Nishant's Machine Learning Blog

Date

Sep 11, 2022

slug

docker-cheatsheet

Status

Published

Subtitle

A comprehensive guide to Docker basics and commands

Introduction

The phrase 'But it works on my machine!!' is exactly the problem Docker solves. Docker allows us to share applications, including the operating system they were built on, along with all of the dependencies. This solves the issue of running applications across different environments.

Definitions

Image: An image is a template of our source code along with all dependencies

Container: A container is a running instance of an image. If an image is equivalent to a class, then a container is equivalent to an object of that class

Dockerfile: It is used to create the Docker Image

Docker Registry: A place where people can push their images to be accessed publicly. The most famous is DockerHub

Docker Daemon: Docker runs on a client-server architecture system. Docker Daemon is the server side of it

Commands

Start a container from an already downloaded/built image:

docker run -it <IMAGE_NAME>/<IMAGE ID>

List all running containers:

docker ps

Build an image from a Dockerfile:

docker build -t <IMAGE_NAME> .

List all images:

docker images docker images ls

How to make a DockerFile for ML projects

A Dockerfile is used to build a docker image which clones the contents of our project, sets up the base Operating systems and also downloads all the dependencies. Here are the steps to create one:

Create a file named Dockerfile and .Dockerignore file in the root of the project

Choose a base image, usually for python projects it is the Slim or the alpine Version taken from DockerHub

Set the Working directory in your image and give it a name

Copy the requirements.txt file to the working directory of the image

Install the dependencies via pip install -r requirements.txt

Copy all the project files

Docker Errors and how to solve them

If you encounter the error 'Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?', simply restart Docker Desktop. This error may occur when the connection to the docker daemon is lost after a system restart.

How to mount a docker volume

To mount the current volume to the desired location in the image, use the -v or --volume tag. For example:

Copy docker run -it -v $(pwd):/workspace/project 63b0afa6efdc bash

This mounts the current directory to /workspace/project in the Docker container. Remember that the mount is two-way: changes in the Docker image will reflect in the local filesystem and vice versa.

Removing Dangling Docker Images

Dangling images are images that aren't tagged and aren't referenced by any container. Here are the commands to remove them:

List dangling images first


docker images -f "dangling=true"

Remove all dangling images


docker rmi $(docker images -f "dangling=true" -q)

Using docker prune (recommended method)


# Remove only dangling images
docker image prune

# Remove all unused images (both dangling and unreferenced)
docker image prune -a

The docker image prune command is generally the preferred approach as it's specifically designed for this purpose and handles all the filtering for you.

If you want to confirm before deletion, these commands will prompt you before removing the images. To skip the confirmation, add the -f or --force flag:


docker image prune -f

Would you like me to explain anything else about managing Docker images?

Deleting Active Docker Containers

Here are the commands to delete active Docker containers:

To stop and remove a specific container


# Stop a specific container
docker stop <container_id_or_name>

# Remove a specific container after stopping it
docker rm <container_id_or_name>

To stop and remove all running containers


# Stop all running containers
docker stop $(docker ps -q)

# Remove all stopped containers
docker rm $(docker ps -a -q)

To force remove running containers (use with caution)


# Force remove all containers without stopping them first
docker rm -f $(docker ps -a -q)

To list containers before deleting


# List all running containers
docker ps

# List all containers (running and stopped)
docker ps -a

Would you like me to explain any of these commands in more detail?

Docker Cheatsheet