update -q && \
apt-get upgrade -yq && \
apt-get install -yq wget curl git build-essential vim sudo lsb-release locales bash-completion
# Adjust working directory
RUN locale-gen en_US.UTF-8
RUN useradd -m -d /home/ubuntu ubuntu -p `perl -e 'print crypt("ubuntu", "salt"),"\n"'` && \
echo "ubuntu ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
# declare ros version arg
ARG ROS_VERSION
#declare ubuntu version arg
ARG UBUNTU_VERSION
# setup environment
USER ubuntu
WORKDIR /home/ubuntu
ENV UBUNTU_V=$UBUNTU_VERSION \
ROS_V=$ROS_VERSION
ENV LANG=en_US.UTF-8 LANGUAGE=en_US:en LC_ALL=en_US.UTF-8
# call script files
ADD /scripts /scripts
RUN bash /scripts/script_init.bash