A Docker-Centric Approach to Software Development 🐳

In my experience developing software within a team, standardization of environment dependencies has always been a constant pain. There had been countless instances where trying to get more hands onboard resulted in more intense bouts of stress, rather than actually resolving the issue at hand.

This often comes in the form of teammates being unable to set up a project’s complex network of software dependencies which would likely conflict with their own workstation’s existing dependencies. While it is easier to manage such conflicts within python environments, the same cannot be said for C++ libraries as well as lower-level hardware-centric backends like Nvidia’s CUDA. Usually, the workarounds would be a quick dirty hack to switch different versions around while the simpler option would be to completely remove and install the required versions tediously.

Therefore, this article hopes to address this issue of environment standardization through an intuitive use of Docker.

Setup

If you do not have Docker installed, please follow the offical installation guide.
Configure docker such that you need not always have to run it with sudo. Do note this carries security risk but at least offers ease of use within the context of largely-offline development.

ℹ️ To avoid such security risk, please consider setting up Docker rootless.

Run

Downloading public docker images

docker pull <image_name:tag_name>

Building local docker images using Dockerfile

docker build -t <image_name:tag_name> .

Replace <image_name:tag_name> with something like cardboardcode/opencv:1

Run docker images as containers:

#!/usr/bin/env bash

xhost +local:docker
XSOCK=/tmp/.X11-unix
XAUTH=/tmp/.docker.xauth
xauth nlist $DISPLAY | sed -e 's/^..../ffff/' | xauth -f $XAUTH nmerge -
docker run -m 8GB -it --rm -e DISPLAY=$DISPLAY -v $XSOCK:$XSOCK -v $XAUTH:$XAUTH -e XAUTHORITY=$XAUTH -v ${PWD}:/src  -it <image_name:tag_name>
xhost -local:docker

This section covers an offline methodology of sharing varying docker images in order to achieve the quick environmental standardization among different developers:

Save a docker image as .tar file:

docker save -o <file_name>.tar <docker_image_name>
#Eg. docker save -o mynginx1.tar nginx

Load a .tar file as docker image on different workstations:

docker load < <file_name>.tar
#Eg. docker load < mynginx1.tar

Clean-Up 🧹

This section covers how to remove Docker containers/images. Create the following .bash file and run them.

1a. 🐧 [ Linux ] - `remove_all_docker_containers.bash`

#!/bin/bash

# Run the command to get container IDs in a single line
container_ids=$(docker ps -a -q)

# Check if the variable is empty
if [[ -z "$container_ids" ]]; then
  echo "No containers found."
else
  echo "Containers found:"
  # Print each container ID on a new line
  echo "$container_ids"
  # Prompt user for confirmation
  read -p "Do you want to stop and remove these containers? (y/N): " answer

  # Convert user input to lowercase
  answer=${answer,,}

  # Check if user confirms
  if [[ "$answer" == "y" || "$answer" == "yes" ]]; then
    # Use loop to stop and remove containers safely
    for container_id in $containers; do
      docker stop "$container_id" && docker rm -f "$container_id"
      echo "Removed container: $container_id"
    done
  else
    echo "Containers not stopped or removed."
  fi
fi

1b. 🪟 [ Windows - Powershell ]

docker ps -aq | Where-Object { $_ -ne "" } | ForEach-Object { docker rm $_ }

1c. 🐧 [ Linux ]

docker rm $(docker ps -aq)

2a. 🐧 [ Linux ] - `remove_all_docker_images.bash`

#!/bin/bash

# Run the command to get image IDs in a single line
image_ids=$(docker images -a -q)

# Check if the variable is empty
if [[ -z "$image_ids" ]]; then
  echo "No images found."
else
  echo "Images found:"
  # Print each image ID on a new line
  echo "$image_ids"
  # Prompt user for confirmation
  read -p "Do you want to remove all these images? (y/N): " answer

  # Convert user input to lowercase for case-insensitive comparison
  answer=${answer,,}

  # Check if user confirms (y or yes)
  if [[ "$answer" == "y" || "$answer" == "yes" ]]; then
    # Use loop to remove images safely
    for image_id in $image_ids; do
      docker rmi -f "$image_id"
      echo "Removed image: $image_id"
    done
  else
    echo "Images not removed."
  fi
fi

2b. 🪟 [ Windows - Powershell ]

docker rmi -f $(docker images -aq)

2c. 🐧 [ Linux ]

docker rmi $(docker images -q)

Limitations 👎

MEMORY - Docker images could easily exceed 10GB in memory space use.
GRAPHIC USER INTERFACE - Instantiating Graphical User Interfaces through docker instances can be problematic and impossible in many cases. While users could circumvent this, most approaches introduces security risks which one should be mindful of.
SECURITY - Please consider reading up on security risks posed in the following recent hacks:

Coinhive Cryptojacking via Malicious Docker Images (2018)

ℹ️ Coinhive has shut down as of 2019. [Ref]

“Escape the Docker” Vulnerability (2019)

ℹ️ Docker versions 18.09.2, 17.03.1-ce, and 17.06.2-ce and later addressed the issue.

HARDWARE - Hardware-specific programs that rely on devices such as GPU cannot be instantiated or virtualized effectively through Docker.

Setup

Run

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